Nucleoid proteins stimulate stringently controlled bacterial promoters: a link between the cAMP-CRP and the (p)ppGpp regulons in Escherichia coli.
We report that the H-NS nucleoid protein plays a positive role in the expression of stringently regulated genes in Escherichia coli. Bacteria lacking both H-NS and the paralog StpA show reduced growth rate. Colonies displaying an increased growth rate were isolated, and mapping of a suppressor mutation revealed a base pair substitution in the spoT gene. The spoT(A404E) mutant showed low ppGpp synthesizing ability. The crp gene, which encodes the global regulator CRP, was subject to negative stringent regulation. The stable RNA/protein ratio in an hns, stpA strain was decreased, whereas it was restored in the suppressor strain. Our findings provide evidence of a direct link between the cAMP-CRP modulon and the stringent response.
Johansson
J
J
Department of Microbiology, Umeå University, Sweden.
Balsalobre
C
C
Wang
S Y
SY
Urbonaviciene
J
J
Jin
D J
DJ
Sondén
B
B
Uhlin
B E
BE
D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics*; D002352:Carrier Proteins; D000242:Cyclic AMP / Q000235:genetics*; D002373:Cyclic AMP Receptor Protein / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D029968:Escherichia coli Proteins; D006158:Guanosine Pentaphosphate / Q000235:genetics*; D018832:Molecular Chaperones; D016296:Mutagenesis; D011401:Promoter Regions, Genetic; D018085:Regulon / Q000235:genetics*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; D018832:Molecular Chaperones; C090104:StpA protein, E coli; D006158:Guanosine Pentaphosphate; D000242:Cyclic AMP; D012321:DNA-Directed RNA Polymerases