Trehalose Is Not Relevant for In Vivo Activity of ςS-Containing RNA Polymerase in Escherichia coli |
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Authors: | Jens Germer Andrea Muffler and Regine Hengge-Aronis |
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Institution: | Department of Biology, University of Konstanz, 78457 Konstanz, Germany |
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Abstract: | The ςS- and ς70-associated forms of RNA polymerase core enzyme (E) of Escherichia coli have very similar promoter recognition specificities in vitro. Nevertheless, the in vivo expression of many stress response genes is strongly dependent on ςS. Based on in vitro assays, it has recently been proposed that the disaccharide trehalose specifically stimulates the formation and activity of EςS and thereby contributes to promoter selectivity (S. Kusano and A. Ishihama, J. Bacteriol. 179:3649–3654, 1997). However, we demonstrate here that a trehalose-free otsA mutant exhibits growth phase-related and osmotic induction of various ςS-dependent genes which is indistinguishable from that of an otherwise isogenic wild-type strain and that stationary-phase cells do not accumulate trehalose (even though the trehalose-synthesizing enzymes are induced). We conclude that in vivo trehalose does not play a role in the expression of ςS-dependent genes and therefore also not in sigma factor selectivity at the promoters of these genes. |
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