Booth I R, Louis P
Department of Molecular & Cell Biology, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, AB25 2ZD, UK.
Curr Opin Microbiol. 1999 Apr;2(2):166-9. doi: 10.1016/s1369-5274(99)80029-0.
When Escherichia coli cells are subject to hypoosmotic shock they are subject to substantial flows of water that can be equivalent to a 4-5-fold increase in the pressure exerted from the cytoplasm on the membrane and peptidoglycan wall. The recently described aquaporin that facilitates rapid water movement across the cytoplasmic membrane is repressed during growth at high osmolarity. This may enable the cell to reduce the rate of pressure build up during transitions from high to low osmolarity. The presence of multiple mechanosensitive channels in the E. coli cell membrane is well documented. The recent identification of genes that inactivate the MscL and MscS channels has established their role in releasing the pressure built up by hypoosmotic shock. The isolation of specific mutations and the structural studies on MscL now pave the way to a molecular understanding of the mechanism of activation of mechanosensitive channels.
当大肠杆菌细胞受到低渗冲击时，它们会经历大量的水流，这相当于细胞质对细胞膜和肽聚糖壁施加的压力增加4至5倍。最近描述的促进水快速穿过细胞质膜的水通道蛋白在高渗透压下生长时受到抑制。这可能使细胞在从高渗透压向低渗透压转变期间降低压力积累的速率。大肠杆菌细胞膜中存在多个机械敏感通道，这一点已有充分记录。最近对使MscL和MscS通道失活的基因的鉴定，确定了它们在释放低渗冲击所积累压力方面的作用。特定突变的分离以及对MscL的结构研究，现在为从分子层面理解机械敏感通道的激活机制铺平了道路。
