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PMID:2681183

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Citation

Tsuchihashi, Z and Kornberg, A (1989) ATP interactions of the tau and gamma subunits of DNA polymerase III holoenzyme of Escherichia coli. J. Biol. Chem. 264:17790-5

Abstract

The tau and gamma subunits of the DNA polymerase III holoenzyme of Escherichia coli were each isolated in large quantities as oligomers from overproducing cells in which their genes (dnaZ and X) were under the control of a T7 phage promoter. The 52-kDa gamma subunit (encoded by the dnaZ sequence) contains three-forths of the N-terminal residues of the 71-kDa tau subunit (encoded by the dnaX sequence). Both gamma and tau share a binding site for ATP (or dATP). A DNA-dependent ATPase activity (Lee, S.H., and Walker, J.R. (1987) Proc. Natl. Acad. Sci. U. S. A. 84, 2713-2717) exhibited only by the tau subunit, presumably requires a DNA-binding site in the C-terminal domain lacking in the gamma subunit. Among ATPases dependent on single-stranded DNA, the tau activity is remarkable in the failure of homopolymers (e.g. poly(dA) or poly(dT)) to replace natural DNAs. The presumed need for certain secondary structures may reflect a feature of template binding in the crucial contribution that tau makes to the high processivity of polymerase III holoenzyme. Limited tryptic digestion of tau generates a fragment that resembles gamma in: (i) size, (ii) binding of ATP without ATPase activity, and (iii) a level of complementing holoenzyme activity in extracts of dnaZ-mutant cells that is higher than that of tau.

Links

PubMed

Keywords

Adenosine Triphosphate/metabolism; Amino Acid Sequence; Bacterial Proteins; Base Sequence; DNA Polymerase III/genetics; DNA Polymerase III/isolation & purification; DNA Polymerase III/metabolism; DNA-Directed DNA Polymerase/metabolism; Escherichia coli/enzymology; Escherichia coli/genetics; Genes, Bacterial; Macromolecular Substances; Molecular Sequence Data; Peptide Mapping; Plasmids; Promoter Regions, Genetic; Templates, Genetic

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ECOLI:DPO3X

enables

GO:0016887: ATPase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

See also

References

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