Chang B Y, Chen K Y, Wen Y D, Liao C T
Agricultural Biotechnology Laboratories, National Chung Hsing University, Taichung, Taiwan, Republic of China.
J Bacteriol. 1994 Jun;176(11):3102-10. doi: 10.1128/jb.176.11.3102-3110.1994.
The mutant sigA allele of Bacillus subtilis DB1005 was confirmed to be temperature sensitive (ts) and transferable among strains of B. subtilis by chromosomal transformation and gene conversion. This ts sigA allele had a pleiotropic effect on gene expression of DB1005. The induction of certain heat shock proteins in DB1005 was markedly less significant than that observed in the wild-type strain (DB2) under heat stress. In contrast, some proteins required for coping with oxidative stress and glucose starvation were induced abruptly in DB1005 but not in DB2. Heat induction of the groEL gene in vivo at both transcription and translation levels was much lower in DB1005 than in DB2. Besides, the putative sigma A-type promoter from the groESL operon of B. subtilis was able to be transcribed by the reconstituted sigma A RNA polymerase in vitro at both 37 and 49 degrees C. These results strongly suggest that the expression of the groEL gene of B. subtilis under heat stress is regulated at least in part by sigma A at the level of transcription. Our results also showed that DB1005 did not respond too differently from the wild type to ethanol stress, except after a relatively long exposure.
枯草芽孢杆菌DB1005的突变sigA等位基因被证实具有温度敏感性（ts），并可通过染色体转化和基因转换在枯草芽孢杆菌菌株间转移。这个ts sigA等位基因对DB1005的基因表达具有多效性影响。在热应激条件下，DB1005中某些热休克蛋白的诱导明显低于野生型菌株（DB2）。相反，DB1005中一些应对氧化应激和葡萄糖饥饿所需的蛋白质被突然诱导，而DB2中则没有。在体内，DB1005中groEL基因在转录和翻译水平上的热诱导都远低于DB2。此外，枯草芽孢杆菌groESL操纵子的假定sigma A型启动子在体外37℃和49℃时都能被重组的sigma A RNA聚合酶转录。这些结果有力地表明，枯草芽孢杆菌groEL基因在热应激下的表达至少部分在转录水平上受sigma A调控。我们的结果还表明，除了在相对长时间暴露后，DB1005对乙醇应激的反应与野生型没有太大差异。
