PMID:17981958
| Citation |
Fernández, M, Sánchez-Hidalgo, M, García-Quintáns, N, Martínez-Bueno, M, Valdivia, E, López, P and Maqueda, M (2008) Processing of as-48ABC RNA in AS-48 enterocin production by Enterococcus faecalis. J. Bacteriol. 190:240-50 |
|---|---|
| Abstract |
Enterocin AS-48 production and immunity characters are encoded by 10 genes (as-48ABCC(1)DD(1)EFGH) of the pMB2 plasmid from the Enterococcus faecalis S-48 strain. Among these, as-48A, encoding the AS-48 peptide, and the as-48BC genes constitute a cluster required for AS-48 biogenesis and full immunity. In this study, the levels of expression of this cluster have been altered by insertion and site-directed mutagenesis as well as by expression coupled to trans complementation. Phenotypic studies of the mutants have indicated cotranscription of the three genes and revealed that the inactivation of as-48B prevents the production of AS-48, thus confirming its essentiality in AS-48 biogenesis. These studies have also supported the involvement of as-48C in enterocin immunity. In addition, they established that the intergenic region between the as-48A and as-48B genes is decisive for AS-48 expression, since a 3-bp substitution, which should disrupt a potential 47-nucleotide complex secondary structure, resulted in a hypoproducing phenotype. Transcriptional analyses of the E. faecalis wild-type and mutant strains supports the possibility that the as-48ABC genes are transcribed from the P(A) promoter located upstream of as-48A. Moreover, analysis and bioinformatic predictions of RNA folding indicate that as-48ABC mRNA is processed at the secondary structure located between as-48A and as-48B. Thus, synthesis of the AS-48 peptide appears to be controlled at the posttranscriptional level and is uncoupled from as-48BC translation. This mechanism of genetic regulation has not been previously described for the regulation of bacteriocin expression in enterococci. |
| Links |
PubMed PMC2223719 Online version:10.1128/JB.01528-07 |
| Keywords |
Bacterial Proteins/genetics; Bacterial Proteins/immunology; Base Sequence; DNA, Bacterial/genetics; Enterococcus faecalis/genetics; Enterococcus faecalis/immunology; Enterococcus faecalis/pathogenicity; Escherichia coli/genetics; Gene Expression Regulation, Bacterial; Molecular Sequence Data; Nucleic Acid Conformation; Peptides/genetics; Peptides/immunology; Plasmids; RNA, Bacterial/chemistry; RNA, Bacterial/genetics; Recombinant Proteins/immunology; Recombinant Proteins/metabolism |
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