EcoliWiki - User contributions [en]

PMID:18028317

2009-01-16T21:19:43Z

Aashiq: /* EcoliWiki Links {{HelpIcon|Help:Literature}} */

{{RightTOC}}

 '''Kachroo, AH, Kancherla, AK, Singh, NS, Varshney, U and Mahadevan, S''' (2007) Mutations that alter the regulation of the chb operon of Escherichia coli allow utilization of cellobiose.''Mol. Microbiol.'' '''66''':1382-95

{|{{Prettytable}} align = 'center' width= '70%'
|-
|{{TableHeadingColor}} |'''Abstract''' || <protect>Wild-type strains of Escherichia coli are normally unable to metabolize cellobiose. However, cellobiose-positive (Cel(+)) mutants arise upon prolonged incubation on media containing cellobiose as the sole carbon source. We show that the Cel(+) derivatives carry two classes of mutations that act concertedly to alter the regulation of the chb operon involved in the utilization of N,N'-diacetylchitobiose. These consist of mutations that abrogate negative regulation by the repressor NagC as well as single base-pair changes in the transcriptional regulator chbR that translate into single-amino-acid substitutions. Introduction of chbR from two Cel(+) mutants resulted in activation of transcription from the chb promoter at a higher level in the presence of cellobiose, in reporter strains carrying disruptions of the chromosomal chbR and nagC. These transformants also showed a Cel(+) phenotype on MacConkey cellobiose medium, suggesting that the wild-type permease and phospho-beta-glucosidase, upon induction, could recognize, transport and cleave cellobiose respectively. This was confirmed by expressing the wild-type genes encoding the permease and phospho-beta-glucosidase under a heterologous promoter. Biochemical characterization of one of the chbR mutants, chbRN238S, showed that the mutant regulator makes stronger contact with the target DNA sequence within the chb promoter and has enhanced recognition of cellobiose 6-phosphate as an inducer compared with the wild-type regulator.</protect>
|-
|{{TableHeadingColor}} nowrap |'''Links''' || [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=18028317 PubMed] Online version:[http://dx.doi.org/10.1111/j.1365-2958.2007.05999.x 10.1111/j.1365-2958.2007.05999.x]
|}

==Significance {{HelpIcon|Help:Literature}} ==
{{LitSignificance}}
This work has clarified several misconceptions regarding the cryptic nature of the ''chb'' operon with respect to celloiose utilization(peviously known as the cryptic ''cel'' operon)(Parker and Hall, 1990). Cellobiose utilization did not require mutations that alter or modify the native specificities of the ''chb'' permease and β-glucosidase as proposed earlier (Keyhani and Roseman, 1997). Furthermore, it has implications on the evolution of novel metabolic functions from pre-exisitng genes or operons. This work is consistent with recent bioinformatic studies (Babu et al., 2006; Lozada-Chávez et al., 2006) which suggest that mutations in the transcription regulatory networks (TRNs) are primarily responsible for the variation in bacterial phenotypes.

== Useful Materials and Methods {{HelpIcon|Help:Literature}}==
{{LitMaterials}}

==Annotations {{HelpIcon|Help:Literature}}==
<protect>

{|class = 'sortable' border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"
|- {{table heading style}}
!|Gene product!!Qualifier!!GO ID!!GO term name!!Evidence Code!!with/from!!Aspect!!Notes!!Status

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=63ce1649aab8b3180235b0af7618f667.149307.T4970bfb2aa430&page=149307&pagename={{FULLPAGENAMEE}}&type=0&template=GO_table_reference edit table] || || || || || || || ||
|}
</protect>

==EcoliWiki Links {{HelpIcon|Help:Literature}} ==
{{LitLinks}}
http://ecoliwiki.net/colipedia/index.php/chbR

==References==
<ref name='PMID:15066032'/>
<ref name='PMID:9405618'/>
<ref name='PMID:2179047'/>
<ref name='PMID:16530225'/>
<ref name='PMID:16840530'/>

{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>

PMID:18028317

2009-01-16T21:18:45Z

Aashiq: /* References */

{{RightTOC}}

 '''Kachroo, AH, Kancherla, AK, Singh, NS, Varshney, U and Mahadevan, S''' (2007) Mutations that alter the regulation of the chb operon of Escherichia coli allow utilization of cellobiose.''Mol. Microbiol.'' '''66''':1382-95

{|{{Prettytable}} align = 'center' width= '70%'
|-
|{{TableHeadingColor}} |'''Abstract''' || <protect>Wild-type strains of Escherichia coli are normally unable to metabolize cellobiose. However, cellobiose-positive (Cel(+)) mutants arise upon prolonged incubation on media containing cellobiose as the sole carbon source. We show that the Cel(+) derivatives carry two classes of mutations that act concertedly to alter the regulation of the chb operon involved in the utilization of N,N'-diacetylchitobiose. These consist of mutations that abrogate negative regulation by the repressor NagC as well as single base-pair changes in the transcriptional regulator chbR that translate into single-amino-acid substitutions. Introduction of chbR from two Cel(+) mutants resulted in activation of transcription from the chb promoter at a higher level in the presence of cellobiose, in reporter strains carrying disruptions of the chromosomal chbR and nagC. These transformants also showed a Cel(+) phenotype on MacConkey cellobiose medium, suggesting that the wild-type permease and phospho-beta-glucosidase, upon induction, could recognize, transport and cleave cellobiose respectively. This was confirmed by expressing the wild-type genes encoding the permease and phospho-beta-glucosidase under a heterologous promoter. Biochemical characterization of one of the chbR mutants, chbRN238S, showed that the mutant regulator makes stronger contact with the target DNA sequence within the chb promoter and has enhanced recognition of cellobiose 6-phosphate as an inducer compared with the wild-type regulator.</protect>
|-
|{{TableHeadingColor}} nowrap |'''Links''' || [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=18028317 PubMed] Online version:[http://dx.doi.org/10.1111/j.1365-2958.2007.05999.x 10.1111/j.1365-2958.2007.05999.x]
|}

