Levels of epsilon, an essential replication subunit of Escherichia coli DNA polymerase III, are controlled by heat shock proteins

UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology



Document Type


Medical Subject Headings

Bacterial Proteins; DNA Polymerase III; DNA Replication; Escherichia coli; *Gene Expression Regulation, Bacterial; Heat-Shock Proteins; Lac Operon; Macromolecular Substances; Protein Conformation; Recombinant Proteins; Ribonuclease H; Transcription, Genetic; beta-Galactosidase


In Escherichia coli, epsilon, the proofreading subunit of DNA polymerase III, is encoded by dnaQ. A random search for mutants that affect the expression of dnaQ revealed that mutations in the genes encoding the heat shock proteins (HSPs) DnaK, DnaJ, and GrpE result in dramatic decreases in the cellular levels of epsilon. dnaQ is arranged in an overlapping divergent transcriptional unit with rnhA, which encodes RNase H1, and mutations in the same HSPs also reduced the apparent levels of RNase H1. The HSPs had only small effects on transcriptional fusions to these genes; thus, it is likely that they operate primarily at the protein level. Since survival and mutagenesis after DNA damage are affected by epsilon and RNase H1, HSPs may have a broad influence on various aspects of DNA replication and repair.

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Citation: J Bacteriol. 1992 Dec;174(23):7509-16.

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