Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4AX, UK.
Mol Microbiol. 2012 Dec;86(5):1031-5. doi: 10.1111/mmi.12059. Epub 2012 Oct 15.
Most bacteria surround their cytoplasmic membrane with a net-like, elastic heteropolymer, the peptidoglycan sacculus, to protect themselves from bursting due to the turgor and to maintain cell shape. It has been assumed that growing bacteria require peptidoglycan hydrolases to open meshes in the peptidoglycan net allowing the insertion of the newly synthesized material for surface expansion. However, peptidoglycan hydrolases essential for bacterial growth have long remained elusive. In this issue of Molecular Microbiology Singh et al. (2012) report the identification in Escherichia coli of three new DD-endopeptidases (Spr, YdhO and YebA) which are collectively required for peptidoglycan growth. Cells depleted of the three enzymes fail to incorporate new peptidoglycan, indicating that the cleavage of cross-links by the new endopeptidases is needed for surface growth of the sacculus. These results are corroborated by recent data showing that Bacillus subtilis cells require the DL-endopeptidase activity of CwlO or LytE for growth.
大多数细菌通过一个网状的、有弹性的杂聚物——肽聚糖囊来包围细胞质膜，以防止由于渗透压而破裂，并保持细胞形状。人们一直认为，生长中的细菌需要肽聚糖水解酶来打开肽聚糖网中的网格，以便插入新合成的物质进行表面扩展。然而，对于生长所必需的肽聚糖水解酶却一直难以捉摸。在本期的《分子微生物学》杂志上，Singh 等人（2012）报道了在大肠杆菌中鉴定出三种新的 DD-内肽酶（Spr、YdhO 和 YebA），它们共同参与肽聚糖的生长。缺乏这三种酶的细胞无法掺入新的肽聚糖，这表明新的内肽酶对交联的切割对于囊的表面生长是必需的。这些结果得到了最近的数据的证实，这些数据表明枯草芽孢杆菌细胞的生长需要 CwlO 或 LytE 的 DL-内肽酶活性。
