Dataset Information

Molecular characterization of Enterococcus faecalis N06-0364 with low-level vancomycin resistance harboring a novel D-Ala-D-Ser gene cluster, vanL.

ABSTRACT: Enterococcus faecalis N06-0364, exhibiting a vancomycin MIC of 8 microg/ml, was found to harbor a novel D-Ala-D-Ser gene cluster, designated vanL. The vanL gene cluster was similar in organization to the vanC operon, but the VanT serine racemase was encoded by two separate genes, vanTm(L) (membrane binding) and vanTr(L) (racemase).

SUBMITTER: Boyd DA

PROVIDER: S-EPMC2443935 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature

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Molecular characterization of Enterococcus faecalis N06-0364 with low-level vancomycin resistance harboring a novel D-Ala-D-Ser gene cluster, vanL.

Boyd David A DA Willey Barbara M BM Fawcett Darlene D Gillani Nazira N Mulvey Michael R MR

Antimicrobial agents and chemotherapy 20080505 7

Enterococcus faecalis N06-0364, exhibiting a vancomycin MIC of 8 microg/ml, was found to harbor a novel D-Ala-D-Ser gene cluster, designated vanL. The vanL gene cluster was similar in organization to the vanC operon, but the VanT serine racemase was encoded by two separate genes, vanTm(L) (membrane binding) and vanTr(L) (racemase). ...[more]

PMID: 18458129

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Project description:Enterococcus faecium clinical isolates A902 and BM4538, which were resistant to relatively high levels of vancomycin (128 and 64 microg/ml, respectively) and to low levels of teicoplanin (4 microg/ml), and Enterococcus faecalis clinical isolates BM4539 and BM4540, which were resistant to moderate levels of vancomycin (16 microg/ml) and susceptible to teicoplanin (0.25 microg/ml), were studied. They were constitutively resistant by synthesis of peptidoglycan precursors ending with d-alanyl-d-lactate and harbored a chromosomal vanD gene cluster which was not transferable by conjugation to other enterococci. VanX(D) activity, which is not required in the absence of d-Ala-d-Ala, was low in the four strains, although none of the conserved residues was mutated; and the constitutive VanY(D) activity in the membrane fractions was inhibited by penicillin G. The mutations E(13)G in the region of d-alanine:d-alanine ligase (which is implicated in d-Ala1 binding in A902) and S(319)N of the serine involved in ATP binding in BM4538 and a 7-bp insertion at different locations in BM4539 and BM4540 (which led to putative truncated proteins) led to the production of an impaired enzyme and accounted for the lack of d-Ala-d-Ala-containing peptidoglycan precursors. The same 7-bp insertion in vanS(D) of BM4539 and BM4540 and a 1-bp deletion in vanS(D) of A902, which in each case led to a putative truncated and presumably nonfunctional protein, could account for the constitutive resistance. Strain BM4538, with a functional VanS(D), had a G(140)E mutation in VanR(D) that could be responsible for constitutive glycopeptide resistance. This would represent the first example of constitutive van gene expression due to a mutation in the structural gene for a VanR transcriptional activator. Study of these four additional strains that could be distinguished on the basis of their various assortments of mutations confirmed that all VanD-type strains isolated so far have mutations in the ddl housekeeping gene and in the acquired vanS(D) or vanR(D) gene that lead to constitutive resistance to vancomycin.

Dataset Information

Molecular characterization of Enterococcus faecalis N06-0364 with low-level vancomycin resistance harboring a novel D-Ala-D-Ser gene cluster, vanL.

Publications

Molecular characterization of Enterococcus faecalis N06-0364 with low-level vancomycin resistance harboring a novel D-Ala-D-Ser gene cluster, vanL.

Similar Datasets

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