Institute of Biochemistry and Molecular Biology, School of Life Science, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Arch Microbiol. 2011 Sep;193(9):677-85. doi: 10.1007/s00203-011-0710-0. Epub 2011 May 4.
The Bacillus subtilis cell wall hydrolase LytE is involved in cell wall turnover and cell separation during vegetative growth. lytE transcription is known to be driven by a YycF-activated SigA-dependent promoter. The cell wall regulator SigI is an alternative sigma factor that has been shown to be heat stress-inducible and to be essential for survival of B. subtilis at high temperature. However, none of the previously identified target genes of SigI contribute to heat resistance. We now demonstrate that lytE expression is heat-inducible and that heat induction of lytE expression is strongly dependent on SigI. We have also found that the lytE mutant shows the same growth defect at high temperature as the sigI mutant. Introducing an extra copy of lytE into the sigI mutant could rescue its growth defect. Our data strongly suggest that SigI-dependent lytE expression under heat stress is important for heat survival of B. subtilis.
枯草芽孢杆菌细胞壁水解酶 LytE 参与了营养生长过程中的细胞壁周转和细胞分离。已知 lytE 转录由 YycF 激活的 SigA 依赖性启动子驱动。细胞壁调节剂 SigI 是一种替代 sigma 因子，已被证明可被热应激诱导，并且对枯草芽孢杆菌在高温下的存活至关重要。然而，SigI 的先前鉴定的靶基因都没有有助于耐热性。我们现在证明 lytE 的表达可被热诱导，并且 lytE 表达的热诱导强烈依赖于 SigI。我们还发现，lytE 突变体在高温下表现出与 sigI 突变体相同的生长缺陷。将 lytE 的额外拷贝引入 sigI 突变体中可以挽救其生长缺陷。我们的数据强烈表明，热应激下 SigI 依赖性 lytE 表达对枯草芽孢杆菌的耐热性生存至关重要。
