Lactococcus lactis uses MscL as its principal mechanosensitive channel
Lactococcus lactis uses MscL as its principal mechanosensitive channel
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DOI：
10.1074/jbc.m411732200
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发表时间：
2005-03-11
影响因子：
4.8
通讯作者：
Poolman, B
中科院分区：
文献类型：
--
作者：
Folgering, JHA;Moe, PC;Poolman, B
用生化、生理和电生理方法测定了乳酸乳球菌机械敏感通道的功能。膜片钳研究表明，当在大肠杆菌中表达或纯化基因产物并在蛋白脂质体中重组时，基因yncB和MSCL分别编码MSCs和MSCL样通道。然而，除非yncB在反式载体中表达，否则乳酸乳杆菌的野生型膜只显示MSCL活性。从MSCL中断突变体制备的膜不显示任何机械敏感通道活性，无论细胞是在低渗透压还是高渗透压介质中生长。在渗透压降档分析中，野生型细胞在外部高盐条件下存活并保留了20%内化的甘氨酸甜菜碱。另一方面，MSCL中断突变体保留了40%的内化甘氨酸甜菜碱，并在渗透压下降时显著降低了其存活率。这些数据强烈表明乳酸乳杆菌以MSCL作为主要的机械敏感溶质释放系统来保护渗透压降档条件下的细胞。
The functions of the mechanosensitive channels from Lactococcus lactis were determined by biochemical, physiological, and electrophysiological methods. Patch-clamp studies showed that the genes yncB and mscL encode MscS and MscL-like channels, respectively, when expressed in Escherichia coli or if the gene products were purified and reconstituted in proteoliposomes. However, unless yncB was expressed in trans, wild type membranes of L. lactis displayed only MscL activity. Membranes prepared from an mscL disruption mutant did not show any mechanosensitive channel activity, irrespective of whether the cells had been grown on low or high osmolarity medium. In osmotic downshift assays, wild type cells survived and retained 20% of the glycine betaine internalized under external high salt conditions. On the other hand, the mscL disruption mutant retained 40% of internalized glycine betaine and was significantly compromised in its survival upon osmotic downshifts. The data strongly suggest that L. lactis uses MscL as the main mechanosensitive solute release system to protect the cells under conditions of osmotic downshift.