Vollmer Waldemar, Bertsche Ute
Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Catherine Cookson Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
Biochim Biophys Acta. 2008 Sep;1778(9):1714-34. doi: 10.1016/j.bbamem.2007.06.007. Epub 2007 Jun 16.
The periplasmic murein (peptidoglycan) sacculus is a giant macromolecule made of glycan strands cross-linked by short peptides completely surrounding the cytoplasmic membrane to protect the cell from lysis due to its internal osmotic pressure. More than 50 different muropeptides are released from the sacculus by treatment with a muramidase. Escherichia coli has six murein synthases which enlarge the sacculus by transglycosylation and transpeptidation of lipid II precursor. A set of twelve periplasmic murein hydrolases (autolysins) release murein fragments during cell growth and division. Recent data on the in vitro murein synthesis activities of the murein synthases and on the interactions between murein synthases, hydrolases and cell cycle related proteins are being summarized. There are different models for the architecture of murein and for the incorporation of new precursor into the sacculus. We present a model in which morphogenesis of the rod-shaped E. coli is driven by cytoskeleton elements competing for the control over the murein synthesis multi-enzyme complexes.
周质中的胞壁质（肽聚糖）囊泡是一种巨大的大分子，由聚糖链和短肽交联而成，完全包围着细胞质膜，以保护细胞免受因内部渗透压导致的裂解。用溶菌酶处理囊泡可释放出50多种不同的胞壁肽。大肠杆菌有六种胞壁质合成酶，它们通过脂质II前体的转糖基化和转肽作用来扩大囊泡。一组12种周质胞壁质水解酶（自溶素）在细胞生长和分裂过程中释放胞壁质片段。本文总结了关于胞壁质合成酶体外胞壁质合成活性以及胞壁质合成酶、水解酶与细胞周期相关蛋白之间相互作用的最新数据。关于胞壁质的结构以及新前体掺入囊泡的方式有不同的模型。我们提出了一个模型，其中杆状大肠杆菌的形态发生是由细胞骨架元件竞争对胞壁质合成多酶复合物的控制所驱动的。