==Significance {{HelpIcon|Help:Literature}} ==
{{LitSignificance}}
This work has clarified several misconceptions regarding the cryptic nature of the ''chb'' operon with respect to celloiose utilization(peviously known as the cryptic ''cel'' operon)(Parker and Hall, 1990). Cellobiose utilization did not require mutations that alter or modify the native specificities of the ''chb'' permease and β-glucosidase as proposed earlier (Keyhani and Roseman, 1997). Furthermore, it has implications on the evolution of novel metabolic functions from pre-exisitng genes or operons. This work is consistent with recent bioinformatic studies (Babu et al., 2006; Lozada-Chávez et al., 2006) which suggest that mutations in the transcription regulatory networks (TRNs) are primarily responsible for the variation in bacterial phenotypes.

== Useful Materials and Methods {{HelpIcon|Help:Literature}}==
{{LitMaterials}}

==Annotations {{HelpIcon|Help:Literature}}==
<protect>

{|class = 'sortable' border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"
|- {{table heading style}}
!|Gene product!!Qualifier!!GO ID!!GO term name!!Evidence Code!!with/from!!Aspect!!Notes!!Status

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=63ce1649aab8b3180235b0af7618f667.149307.T4970bfb2aa430&page=149307&pagename={{FULLPAGENAMEE}}&type=0&template=GO_table_reference edit table] || || || || || || || ||
|}
</protect>

==EcoliWiki Links {{HelpIcon|Help:Literature}} ==
{{LitLinks}}

==References==
<ref name='PMID:15066032'/>
<ref name='PMID:9405618'/>
<ref name='PMID:2179047'/>
<ref name='PMID:16530225'/>
<ref name='PMID:16840530'/>

{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>

PMID:18028317

2009-01-16T21:12:47Z

Aashiq: /* References */

{{RightTOC}}

 '''Kachroo, AH, Kancherla, AK, Singh, NS, Varshney, U and Mahadevan, S''' (2007) Mutations that alter the regulation of the chb operon of Escherichia coli allow utilization of cellobiose.''Mol. Microbiol.'' '''66''':1382-95

{|{{Prettytable}} align = 'center' width= '70%'
|-
|{{TableHeadingColor}} |'''Abstract''' || <protect>Wild-type strains of Escherichia coli are normally unable to metabolize cellobiose. However, cellobiose-positive (Cel(+)) mutants arise upon prolonged incubation on media containing cellobiose as the sole carbon source. We show that the Cel(+) derivatives carry two classes of mutations that act concertedly to alter the regulation of the chb operon involved in the utilization of N,N'-diacetylchitobiose. These consist of mutations that abrogate negative regulation by the repressor NagC as well as single base-pair changes in the transcriptional regulator chbR that translate into single-amino-acid substitutions. Introduction of chbR from two Cel(+) mutants resulted in activation of transcription from the chb promoter at a higher level in the presence of cellobiose, in reporter strains carrying disruptions of the chromosomal chbR and nagC. These transformants also showed a Cel(+) phenotype on MacConkey cellobiose medium, suggesting that the wild-type permease and phospho-beta-glucosidase, upon induction, could recognize, transport and cleave cellobiose respectively. This was confirmed by expressing the wild-type genes encoding the permease and phospho-beta-glucosidase under a heterologous promoter. Biochemical characterization of one of the chbR mutants, chbRN238S, showed that the mutant regulator makes stronger contact with the target DNA sequence within the chb promoter and has enhanced recognition of cellobiose 6-phosphate as an inducer compared with the wild-type regulator.</protect>
|-
|{{TableHeadingColor}} nowrap |'''Links''' || [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=18028317 PubMed] Online version:[http://dx.doi.org/10.1111/j.1365-2958.2007.05999.x 10.1111/j.1365-2958.2007.05999.x]
|}

==Significance {{HelpIcon|Help:Literature}} ==
{{LitSignificance}}
This work has clarified several misconceptions regarding the cryptic nature of the ''chb'' operon with respect to celloiose utilization(peviously known as the cryptic ''cel'' operon)(Parker and Hall, 1990). Cellobiose utilization did not require mutations that alter or modify the native specificities of the ''chb'' permease and β-glucosidase as proposed earlier (Keyhani and Roseman, 1997). Furthermore, it has implications on the evolution of novel metabolic functions from pre-exisitng genes or operons. This work is consistent with recent bioinformatic studies (Babu et al., 2006; Lozada-Chávez et al., 2006) which suggest that mutations in the transcription regulatory networks (TRNs) are primarily responsible for the variation in bacterial phenotypes.

