Purification and characterization of the VanB ligase associated with type B vancomycin resistance in Enterococcus faecalis V583

Abstract

Acquired resistance to glycopeptides in enterocoeci is associated with the production of D-Akinine: D-Alanme Iigase-related proteins. The VanA protein associated with high-level vancomycin and teicoplanin resistance (VanA phenotype) synthesizes a new peptidoglycau precursor, D-alanine-n-lactate, that has reduced glycopeptide atlinity. Production of a similar protein, VanB, is induced in strains that display variable levels of vancomycin resistance but remain susceptible to teicoplanin (VanB phenotype). This paper describes the over-production, purification and characterization of VanB. Comparison of kinetic parameters of the two Van enzymes suggests that differences in catalytic efficiency could account, at least in part, for the various levels of vaucomycin resistance.

Mutations leading to increased levels of resistance to glycopeptide antibiotics in VanB‐type enterococci

“…These conditions also appear to apply to the vanB gene cluster, since increased glycopeptide resistance in the mutants studied was always associated with increased synthesis of UDP-MurNAc-pentadepsipeptide to the detriment of UDP-MurNAc-pentapeptide, following alteration of the regulation of the resistance genes or of the activity of the host D-Ala:D-Ala ligase. As a concluding remark, it is perhaps worth noting that synthesis of the dipeptide is not expected to be totally eliminated even in a ddl null mutant, ᮊ 1997 Blackwell Science Ltd, Molecular Microbiology, 25, [93][94][95][96][97][98][99][100][101][102][103][104][105] Regulation of glycopeptide resistance 101 since VanB has both D-Ala:D-Lac and D-Ala:D-Ala ligase activity (Meziane-Cherif et al, 1994).…”

Gain of d-Alanyl-d-lactate or d-Lactyl-d-alanine Synthetase Activities in Three Active-Site Mutants of the Escherichia coli d-Alanyl-d-alanine Ligase B

“…VanA (and related VanB;Meziane-Cherif et al, 1994) has been the only case heretofore of an ATP-dependent depsipeptide ligase. Figure 4C shows that under the given conditions VanA produces a 1:1 ratio of D-Ala-D-Hbut/DAla-D-Ala at pH 7.5.…”

Regulation of VanB-type vancomycin resistance gene expression by the VanS(B)-VanR (B) two-component regulatory system in Enterococcus faecalis V583

“…The vanB gene is located on large conjugative chromosomal elements (from 90 to 250 kb) (33) or on plasmids (45). Structurally, VanB is closely related to VanA (76% amino acid identity) (15) and has similar catalytic properties (30). Produc-tion of VanB and of a D,D-carboxypeptidase is induced by VM (20).…”