TREHALOSE SYNTHESIS GENES ARE CONTROLLED BY THE PUTATIVE SIGMA-FACTOR ENCODED BY RPOS AND ARE INVOLVED IN STATIONARY-PHASE THERMOTOLERANCE IN ESCHERICHIA-COLI

The rpoS (katF) gene of Escherichia coli encodes a putative sigma factor (sigma(s)) required for the expression of a variety of stationary phase-induced genes, lor the development of stationary-phase stress resistance, and for long-term starvation survival (R. Lange and R. Hengge-Aronis, Mol. Microbiol. 5:49-59, 1991). Here we show that the genes otsA, otsB, treA, and osmB, previously known to be osmotically regulated, are also induced during transition into stationary phase in a sigma(s)-dependent manner. otsA and otsB, which encode trehalose-6-phosphate synthase and trehalose-6-phosphate phosphatase, respectively, are involved in sigma(s)-dependent stationary-phase thermotolerance. Neither sigma(s) nor trehalose, however, is required for the development of adaptive thermotolerance in growing cells, which might be controlled by sigma(E).