PMID:19458652
| Citation |
Wang, X, Kim, Y and Wood, TK (2009) Control and benefits of CP4-57 prophage excision in Escherichia coli biofilms. ISME J 3:1164-79 |
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| Abstract |
Earlier, we discovered that the global regulator, Hha, is related to cell death in biofilms and regulates cryptic prophage genes. Here, we show that Hha induces excision of prophages, CP4-57 and DLP12, by inducing excision genes and by reducing SsrA synthesis. SsrA is a tmRNA that is important for rescuing stalled ribosomes, contains an attachment site for CP4-57 and is shown here to be required for CP4-57 excision. These prophages impact biofilm development, as the deletion of 35 genes individually of prophages, CP4-57 and DLP12, increase biofilm formation up to 17-fold, and five genes decrease biofilm formation up to sixfold. In addition, CP4-57 excises during early biofilm development but not in planktonic cells, whereas DLP12 excision was detected at all the developmental stages for both biofilm and planktonic cells. CP4-57 excision leads to a chromosome region devoid of prophage and to the formation of a phage circle (which is lost). These results were corroborated by a whole-transcriptome analysis that showed that complete loss of CP4-57 activated the expression of the flg, flh and fli motility operons and repressed expression of key enzymes in the tricarboxylic acid cycle and of enzymes for lactate utilization. Prophage excision also results in the expression of cell lysis genes that reduce cell viability (for example, alpA, intA and intD). Hence, defective prophages are involved in host physiology through Hha and in biofilm formation by generating a diversified population with specialized functions in terms of motility and nutrient metabolism. |
| Links |
PubMed PMC2754048 Online version:10.1038/ismej.2009.59 |
| Keywords |
Bacteriolysis; Biofilms; Coliphages/genetics; Coliphages/growth & development; Coliphages/physiology; Colony Count, Microbial; DNA, Bacterial/chemistry; DNA, Bacterial/genetics; DNA-Binding Proteins/physiology; Escherichia coli/genetics; Escherichia coli/physiology; Escherichia coli/virology; Escherichia coli Proteins/physiology; Gene Expression Profiling; Host-Pathogen Interactions; Molecular Sequence Data; Prophages/genetics; Prophages/growth & development; Prophages/physiology; RNA, Bacterial/physiology; Sequence Analysis, DNA; Virus Activation |
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Significance
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By carefully deleting a whole prophage (while not altering surrounding DNA), this manuscript is one of the first to show a significant phenotype (e.g., increase in growth rate and decrease in motility) for a cryptic prophage in a bacterium, and it is important in that it explores the control of the cryptic prophage CP4-57 via the host protein Hha[1]. The manuscript also shows that cryptic prophage influence biofilm formation[1]. Prophage-like elements and prophage remnants have been identified in almost all sequenced bacterial genomes, and can constitute 10-20% of a bacterium’s genome. CP4-57 is a putative defective prophage with 22 genes and four pseudogenes; however, it lacks both a signature capsid and assembly gene. Hha is a small transcriptional regulator (8 kDa) that is induced in biofilms[2] and that influences biofilm formation[3]; Hha overexpression reduces biofilm formation by increasing biofilm dispersal[4]. Rather than binding to specific DNA sequences, Hha exhibits non-specific DNA binding. Hha binds in vivo to 15 genes or intergenic regions of CP4-57 and DLP12 including regions close to the prophage attachment (att) sites and that Hha activates the prophage lytic genes alpA, rzpD, appY and yfjZ, as well as induces plaque formation and decreases cell viability[4].
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References
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- ↑ 1.0 1.1 Wang, X et al. (2009) Control and benefits of CP4-57 prophage excision in Escherichia coli biofilms. ISME J 3 1164-79 PubMed
- ↑ Ren, D et al. (2004) Gene expression in Escherichia coli biofilms. Appl. Microbiol. Biotechnol. 64 515-24 PubMed
- ↑ Barrios, AF et al. (2006) Hha, YbaJ, and OmpA regulate Escherichia coli K12 biofilm formation and conjugation plasmids abolish motility. Biotechnol. Bioeng. 93 188-200 PubMed
- ↑ 4.0 4.1 García-Contreras, R et al. (2008) Protein translation and cell death: the role of rare tRNAs in biofilm formation and in activating dormant phage killer genes. PLoS ONE 3 e2394 PubMed
