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. 2006 Nov;186(5):377-83. doi: 10.1007/s00203-006-0152-2. Epub 2006 Aug 5.
A translational lacZ fusion of the Bacillus subtilis mscL gene that encodes the mechanosensitive channel of large conductance (MscL) was expressed at significant levels during log phase growth of B. subtilis, and the level of mscL-lacZ expression was increased 1.5-fold by growth in medium with high salt (1 M NaCl). However, in growth media with either low or high salt, mscL-lacZ expression fell drastically beginning in the late log phase of growth, and fell to even lower levels during sporulation, although a significant amount of beta-galactosidase from mscL to lacZ was accumulated in the developing spore. Deletion of mscL had no effect on B. subtilis growth, sporulation or subsequent spore germination. The DeltamscL strain also grew as well as the wild-type parental strain in medium with 1.2 M NaCl. While log phase wild-type cells grown with 1.2 M NaCl survived a rapid 0.9 M osmotic downshift, log phase DeltamscL cells rapidly lost viability and lysed when subjected to this same osmotic downshift. However, by the early stationary phase of growth, DeltamscL cells had become resistant to a 0.9 M osmotic downshift.
编码大电导机械敏感通道（MscL）的枯草芽孢杆菌mscL基因的翻译型lacZ融合体在枯草芽孢杆菌对数生长期大量表达，并且在高盐（1 M NaCl）培养基中生长时，mscL-lacZ的表达水平增加了1.5倍。然而，在低盐或高盐生长培养基中，mscL-lacZ的表达从对数生长期后期开始急剧下降，并且在芽孢形成期间降至更低水平，尽管在发育中的孢子中积累了大量从mscL到lacZ的β-半乳糖苷酶。删除mscL对枯草芽孢杆菌的生长、芽孢形成或随后的孢子萌发没有影响。ΔmscL菌株在含有1.2 M NaCl的培养基中也能像野生型亲本菌株一样良好生长。当在含有1.2 M NaCl的培养基中生长的对数期野生型细胞经受快速的0.9 M渗透压下降时能够存活，但对数期的ΔmscL细胞在经受相同的渗透压下降时迅速失去活力并裂解。然而，到生长的早期稳定期，ΔmscL细胞已对0.9 M渗透压下降产生抗性。
