Wahome Paul G, Setlow Peter
Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3305, USA.
Arch Microbiol. 2008 Jan;189(1):49-58. doi: 10.1007/s00203-007-0292-z. Epub 2007 Jul 31.
Previous work has shown that the mechanosensitive (MS) channel of large conductance (MscL) is essential for preventing lysis of Bacillus subtilis log phase cells upon a rapid, severe osmotic downshock. Growing cells of B. subtilis strains lacking MscL and one or more putative MS channel proteins of small conductance (YhdY, YkuT and YfkC) showed even higher sensitivity to an osmotic downshock. The effect was greatest for a strain lacking MscL and YkuT, and a strain lacking all four MS channel proteins had a similar phenotype. These defects were complemented by expression of either MscL or YkuT in trans. All MS channel mutant strains ultimately became resistant to osmotic downshock in stationary phase but at varying times, with mscL ykuT strains taking the longest time to become resistant. Expression of beta-galactosidase from gene fusions to lacZ showed modest expression of ykuT and lower levels of expression of yhdY and yfkC when strains were grown in medium containing high salt. Sporulation of all MS channel mutant strains was normal, and the mutant spores germinated normally with L-alanine or dodecylamine.
先前的研究表明，大电导机械敏感（MS）通道（MscL）对于防止枯草芽孢杆菌对数期细胞在快速、严重的渗透压骤降时裂解至关重要。缺乏MscL以及一种或多种假定的小电导MS通道蛋白（YhdY、YkuT和YfkC）的枯草芽孢杆菌菌株的生长细胞对渗透压骤降表现出更高的敏感性。对于缺乏MscL和YkuT的菌株，这种影响最为显著，而缺乏所有四种MS通道蛋白的菌株具有相似的表型。通过反式表达MscL或YkuT可弥补这些缺陷。所有MS通道突变菌株最终在稳定期对渗透压骤降产生抗性，但时间各不相同，mscL ykuT菌株产生抗性所需的时间最长。当菌株在含高盐的培养基中生长时，与lacZ基因融合的β-半乳糖苷酶的表达显示YkuT表达适度，YhdY和YfkC的表达水平较低。所有MS通道突变菌株的孢子形成正常，并且突变孢子在L-丙氨酸或十二烷基胺作用下正常萌发。
