Gittins J R, Phoenix D A, Pratt J M
Department of Biochemistry, University of Liverpool, UK.
FEMS Microbiol Rev. 1994 Jan;13(1):1-12. doi: 10.1111/j.1574-6976.1994.tb00031.x.
The major penicillin-binding proteins (PBPs) of Escherichia coli play vital roles in cell wall biosynthesis and are located in the inner membrane. The high M(r) PBPs 1A, 1B, 2 and 3 are essential bifunctional transglycosylases/transpeptidases which are thought to be type II integral inner membrane proteins with their C-terminal enzymatic domains projecting into the periplasm. The low M(r) PBP4 is a DD-carboxypeptidase/endopeptidase, whereas PBPs 5 and 6 are DD-carboxypeptidases. All three low M(r) PBPs act in the modification of peptidoglycan to allow expansion of the sacculus and are thought to be periplasmic proteins attached with varying affinities to the inner membrane via C-terminal amphiphilic alpha-helices. It is possible that the PBPs and other inner membrane proteins form a peptidoglycan synthesizing complex to coordinate their activities.
大肠杆菌的主要青霉素结合蛋白（PBPs）在细胞壁生物合成中发挥着至关重要的作用，且位于内膜中。高分子量的PBPs 1A、1B、2和3是必需的双功能转糖基酶/转肽酶，被认为是II型整合内膜蛋白，其C端酶结构域伸向周质。低分子量的PBP4是一种DD-羧肽酶/内肽酶，而PBPs 5和6是DD-羧肽酶。所有这三种低分子量的PBPs都参与肽聚糖的修饰，以使细胞壁能够扩展，并且被认为是通过C端两亲性α-螺旋以不同亲和力附着于内膜的周质蛋白。PBPs与其他内膜蛋白有可能形成一个肽聚糖合成复合体来协调它们的活性。