== Useful Materials and Methods {{HelpIcon|Help:Literature}}==
{{LitMaterials}}

==Annotations {{HelpIcon|Help:Literature}}==
<protect>

{|class = 'sortable' border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"
|- {{table heading style}}
!|Gene product!!Qualifier!!GO ID!!GO term name!!Evidence Code!!with/from!!Aspect!!Notes!!Status

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=63ce1649aab8b3180235b0af7618f667.149307.T4970bfb2aa430&page=149307&pagename={{FULLPAGENAMEE}}&type=0&template=GO_table_reference edit table] || || || || || || || ||
|}
</protect>

==EcoliWiki Links {{HelpIcon|Help:Literature}} ==
{{LitLinks}}

==References==
<ref name='PMID:15066032'/>
<ref name='PMID:9405618'/>
<ref name='PMID:2179047'/>

{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>

PMID:18028317

2009-01-16T21:11:15Z

Aashiq: /* References */

{{RightTOC}}

 '''Kachroo, AH, Kancherla, AK, Singh, NS, Varshney, U and Mahadevan, S''' (2007) Mutations that alter the regulation of the chb operon of Escherichia coli allow utilization of cellobiose.''Mol. Microbiol.'' '''66''':1382-95

{|{{Prettytable}} align = 'center' width= '70%'
|-
|{{TableHeadingColor}} |'''Abstract''' || <protect>Wild-type strains of Escherichia coli are normally unable to metabolize cellobiose. However, cellobiose-positive (Cel(+)) mutants arise upon prolonged incubation on media containing cellobiose as the sole carbon source. We show that the Cel(+) derivatives carry two classes of mutations that act concertedly to alter the regulation of the chb operon involved in the utilization of N,N'-diacetylchitobiose. These consist of mutations that abrogate negative regulation by the repressor NagC as well as single base-pair changes in the transcriptional regulator chbR that translate into single-amino-acid substitutions. Introduction of chbR from two Cel(+) mutants resulted in activation of transcription from the chb promoter at a higher level in the presence of cellobiose, in reporter strains carrying disruptions of the chromosomal chbR and nagC. These transformants also showed a Cel(+) phenotype on MacConkey cellobiose medium, suggesting that the wild-type permease and phospho-beta-glucosidase, upon induction, could recognize, transport and cleave cellobiose respectively. This was confirmed by expressing the wild-type genes encoding the permease and phospho-beta-glucosidase under a heterologous promoter. Biochemical characterization of one of the chbR mutants, chbRN238S, showed that the mutant regulator makes stronger contact with the target DNA sequence within the chb promoter and has enhanced recognition of cellobiose 6-phosphate as an inducer compared with the wild-type regulator.</protect>
|-
|{{TableHeadingColor}} nowrap |'''Links''' || [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=18028317 PubMed] Online version:[http://dx.doi.org/10.1111/j.1365-2958.2007.05999.x 10.1111/j.1365-2958.2007.05999.x]
|}

==Significance {{HelpIcon|Help:Literature}} ==
{{LitSignificance}}
This work has clarified several misconceptions regarding the cryptic nature of the ''chb'' operon with respect to celloiose utilization(peviously known as the cryptic ''cel'' operon)(Parker and Hall, 1990). Cellobiose utilization did not require mutations that alter or modify the native specificities of the ''chb'' permease and β-glucosidase as proposed earlier (Keyhani and Roseman, 1997). Furthermore, it has implications on the evolution of novel metabolic functions from pre-exisitng genes or operons. This work is consistent with recent bioinformatic studies (Babu et al., 2006; Lozada-Chávez et al., 2006) which suggest that mutations in the transcription regulatory networks (TRNs) are primarily responsible for the variation in bacterial phenotypes.

== Useful Materials and Methods {{HelpIcon|Help:Literature}}==
{{LitMaterials}}

==Annotations {{HelpIcon|Help:Literature}}==
<protect>

{|class = 'sortable' border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"
|- {{table heading style}}
!|Gene product!!Qualifier!!GO ID!!GO term name!!Evidence Code!!with/from!!Aspect!!Notes!!Status

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=63ce1649aab8b3180235b0af7618f667.149307.T4970bfb2aa430&page=149307&pagename={{FULLPAGENAMEE}}&type=0&template=GO_table_reference edit table] || || || || || || || ||
|}
</protect>

==EcoliWiki Links {{HelpIcon|Help:Literature}} ==
{{LitLinks}}

==References==
<ref name='PMID:15066032'/>
<ref name='PMID:9405618'/>

{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>

PMID:18028317

2009-01-16T21:08:59Z

Aashiq: /* References */

{{RightTOC}}

 '''Kachroo, AH, Kancherla, AK, Singh, NS, Varshney, U and Mahadevan, S''' (2007) Mutations that alter the regulation of the chb operon of Escherichia coli allow utilization of cellobiose.''Mol. Microbiol.'' '''66''':1382-95

{|{{Prettytable}} align = 'center' width= '70%'
|-
|{{TableHeadingColor}} |'''Abstract''' || <protect>Wild-type strains of Escherichia coli are normally unable to metabolize cellobiose. However, cellobiose-positive (Cel(+)) mutants arise upon prolonged incubation on media containing cellobiose as the sole carbon source. We show that the Cel(+) derivatives carry two classes of mutations that act concertedly to alter the regulation of the chb operon involved in the utilization of N,N'-diacetylchitobiose. These consist of mutations that abrogate negative regulation by the repressor NagC as well as single base-pair changes in the transcriptional regulator chbR that translate into single-amino-acid substitutions. Introduction of chbR from two Cel(+) mutants resulted in activation of transcription from the chb promoter at a higher level in the presence of cellobiose, in reporter strains carrying disruptions of the chromosomal chbR and nagC. These transformants also showed a Cel(+) phenotype on MacConkey cellobiose medium, suggesting that the wild-type permease and phospho-beta-glucosidase, upon induction, could recognize, transport and cleave cellobiose respectively. This was confirmed by expressing the wild-type genes encoding the permease and phospho-beta-glucosidase under a heterologous promoter. Biochemical characterization of one of the chbR mutants, chbRN238S, showed that the mutant regulator makes stronger contact with the target DNA sequence within the chb promoter and has enhanced recognition of cellobiose 6-phosphate as an inducer compared with the wild-type regulator.</protect>
|-
|{{TableHeadingColor}} nowrap |'''Links''' || [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=18028317 PubMed] Online version:[http://dx.doi.org/10.1111/j.1365-2958.2007.05999.x 10.1111/j.1365-2958.2007.05999.x]
|}

