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A lowered concentration of cAMP receptor protein caused by glucose is an important determinant for catabolite repression in Escherichia coli
Author(s) -
Ishizuka Hitoshi,
Hanamura Akemi,
Kunimura Tadashi,
Aiba Hiroji
Publication year - 1993
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1993.tb01960.x
Subject(s) - catabolite repression , biology , escherichia coli , camp receptor protein , psychological repression , biochemistry , microbiology and biotechnology , gene , mutant , gene expression , promoter
Summary A decreased intracellular concentration of cAMP is insufficient to account for catabolite repression in Escherichia coli. We show that glucose lowers the amount of cAMP receptor protein (CRP) in cells. A correlation exists between CRP and β‐galactosidase levels in cells growing under various conditions. Exogenous cAMP completely eliminates catabolite repression in CRP‐overproducing cells, while it does not fully reverse the effect of glucose on β‐galactosidase expression in wild‐type cells. When the CRP concentration is reduced by manipulating the crp gene, β‐galactosidase expression decreases in proportion to the concentration of CRP. These findings indicate that the lowered concentration of CRP caused by glucose is one of the major factors for catabolite repression. We propose that glucose causes catabolite repression by lowering the intracellular levels of both CRP and cAMP.