Analysis of the gene cluster involved in production and immunity of the peptide antibiotic AS‐48 in Enterococcus faecalis

Publisher Website
Google Scholar
Abstract
A region of 7.8 kb of the plasmid pMB2 from Enterococcus faecalis S‐48 carrying the information necessary for production and immunity of the peptide antibiotic AS‐48 has been cloned and sequenced. It contains the as‐48A structural gene plus five open reading frames (as‐48B, as‐48C, as‐48C1, as‐48D and as‐48D1 ). Besides As‐48D, all the predicted gene products are basic hydrophobic proteins with potential membrane‐spanning domains (MSDs). None of them shows any homology with protein sequences stored in databanks, except for As‐48D, which shows similarity to the C‐terminal domain of ABC transporters and contains a highly conserved ATP‐binding site. The gene products of as‐48B, as‐48C, as‐48C1 and as‐48D are thought to be involved in AS‐48 production and secretion. The only gene able to provide resistance to AS‐48 by itself is as‐48D1. Immunity also seems to be enhanced at least by the products of as‐48B, as‐48C1 and as‐48D genes. Transcription analysis using probes derived from the different ORFs revealed two large (3.5 and 2.7 kb) mRNAs, suggesting that the different genes are organized in two constitutive operons.
Keywords