==Significance {{HelpIcon|Help:Literature}} ==
{{LitSignificance}}
This work has clarified several misconceptions regarding the cryptic nature of the ''chb'' operon with respect to celloiose utilization(peviously known as the cryptic ''cel'' operon)(Parker and Hall, 1990). Cellobiose utilization did not require mutations that alter or modify the native specificities of the ''chb'' permease and β-glucosidase as proposed earlier (Keyhani and Roseman, 1997). Furthermore, it has implications on the evolution of novel metabolic functions from pre-exisitng genes or operons. This work is consistent with recent bioinformatic studies (Babu et al., 2006; Lozada-Chávez et al., 2006) which suggest that mutations in the transcription regulatory networks (TRNs) are primarily responsible for the variation in bacterial phenotypes.

== Useful Materials and Methods {{HelpIcon|Help:Literature}}==
{{LitMaterials}}

==Annotations {{HelpIcon|Help:Literature}}==
<protect>

{|class = 'sortable' border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"
|- {{table heading style}}
!|Gene product!!Qualifier!!GO ID!!GO term name!!Evidence Code!!with/from!!Aspect!!Notes!!Status

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=63ce1649aab8b3180235b0af7618f667.149307.T4970bfb2aa430&page=149307&pagename={{FULLPAGENAMEE}}&type=0&template=GO_table_reference edit table] || || || || || || || ||
|}
</protect>

==EcoliWiki Links {{HelpIcon|Help:Literature}} ==
{{LitLinks}}

==References==
<ref name='PMID:15066032'/>
<ref name='PMID:9405618'/>

PMID:18028317

2009-01-16T21:08:14Z

Aashiq: /* References */

PMID:18028317

2009-01-16T21:07:19Z

Aashiq: /* See also */

PMID:18028317

2009-01-16T21:06:41Z

Aashiq: /* References */

PMID:18028317

2009-01-16T21:06:22Z

Aashiq: /* References */

{{RightTOC}}

 '''Kachroo, AH, Kancherla, AK, Singh, NS, Varshney, U and Mahadevan, S''' (2007) Mutations that alter the regulation of the chb operon of Escherichia coli allow utilization of cellobiose.''Mol. Microbiol.'' '''66''':1382-95

{|{{Prettytable}} align = 'center' width= '70%'
|-
|{{TableHeadingColor}} |'''Abstract''' || <protect>Wild-type strains of Escherichia coli are normally unable to metabolize cellobiose. However, cellobiose-positive (Cel(+)) mutants arise upon prolonged incubation on media containing cellobiose as the sole carbon source. We show that the Cel(+) derivatives carry two classes of mutations that act concertedly to alter the regulation of the chb operon involved in the utilization of N,N'-diacetylchitobiose. These consist of mutations that abrogate negative regulation by the repressor NagC as well as single base-pair changes in the transcriptional regulator chbR that translate into single-amino-acid substitutions. Introduction of chbR from two Cel(+) mutants resulted in activation of transcription from the chb promoter at a higher level in the presence of cellobiose, in reporter strains carrying disruptions of the chromosomal chbR and nagC. These transformants also showed a Cel(+) phenotype on MacConkey cellobiose medium, suggesting that the wild-type permease and phospho-beta-glucosidase, upon induction, could recognize, transport and cleave cellobiose respectively. This was confirmed by expressing the wild-type genes encoding the permease and phospho-beta-glucosidase under a heterologous promoter. Biochemical characterization of one of the chbR mutants, chbRN238S, showed that the mutant regulator makes stronger contact with the target DNA sequence within the chb promoter and has enhanced recognition of cellobiose 6-phosphate as an inducer compared with the wild-type regulator.</protect>
|-
|{{TableHeadingColor}} nowrap |'''Links''' || [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=18028317 PubMed] Online version:[http://dx.doi.org/10.1111/j.1365-2958.2007.05999.x 10.1111/j.1365-2958.2007.05999.x]
|}

==Significance {{HelpIcon|Help:Literature}} ==
{{LitSignificance}}
This work has clarified several misconceptions regarding the cryptic nature of the ''chb'' operon with respect to celloiose utilization(peviously known as the cryptic ''cel'' operon)(Parker and Hall, 1990). Cellobiose utilization did not require mutations that alter or modify the native specificities of the ''chb'' permease and β-glucosidase as proposed earlier (Keyhani and Roseman, 1997). Furthermore, it has implications on the evolution of novel metabolic functions from pre-exisitng genes or operons. This work is consistent with recent bioinformatic studies (Babu et al., 2006; Lozada-Chávez et al., 2006) which suggest that mutations in the transcription regulatory networks (TRNs) are primarily responsible for the variation in bacterial phenotypes.

== Useful Materials and Methods {{HelpIcon|Help:Literature}}==
{{LitMaterials}}

==Annotations {{HelpIcon|Help:Literature}}==
<protect>

{|class = 'sortable' border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"
|- {{table heading style}}
!|Gene product!!Qualifier!!GO ID!!GO term name!!Evidence Code!!with/from!!Aspect!!Notes!!Status

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=63ce1649aab8b3180235b0af7618f667.149307.T4970bfb2aa430&page=149307&pagename={{FULLPAGENAMEE}}&type=0&template=GO_table_reference edit table] || || || || || || || ||
|}
</protect>

==EcoliWiki Links {{HelpIcon|Help:Literature}} ==
{{LitLinks}}

==See also==

==References==
{{RefHelp}}
<references/>
<ref name='PMID:15066032'/>

PMID:18028317

2009-01-16T21:05:48Z

Aashiq: /* References */

{{RightTOC}}

 '''Kachroo, AH, Kancherla, AK, Singh, NS, Varshney, U and Mahadevan, S''' (2007) Mutations that alter the regulation of the chb operon of Escherichia coli allow utilization of cellobiose.''Mol. Microbiol.'' '''66''':1382-95

