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RpoS is directly controlled by ATP levels
Author(s) -
Peterson Celeste
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.995.8
Subject(s) - rpos , sigma factor , microbiology and biotechnology , citric acid cycle , escherichia coli , protein degradation , mutant , biochemistry , ubiquitin , biology , gtp' , protein turnover , chemistry , protein biosynthesis , gene , metabolism , gene expression , enzyme , promoter , rna polymerase
Many cells enter a state of dormancy when deprived of nutrients. For bacteria, this makes them more robust to environmental stresses. In Escherichia coli, reshaping the repertoire of proteins for stress resistance is mostly done by changing gene expression. The master regulator of this response, the sigma factor RpoS, regulates transcription of >;300 genes upon starvation. However, RpoS itself is controlled at the level of protein degradation: under exponential growth it is the most short‐lived protein in E. coli but upon carbon starvation degradation quickly ceases. The molecular steps leading from carbon starvation to a change in RpoS protein stability are not well understood. We systematically block key steps of glycolysis and the citric acid cycle and monitor the effect on RpoS degradation in vivo. Nutrient upshifts trigger RpoS degradation independently of protein synthesis by activating metabolic pathways that generate small energy molecules. Using metabolic mutants and inhibitors, we show that ATP but not GTP or NADH is necessary for RpoS degradation. In vitro reconstitution assays directly demonstrate that ClpXP fails to degrade RpoS but not other proteins at low ATP hydrolysis rates. These data suggest that cellular ATP levels directly control RpoS stability. Connecting ATP levels directly to degradation could provide a reliable and ultrafast signal for starvation.