Casadewall B, Courvalin P
Unité des Agents Antibactériens, Institut Pasteur, 75724 Paris Cedex 15, France.
J Bacteriol. 1999 Jun;181(12):3644-8. doi: 10.1128/JB.181.12.3644-3648.1999.
VanD-type resistance to glycopeptides in Enterococcus faecium BM4339 is due to constitutive synthesis of D-alanyl-D-lactate-terminating peptidoglycan precursors (B. Périchon, P. Reynolds, and P. Courvalin, Antimicrob. Agents Chemother. 41:2016-2018, 1997). The sequence of a 5,780-bp fragment was determined and revealed six open reading frames. The 3' distal part encoded the VanHD dehydrogenase, the VanD ligase, and the VanXD DD-dipeptidase, which were highly similar to the corresponding proteins in VanA and VanB types of resistance. The deduced VanYD protein was homologous to penicillin-binding proteins that display DD-carboxypeptidase activity. The 5' end coded for the putative VanRD-VanSD two-component regulatory system. Due to a frameshift mutation in the chromosomal ddl gene, BM4339 produced an impaired D-alanine:D-alanine ligase. However, since expression of the resistance genes is constitutive, growth of E. faecium BM4339 was not dependent on the presence of glycopeptides in the culture medium.
粪肠球菌BM4339中VanD型糖肽抗性是由于组成型合成D-丙氨酰-D-乳酸终止的肽聚糖前体（B. Périchon、P. Reynolds和P. Courvalin，《抗菌剂与化疗》41:2016 - 2018，1997）。测定了一个5780 bp片段的序列，发现有六个开放阅读框。3'端远端部分编码VanHD脱氢酶、VanD连接酶和VanXD DD-二肽酶，它们与VanA和VanB型抗性中的相应蛋白质高度相似。推导的VanYD蛋白与具有DD-羧肽酶活性的青霉素结合蛋白同源。5'端编码假定的VanRD-VanSD双组分调节系统。由于染色体ddl基因中的移码突变，BM4339产生了有缺陷的D-丙氨酸:D-丙氨酸连接酶。然而，由于抗性基因的表达是组成型的，粪肠球菌BM4339的生长不依赖于培养基中糖肽的存在。
