Cra-mediated regulation of Escherichia coli adenylate cyclase.
In Escherichia coli, expression of certain genes and operons, including the fructose operon, is controlled by Cra, the pleiotropic catabolite repressor/activator protein formerly known as FruR. In this study we have demonstrated that cra mutant strains synthesize 10-fold less cAMP than isogenic wild-type strains, specifically when grown in fructose-containing minimal media. The glucose-specific IIA protein (IIAglc) of the phosphotransferase system, which activates adenylate cyclase when phosphorylated, is largely dephosphorylated in cra but not wild-type strains growing under these conditions. Dephosphorylation of IIAglc in cra strains apparently results from enhanced fructose operon transcription and fructose uptake. These conclusions were supported by showing that fructose-grown cra strains possess 2.5-fold higher fructose-1-phosphate kinase activity than fructose-grown wild-type strains. Moreover, artificially increasing fructose operon expression in cells transporting fructose dramatically decreased the activity of adenylate cyclase. The results establish that Cra indirectly regulates the activity of adenylate cyclase by controlling the expression of the fructose operon in cells growing with fructose as the sole carbon source.
Crasnier-Mednansky
Martine
M
University of California at San Diego, Department of Biology, La Jolla, CA 92093-0116, USA.
Park
Maxwell C
MC
University of California at San Diego, Department of Biology, La Jolla, CA 92093-0116, USA.
Studley
William K
WK
University of California at San Diego, Department of Biology, La Jolla, CA 92093-0116, USA.
Saier
Milton H
MH
University of California at San Diego, Department of Biology, La Jolla, CA 92093-0116, USA.
D000262:Adenylyl Cyclases / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D009154:Mutation; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D056968:Lac Repressors
D000262:Adenylyl Cyclases; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; C489416:FruR protein, E coli; C068837:FruR protein, Bacteria; D056968:Lac Repressors