{|{{Prettytable}} align = 'center' width= '70%'
|-
|{{TableHeadingColor}} |'''Abstract''' || <protect>Wild-type strains of Escherichia coli are normally unable to metabolize cellobiose. However, cellobiose-positive (Cel(+)) mutants arise upon prolonged incubation on media containing cellobiose as the sole carbon source. We show that the Cel(+) derivatives carry two classes of mutations that act concertedly to alter the regulation of the chb operon involved in the utilization of N,N'-diacetylchitobiose. These consist of mutations that abrogate negative regulation by the repressor NagC as well as single base-pair changes in the transcriptional regulator chbR that translate into single-amino-acid substitutions. Introduction of chbR from two Cel(+) mutants resulted in activation of transcription from the chb promoter at a higher level in the presence of cellobiose, in reporter strains carrying disruptions of the chromosomal chbR and nagC. These transformants also showed a Cel(+) phenotype on MacConkey cellobiose medium, suggesting that the wild-type permease and phospho-beta-glucosidase, upon induction, could recognize, transport and cleave cellobiose respectively. This was confirmed by expressing the wild-type genes encoding the permease and phospho-beta-glucosidase under a heterologous promoter. Biochemical characterization of one of the chbR mutants, chbRN238S, showed that the mutant regulator makes stronger contact with the target DNA sequence within the chb promoter and has enhanced recognition of cellobiose 6-phosphate as an inducer compared with the wild-type regulator.</protect>
|-
|{{TableHeadingColor}} nowrap |'''Links''' || [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=18028317 PubMed] Online version:[http://dx.doi.org/10.1111/j.1365-2958.2007.05999.x 10.1111/j.1365-2958.2007.05999.x]
|}

==Significance {{HelpIcon|Help:Literature}} ==
{{LitSignificance}}
This work has clarified several misconceptions regarding the cryptic nature of the ''chb'' operon with respect to celloiose utilization(peviously known as the cryptic ''cel'' operon)(Parker and Hall, 1990). Cellobiose utilization did not require mutations that alter or modify the native specificities of the ''chb'' permease and β-glucosidase as proposed earlier (Keyhani and Roseman, 1997). Furthermore, it has implications on the evolution of novel metabolic functions from pre-exisitng genes or operons. This work is consistent with recent bioinformatic studies (Babu et al., 2006; Lozada-Chávez et al., 2006) which suggest that mutations in the transcription regulatory networks (TRNs) are primarily responsible for the variation in bacterial phenotypes.

== Useful Materials and Methods {{HelpIcon|Help:Literature}}==
{{LitMaterials}}

==Annotations {{HelpIcon|Help:Literature}}==
<protect>

{|class = 'sortable' border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"
|- {{table heading style}}
!|Gene product!!Qualifier!!GO ID!!GO term name!!Evidence Code!!with/from!!Aspect!!Notes!!Status

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=63ce1649aab8b3180235b0af7618f667.149307.T4970bfb2aa430&page=149307&pagename={{FULLPAGENAMEE}}&type=0&template=GO_table_reference edit table] || || || || || || || ||
|}
</protect>

==EcoliWiki Links {{HelpIcon|Help:Literature}} ==
{{LitLinks}}

==See also==

==References==
{{RefHelp}}
<references/>
<ref name='PMID:18028317'/>

PMID:18028317

2009-01-16T21:03:49Z

Aashiq: /* Significance {{HelpIcon|Help:Literature}} */

{{RightTOC}}

 '''Kachroo, AH, Kancherla, AK, Singh, NS, Varshney, U and Mahadevan, S''' (2007) Mutations that alter the regulation of the chb operon of Escherichia coli allow utilization of cellobiose.''Mol. Microbiol.'' '''66''':1382-95

{|{{Prettytable}} align = 'center' width= '70%'
|-
|{{TableHeadingColor}} |'''Abstract''' || <protect>Wild-type strains of Escherichia coli are normally unable to metabolize cellobiose. However, cellobiose-positive (Cel(+)) mutants arise upon prolonged incubation on media containing cellobiose as the sole carbon source. We show that the Cel(+) derivatives carry two classes of mutations that act concertedly to alter the regulation of the chb operon involved in the utilization of N,N'-diacetylchitobiose. These consist of mutations that abrogate negative regulation by the repressor NagC as well as single base-pair changes in the transcriptional regulator chbR that translate into single-amino-acid substitutions. Introduction of chbR from two Cel(+) mutants resulted in activation of transcription from the chb promoter at a higher level in the presence of cellobiose, in reporter strains carrying disruptions of the chromosomal chbR and nagC. These transformants also showed a Cel(+) phenotype on MacConkey cellobiose medium, suggesting that the wild-type permease and phospho-beta-glucosidase, upon induction, could recognize, transport and cleave cellobiose respectively. This was confirmed by expressing the wild-type genes encoding the permease and phospho-beta-glucosidase under a heterologous promoter. Biochemical characterization of one of the chbR mutants, chbRN238S, showed that the mutant regulator makes stronger contact with the target DNA sequence within the chb promoter and has enhanced recognition of cellobiose 6-phosphate as an inducer compared with the wild-type regulator.</protect>
|-
|{{TableHeadingColor}} nowrap |'''Links''' || [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=18028317 PubMed] Online version:[http://dx.doi.org/10.1111/j.1365-2958.2007.05999.x 10.1111/j.1365-2958.2007.05999.x]
|}

==Significance {{HelpIcon|Help:Literature}} ==
{{LitSignificance}}
This work has clarified several misconceptions regarding the cryptic nature of the ''chb'' operon with respect to celloiose utilization(peviously known as the cryptic ''cel'' operon)(Parker and Hall, 1990). Cellobiose utilization did not require mutations that alter or modify the native specificities of the ''chb'' permease and β-glucosidase as proposed earlier (Keyhani and Roseman, 1997). Furthermore, it has implications on the evolution of novel metabolic functions from pre-exisitng genes or operons. This work is consistent with recent bioinformatic studies (Babu et al., 2006; Lozada-Chávez et al., 2006) which suggest that mutations in the transcription regulatory networks (TRNs) are primarily responsible for the variation in bacterial phenotypes.

