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Regulation of the Escherichia coli heat‐shock response
Author(s) -
Bukau Bernd
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.tb01727.x
Subject(s) - biology , heat shock protein , heat shock , sigma factor , psychological repression , microbiology and biotechnology , escherichia coli , signal transduction , rna polymerase , cold shock domain , protein subunit , stringent response , gene , rna , gene expression , biochemistry
Summary Steady‐state‐ and stress‐induced expression of Escherichia coli heat‐shock genes is regulated at the transcriptional level through controls of concentration and activity of the positive regulator, the heat‐shock promoter‐specific subunit of RNA polymerase, σ; 32 . Central to these controls are functions of the DnaK, DnaJ, GrpE heat‐shock proteins as negative modulators that mediate degradation as well as repression of activity and, in some conditions, of synthesis of σ 32 . DnaJ has a key role in modulation since it binds σ 32 and, jointly with DnaK and GrpE, represses its activity. Furthermore, DnaJ is capable of binding heat‐damaged proteins, targeting DnaK and GrpE to these substrates, and thereby mediating DnaK‐, DnaJ‐, GrpE‐dependent repair. It is proposed that one important signal transduction pathway that converts stress to a heat‐shock response relies on the sequestering of DnaJ through binding to damaged proteins which derepresses and stabilizes σ 32 . Damage repair ameliorates the inducing signal and frees DnaJ, DnaK, GrpE to shut off the heat‐shock response.