The vanG glycopeptide resistance operon from Enterococcus faecalis revisited.
Acquired VanG-type resistance to vancomycin (MIC = 16 micro g ml(-1)) but susceptibility to teicoplanin in Enterococcus faecalis BM4518 and WCH9 is due to the inducible synthesis of peptidoglycan precursors ending in d-alanine-d-serine. The vanG cluster, assigned to a chromosomal location, was composed of genes recruited from various van operons. The 3' end encoded VanG, a d-Ala:d-Ser ligase, VanXY(G), a putative bifunctional d,d-peptidase and VanT(G), a serine racemase: VanG and VanT(G) were implicated in the synthesis of d-Ala:d-Ser as in VanC- and VanE-type strains. Upstream from the structural genes for these proteins were vanW(G) with unknown function and vanY(G) containing a frameshift mutation which resulted in premature termination of the encoded protein and accounted for the lack of UDP-MurNAc-tetrapeptide in the cytoplasm. Without the frameshift mutation, VanY(G) had homology with Zn2+ dependent d,d-carboxypeptidases. The 5' end of the gene cluster contained three genes vanU(G), vanR(G) and vanS(G) encoding a putative regulatory system, which were co-transcribed constitutively from the PY(G) promoter, whereas transcription of vanY(G),W(G),G,XY(G),T(G) was inducible and initiated from the P(YG) promoter. Transfer of VanG-type glycopeptide resistance to E. faecalis JH2-2 was associated with the movement, from chromosome to chromosome, of genetic elements of c. 240 kb carrying also ermB-encoded erythromycin resistance. Sequence determination of the flanking regions of the vanG cluster in donor and transconjugants revealed the same 4 bp direct repeats and 22 bp imperfect inverted repeats that delineated the large element.[1]References
- The vanG glycopeptide resistance operon from Enterococcus faecalis revisited. Depardieu, F., Bonora, M.G., Reynolds, P.E., Courvalin, P. Mol. Microbiol. (2003) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