== Useful Materials and Methods {{HelpIcon|Help:Literature}}==
{{LitMaterials}}

==Annotations {{HelpIcon|Help:Literature}}==
<protect>

{|class = 'sortable' border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"
|- {{table heading style}}
!|Gene product!!Qualifier!!GO ID!!GO term name!!Evidence Code!!with/from!!Aspect!!Notes!!Status

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=63ce1649aab8b3180235b0af7618f667.149307.T4970bfb2aa430&page=149307&pagename={{FULLPAGENAMEE}}&type=0&template=GO_table_reference edit table] || || || || || || || ||
|}
</protect>

==EcoliWiki Links {{HelpIcon|Help:Literature}} ==
{{LitLinks}}

==See also==

==References==
{{RefHelp}}
<references/>

chbR:Quickview

2009-01-16T18:11:52Z

Aashiq: /* References */

{{#css:Suppresslinks.css}}<css>{{:Suppresslinks.css}}</css>
<noinclude>{{TabsTop}}
{{Tab On|Quickview|chbR}}{{Tab|Gene|chbR}}{{Tab|Gene Product(s)|chbR}}{{Tab|Expression|chbR}}{{Tab|Evolution|chbR}}{{Tab|On One Page|chbR}}{{TabsBottom}}
{|
|- style="background-color:white; border:solid 2px #CCFFFF; text-align:center; white-space: nowrap;"
|{{Sub}}[[#References| References]]
|{{Sub}}[[Talk:{{PAGENAMEE}}| Suggestions]]
|}
</noinclude>


{|border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"

|-
!align=left {{table_heading_style}} |Gene Name
||
[[chbR:Gene|''chbR]]'' (synonyms: ''ECK1733, b1735, JW1724, celD'')<ref name='LIB:Riley_2006'/>
|-
!align=left {{table_heading_style}} |Product(s)
||
[[chbR:Gene_Product(s)|ChbR product]]<ref name='LIB:Riley_2006'/>: DNA-binding transcriptional dual regulator product, B1735 product, CelD product
|-
!align=left {{table_heading_style}} |Description
||
ChbR transcriptional regulator<ref name='LIB:EcoCyc10.6'/> ChbR transcriptional dual regulator<ref name='LIB:EcoCyc11.1'/>

|-
!align=left {{table_heading_style}} |Knock-Out Phenotype
||
Chitobiose negative and Cellobiose negative
|-
!align=left {{table_heading_style}} |Regulation/Expression
||
transcription unit(s): [[:Category:Txn_unit:chbBCARFG|chbBCARFG]]<ref name='LIB:EcoCyc10.6'/>
|-
!align=left {{table_heading_style}} |Regulation/Activity
||
Repressor in the absence of inducer and activator in the presence of inducer.

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=421aa90e079fa326b6494f812ad13e79.5227.V46a99e92bc3a0&page=5227&pagename={{FULLPAGENAMEE}}&type=1&template=Quickview_table edit table] ||
|}

{{Quickview_table_help}}
<protect></protect>
===Notes===
{{BacktoTop}}

<noinclude>
ChbR was initially reported as a repressor of the ''chb'' operon. However later work showed that this protein is an activator as well as the repressor of the ''chb'' operon. The mutations in the ''chbR'' have also been reported to confer Cel+ phenotype to ''E. coli''.

==References==
<ref name='PMID:18028317'/>
<ref name='PMID:15066032'/>
<ref name='PMID:9405618'/>

{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>

chbR:Quickview

2009-01-16T18:10:54Z

Aashiq: /* References */

{{#css:Suppresslinks.css}}<css>{{:Suppresslinks.css}}</css>
<noinclude>{{TabsTop}}
{{Tab On|Quickview|chbR}}{{Tab|Gene|chbR}}{{Tab|Gene Product(s)|chbR}}{{Tab|Expression|chbR}}{{Tab|Evolution|chbR}}{{Tab|On One Page|chbR}}{{TabsBottom}}
{|
|- style="background-color:white; border:solid 2px #CCFFFF; text-align:center; white-space: nowrap;"
|{{Sub}}[[#References| References]]
|{{Sub}}[[Talk:{{PAGENAMEE}}| Suggestions]]
|}
</noinclude>


{|border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"

|-
!align=left {{table_heading_style}} |Gene Name
||
[[chbR:Gene|''chbR]]'' (synonyms: ''ECK1733, b1735, JW1724, celD'')<ref name='LIB:Riley_2006'/>
|-
!align=left {{table_heading_style}} |Product(s)
||
[[chbR:Gene_Product(s)|ChbR product]]<ref name='LIB:Riley_2006'/>: DNA-binding transcriptional dual regulator product, B1735 product, CelD product
|-
!align=left {{table_heading_style}} |Description
||
ChbR transcriptional regulator<ref name='LIB:EcoCyc10.6'/> ChbR transcriptional dual regulator<ref name='LIB:EcoCyc11.1'/>

|-
!align=left {{table_heading_style}} |Knock-Out Phenotype
||
Chitobiose negative and Cellobiose negative
|-
!align=left {{table_heading_style}} |Regulation/Expression
||
transcription unit(s): [[:Category:Txn_unit:chbBCARFG|chbBCARFG]]<ref name='LIB:EcoCyc10.6'/>
|-
!align=left {{table_heading_style}} |Regulation/Activity
||
Repressor in the absence of inducer and activator in the presence of inducer.

