Tojo Shigeo, Matsunaga Masayuki, Matsumoto Takashi, Kang Choong-Min, Yamaguchi Hirotake, Asai Kei, Sadaie Yoshito, Yoshida Ken-ichi, Fujita Yasutaro
Department of Biotechnology, Faculty of Life Science and Biotechnology, Fukuyama University, 985 Sanzo, Higashimura-cho, Fukuyama, Hiroshima 729-0292.
J Biochem. 2003 Dec;134(6):935-46. doi: 10.1093/jb/mvg225.
We investigated the organization and expression of the Bacillus subtilis sigY operon, the first gene of which codes for sigmaY, a member of the extracytoplasmic function (ECF) family of sigma factors. The sigY operon, comprising six genes (sigY, yxlC, D, E, F, and G), was induced upon nitrogen starvation; it was continuously transcribed from the 31st base upstream of sigY to a neighboring convergent gene, yxlH, resulting in a 4.2-kb mRNA. The expression of the sigY operon was also positively autoregulated through sigmaY, suggesting that its transcription is likely to be directed by sigmaY. Deletion analysis of the sigY promoter, which was localized by primer extension, revealed the promoter region of sigY with the "-10" and "-35" sequences of CGTC and TGAACG, respectively. The latter sequence was distinct from those recognized by sigmaW, sigmaX, and sigmaM. The sigmaY-directed transcription of sigY was under negative regulation involving YxlD. sigY disruption affected sporulation induced by nitrogen starvation, but sigY induction upon nitrogen starvation was not associated with the sporulation process. The organization and function of the sigY operon are significantly conserved in several microorganisms living in adverse living environments.
我们研究了枯草芽孢杆菌sigY操纵子的组织和表达情况，该操纵子的第一个基因编码σY，它是胞外功能（ECF）家族σ因子的成员。sigY操纵子由六个基因（sigY、yxlC、D、E、F和G）组成，在氮饥饿时被诱导；它从sigY上游第31个碱基处持续转录至相邻的同向基因yxlH，产生一条4.2 kb的mRNA。sigY操纵子的表达也通过σY进行正自调控，这表明其转录可能由σY指导。通过引物延伸定位的sigY启动子的缺失分析，揭示了sigY的启动子区域，其“-10”和“-35”序列分别为CGTC和TGAACG。后一个序列与σW、σX和σM识别的序列不同。sigY由σY指导的转录受到涉及YxlD的负调控。sigY缺失影响了氮饥饿诱导的芽孢形成，但氮饥饿时sigY的诱导与芽孢形成过程无关。sigY操纵子的组织和功能在生活在恶劣生存环境中的几种微生物中显著保守。
