Reynolds P E
Department of Biochemistry, University of Cambridge, UK.
Cell Mol Life Sci. 1998 Apr;54(4):325-31. doi: 10.1007/s000180050159.
Resistance to glycopeptide antibiotics in enterococci results from the synthesis of peptidoglycan precursors with low affinity for these antibiotics. The resistance proteins are encoded on transposons in VanA and VanB type enterococci and are involved in regulation, synthesis of new resistant precursors and elimination of wild-type sensitive precursors by hydrolysis of D-alanyl-D-alanine (D,D-peptidase activity encoded by vanX) and removal of D-alanine from UDP-N-acetylmuramyl (UDP-MurNAc)-pentapeptide (D,D-carboxypept-idase activity encoded by vanY). The substrate specificities of VanX and VanY ensure that essentially only precursors with low affinity for glycopeptide antibiotics are available for peptidoglycan synthesis in strains induced to resistance.
肠球菌对糖肽类抗生素的耐药性源于合成对这些抗生素亲和力低的肽聚糖前体。耐药蛋白由VanA和VanB型肠球菌中的转座子编码，参与调节、新的耐药前体的合成以及通过水解D-丙氨酰-D-丙氨酸（由vanX编码的D，D-肽酶活性）消除野生型敏感前体，并从UDP-N-乙酰胞壁酰（UDP-MurNAc）-五肽中去除D-丙氨酸（由vanY编码的D，D-羧肽酶活性）。VanX和VanY的底物特异性确保在诱导产生耐药性的菌株中，基本上只有对糖肽类抗生素亲和力低的前体可用于肽聚糖合成。