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=421aa90e079fa326b6494f812ad13e79.5227.V46a99e92bc3a0&page=5227&pagename={{FULLPAGENAMEE}}&type=1&template=Quickview_table edit table] ||
|}

{{Quickview_table_help}}
<protect></protect>
===Notes===
{{BacktoTop}}

<noinclude>
ChbR was initially reported as a repressor of the ''chb'' operon. However later work showed that this protein is an activator as well as the repressor of the ''chb'' operon. The mutations in the ''chbR'' have also been reported to confer Cel+ phenotype to ''E. coli''.

==References==
<ref name='PMID:18028317'/>
<ref name='PMID:15066032'/>

{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>

chbR:Quickview

2009-01-16T18:09:26Z

Aashiq: /* References */

{{#css:Suppresslinks.css}}<css>{{:Suppresslinks.css}}</css>
<noinclude>{{TabsTop}}
{{Tab On|Quickview|chbR}}{{Tab|Gene|chbR}}{{Tab|Gene Product(s)|chbR}}{{Tab|Expression|chbR}}{{Tab|Evolution|chbR}}{{Tab|On One Page|chbR}}{{TabsBottom}}
{|
|- style="background-color:white; border:solid 2px #CCFFFF; text-align:center; white-space: nowrap;"
|{{Sub}}[[#References| References]]
|{{Sub}}[[Talk:{{PAGENAMEE}}| Suggestions]]
|}
</noinclude>


{|border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"

|-
!align=left {{table_heading_style}} |Gene Name
||
[[chbR:Gene|''chbR]]'' (synonyms: ''ECK1733, b1735, JW1724, celD'')<ref name='LIB:Riley_2006'/>
|-
!align=left {{table_heading_style}} |Product(s)
||
[[chbR:Gene_Product(s)|ChbR product]]<ref name='LIB:Riley_2006'/>: DNA-binding transcriptional dual regulator product, B1735 product, CelD product
|-
!align=left {{table_heading_style}} |Description
||
ChbR transcriptional regulator<ref name='LIB:EcoCyc10.6'/> ChbR transcriptional dual regulator<ref name='LIB:EcoCyc11.1'/>

|-
!align=left {{table_heading_style}} |Knock-Out Phenotype
||
Chitobiose negative and Cellobiose negative
|-
!align=left {{table_heading_style}} |Regulation/Expression
||
transcription unit(s): [[:Category:Txn_unit:chbBCARFG|chbBCARFG]]<ref name='LIB:EcoCyc10.6'/>
|-
!align=left {{table_heading_style}} |Regulation/Activity
||
Repressor in the absence of inducer and activator in the presence of inducer.

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=421aa90e079fa326b6494f812ad13e79.5227.V46a99e92bc3a0&page=5227&pagename={{FULLPAGENAMEE}}&type=1&template=Quickview_table edit table] ||
|}

{{Quickview_table_help}}
<protect></protect>
===Notes===
{{BacktoTop}}

<noinclude>
ChbR was initially reported as a repressor of the ''chb'' operon. However later work showed that this protein is an activator as well as the repressor of the ''chb'' operon. The mutations in the ''chbR'' have also been reported to confer Cel+ phenotype to ''E. coli''.

==References==
<ref name='PMID:18028317'/>
{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>

chbR:Quickview

2009-01-16T18:08:46Z

Aashiq: /* References */

{{#css:Suppresslinks.css}}<css>{{:Suppresslinks.css}}</css>
<noinclude>{{TabsTop}}
{{Tab On|Quickview|chbR}}{{Tab|Gene|chbR}}{{Tab|Gene Product(s)|chbR}}{{Tab|Expression|chbR}}{{Tab|Evolution|chbR}}{{Tab|On One Page|chbR}}{{TabsBottom}}
{|
|- style="background-color:white; border:solid 2px #CCFFFF; text-align:center; white-space: nowrap;"
|{{Sub}}[[#References| References]]
|{{Sub}}[[Talk:{{PAGENAMEE}}| Suggestions]]
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{|border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"

|-
!align=left {{table_heading_style}} |Gene Name
||
[[chbR:Gene|''chbR]]'' (synonyms: ''ECK1733, b1735, JW1724, celD'')<ref name='LIB:Riley_2006'/>
|-
!align=left {{table_heading_style}} |Product(s)
||
[[chbR:Gene_Product(s)|ChbR product]]<ref name='LIB:Riley_2006'/>: DNA-binding transcriptional dual regulator product, B1735 product, CelD product
|-
!align=left {{table_heading_style}} |Description
||
ChbR transcriptional regulator<ref name='LIB:EcoCyc10.6'/> ChbR transcriptional dual regulator<ref name='LIB:EcoCyc11.1'/>

|-
!align=left {{table_heading_style}} |Knock-Out Phenotype
||
Chitobiose negative and Cellobiose negative
|-
!align=left {{table_heading_style}} |Regulation/Expression
||
transcription unit(s): [[:Category:Txn_unit:chbBCARFG|chbBCARFG]]<ref name='LIB:EcoCyc10.6'/>
|-
!align=left {{table_heading_style}} |Regulation/Activity
||
Repressor in the absence of inducer and activator in the presence of inducer.

