Peptidoglycan synthetic activities in membranes of Escherichia coli caused by overproduction of penicillin-binding protein 2 and rodA protein.
Peptidoglycan synthetic activities in membranes of Escherichia coli caused by overproduction of penicillin-binding protein 2 and rodA protein.
复制标题
青霉素结合蛋白 2 和 rodA 蛋白过量产生导致大肠杆菌膜中肽聚糖的合成活性。
DOI：
10.1016/s0021-9258(19)62717-1
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Michio MatsuhashiS
中科院分区：
文献类型：
--
作者：
F. Ishino;W. Park;Shigeo Tomiokag;Shigeo TamakiSg;Ichiro TakaseSn;Kiyohiko KunugitaS;H. Matsuzawa;S. Asoh;T. Ohta;Brian;Spratt;Michio MatsuhashiS
已知青霉素结合蛋白（PBP）-2和RodA蛋白在决定大肠杆菌细胞的杆状中起作用。肽聚糖的生物合成反应需要这两种蛋白质被证明在膜部分制备的E。过量产生这两种蛋白质且缺乏PBP-1B活性（正常大肠杆菌中主要的肽聚糖合成酶活性）的大肠杆菌菌株。coli膜）。在高浓度头孢美唑的存在下，由UDP-N-乙酰胞壁酰五肽和UDP-N-乙酰葡糖胺合成交联肽聚糖，所述头孢美唑抑制除PBP-2之外的所有PBP。肽聚糖通过脂质中间体合成，并显示高达30%的交联。交联反应被脒基青霉素、美西林和其他对PBP-2具有高亲和力的β-内酰胺抗生素强烈抑制，但不被对PBP-2具有非常低亲和力的β-内酰胺抑制。肽聚糖的形成需要膜中存在高水平的PBP-2和RodA蛋白，但尚不清楚这两种蛋白中的哪一种主要负责聚糖链的延伸（转糖基化）。然而，交联反应对特定β-内酰胺抗生素的敏感性强烈表明它是由PBP-2催化的。膜的转糖基酶活性对恩拉霉素和万古霉素敏感，并且在被高浓度的螯合剂极大地刺激时是不寻常的。
Penicillin-binding protein (PBP)-2 and the RodA protein are known to function in determining the rod shape of Escherichia coli cells. Peptidoglycan biosynthetic reactions that required these two proteins were demonstrated in the membrane fraction prepared from an E. coli strain that overproduced both of these two proteins and which lacked PBP-1B activity (the major peptidoglycan synthetase activity in the normal E. coli membranes). The cross-linked peptidoglycan was synthesized from UDP-N-acetylmuramylpentapeptide and UDP-N-acetylglucosamine in the presence of a high concentration of cefmetazole that inhibited all of PBPs except PBP-2. The peptidoglycan was synthesized via a lipid intermediate and showed up to 30% cross-linking. The cross-linking reaction was strongly inhibited by the amidinopenicillin, mecillinam, and by other beta-lactam antibiotics that have a high affinity for PBP-2, but not by beta-lactams that had very low affinity for PBP-2. The formation of peptidoglycan required the presence of high levels of both PBP-2 and the RodA protein in the membranes, but it is unclear which of the two proteins was primarily responsible for the extension of the glycan chains (transglycosylation). However, the sensitivity of the cross-linking reaction to specific beta-lactam antibiotics strongly suggested that it was catalyzed by PBP-2. The transglycosylase activity of the membranes was sensitive to enramycin and vancomycin and was unusual in being stimulated greatly by a high concentration of a chelating agent.