New Family of Regulators in the Environmental Signaling Pathway Which Activates the General Stress Transcription Factor ς B of Bacillus subtilis

作者：Samina Akbar, Tatiana A. Gaidenko, Choong Min Kang, Mary O’Reilly, Kevin M. Devine, Chester W. Price · 发表于：Journal of Bacteriology · 年份：2001 · DOI：10.1128/jb.183.4.1329-1338.2001 · 被引用次数：153 · 研究领域：Bacterial Genetics and Biotechnology、Fungal and yeast genetics research、Bacteriophages and microbial interactions

Expression of the general stress regulon of Bacillus subtilis is controlled by the alternative transcription factor sigma(B), which is activated when cells encounter growth-limiting energy or environmental stresses. The RsbT serine-threonine kinase is required to convey environmental stress signals to sigma(B), and this kinase activity is magnified in vitro by the RsbR protein, a positive regulator important for full in vivo response to salt or heat stress. Previous genetic analysis suggested that RsbR function is redundant with other unidentified regulators. A search of the translated B. subtilis genome found six paralogous proteins with significant similarity to RsbR: YetI, YezB, YkoB, YojH, YqhA, and YtvA. Their possible regulatory roles were investigated using three different approaches. First, genetic analysis found that null mutations in four of the six paralogous genes have marked effects on the sigma(B) environmental signaling pathway, either singly or in combination. The two exceptions were yetI and yezB, adjacent genes which appear to encode a split paralog. Second, biochemical analysis found that YkoB, YojH, and YqhA are specifically phosphorylated in vitro by the RsbT environmental signaling kinase, as had been previously shown for RsbR, which is phosphorylated on two threonine residues in its C-terminal region. Both residues are conserved in the three phosphorylated paralogs but are absent in the ones that were not substrates of RsbT: YetI and YezB, each of which...