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=421aa90e079fa326b6494f812ad13e79.5227.V46a99e92bc3a0&page=5227&pagename={{FULLPAGENAMEE}}&type=1&template=Quickview_table edit table] ||
|}

{{Quickview_table_help}}
<protect></protect>
===Notes===
{{BacktoTop}}

<noinclude>
ChbR was initially reported as a repressor of the ''chb'' operon. However later work showed that this protein is an activator as well as the repressor of the ''chb'' operon. The mutations in the ''chbR'' have also been reported to confer Cel+ phenotype to ''E. coli''.

==References==
{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>

<ref name='PMID:18028317'/>

chbR:Quickview

2009-01-16T18:02:59Z

Aashiq: /* Notes */

{{#css:Suppresslinks.css}}<css>{{:Suppresslinks.css}}</css>
<noinclude>{{TabsTop}}
{{Tab On|Quickview|chbR}}{{Tab|Gene|chbR}}{{Tab|Gene Product(s)|chbR}}{{Tab|Expression|chbR}}{{Tab|Evolution|chbR}}{{Tab|On One Page|chbR}}{{TabsBottom}}
{|
|- style="background-color:white; border:solid 2px #CCFFFF; text-align:center; white-space: nowrap;"
|{{Sub}}[[#References| References]]
|{{Sub}}[[Talk:{{PAGENAMEE}}| Suggestions]]
|}
</noinclude>


{|border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"

|-
!align=left {{table_heading_style}} |Gene Name
||
[[chbR:Gene|''chbR]]'' (synonyms: ''ECK1733, b1735, JW1724, celD'')<ref name='LIB:Riley_2006'/>
|-
!align=left {{table_heading_style}} |Product(s)
||
[[chbR:Gene_Product(s)|ChbR product]]<ref name='LIB:Riley_2006'/>: DNA-binding transcriptional dual regulator product, B1735 product, CelD product
|-
!align=left {{table_heading_style}} |Description
||
ChbR transcriptional regulator<ref name='LIB:EcoCyc10.6'/> ChbR transcriptional dual regulator<ref name='LIB:EcoCyc11.1'/>

|-
!align=left {{table_heading_style}} |Knock-Out Phenotype
||
Chitobiose negative and Cellobiose negative
|-
!align=left {{table_heading_style}} |Regulation/Expression
||
transcription unit(s): [[:Category:Txn_unit:chbBCARFG|chbBCARFG]]<ref name='LIB:EcoCyc10.6'/>
|-
!align=left {{table_heading_style}} |Regulation/Activity
||
Repressor in the absence of inducer and activator in the presence of inducer.

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=421aa90e079fa326b6494f812ad13e79.5227.V46a99e92bc3a0&page=5227&pagename={{FULLPAGENAMEE}}&type=1&template=Quickview_table edit table] ||
|}

{{Quickview_table_help}}
<protect></protect>
===Notes===
{{BacktoTop}}

<noinclude>
ChbR was initially reported as a repressor of the ''chb'' operon. However later work showed that this protein is an activator as well as the repressor of the ''chb'' operon. The mutations in the ''chbR'' have also been reported to confer Cel+ phenotype to ''E. coli''.

==References==
{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>

chbR:Quickview

2009-01-16T17:57:40Z

Aashiq: Table edited by Aashiq via TableEdit

{{#css:Suppresslinks.css}}<css>{{:Suppresslinks.css}}</css>
<noinclude>{{TabsTop}}
{{Tab On|Quickview|chbR}}{{Tab|Gene|chbR}}{{Tab|Gene Product(s)|chbR}}{{Tab|Expression|chbR}}{{Tab|Evolution|chbR}}{{Tab|On One Page|chbR}}{{TabsBottom}}
{|
|- style="background-color:white; border:solid 2px #CCFFFF; text-align:center; white-space: nowrap;"
|{{Sub}}[[#References| References]]
|{{Sub}}[[Talk:{{PAGENAMEE}}| Suggestions]]
|}
</noinclude>


{|border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; border: 1px #aaa solid; border-collapse: collapse;"

|-
!align=left {{table_heading_style}} |Gene Name
||
[[chbR:Gene|''chbR]]'' (synonyms: ''ECK1733, b1735, JW1724, celD'')<ref name='LIB:Riley_2006'/>
|-
!align=left {{table_heading_style}} |Product(s)
||
[[chbR:Gene_Product(s)|ChbR product]]<ref name='LIB:Riley_2006'/>: DNA-binding transcriptional dual regulator product, B1735 product, CelD product
|-
!align=left {{table_heading_style}} |Description
||
ChbR transcriptional regulator<ref name='LIB:EcoCyc10.6'/> ChbR transcriptional dual regulator<ref name='LIB:EcoCyc11.1'/>

|-
!align=left {{table_heading_style}} |Knock-Out Phenotype
||
Chitobiose negative and Cellobiose negative
|-
!align=left {{table_heading_style}} |Regulation/Expression
||
transcription unit(s): [[:Category:Txn_unit:chbBCARFG|chbBCARFG]]<ref name='LIB:EcoCyc10.6'/>
|-
!align=left {{table_heading_style}} |Regulation/Activity
||
Repressor in the absence of inducer and activator in the presence of inducer.

|-class='sortbottom'
|[{{SERVER}}{{SCRIPTPATH}}?title=Special:TableEdit&id=421aa90e079fa326b6494f812ad13e79.5227.V46a99e92bc3a0&page=5227&pagename={{FULLPAGENAMEE}}&type=1&template=Quickview_table edit table] ||
|}

{{Quickview_table_help}}
<protect></protect>
===Notes===
{{BacktoTop}}

<noinclude>
==References==
{{BacktoTop}}
{{RefHelp}}
<references/>
</noinclude>