Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA polymerase III holoenzyme has been purified from Escherichia coli HMS-83, using, as an assay, the conversion of coliphage G4 single-stranded DNA to the duplex replicative form. The holoenzyme consists of at least four different subunits: alpha, beta, gamma, and delta of 140,000, 40,000, 52,000, and 32,000 daltons, respectively. The alpha subunit is DNA polymerase III, the dnaE gene product. The holoenzyme has been resolved by phosphocellulose chromatography into an alpha - gamma - delta complex and a subunit beta (copolymerase III*); neither possesses detectable activity in the G4 system but together reconstitute holoenzyme-like activity. The alpha - gamma - delta complex has been further resolved to yield a gamma - delta complex which reconstitutes alpha - gamma - delta activity when added to DNA polymerase III. The gamma - delta complex contains a product of the dnaZ gene and has been purified from a strain which contains a ColE1-dnaZ hybrid plasmid.
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PMID:DNA polymerase III holoenzyme of Escherichia coli. Purification and resolution into subunits. 33 May 31

DNA polymerase III, the core of the DNA polymerase III holoenzyme, has been purified 28,000-fold to 97% homogeneity from Escherichia coli HMS-83. The enzyme contains subunits: alpha, epsilon, and theta of 140,000, 25,000, and 10,000 daltons, respectively. The alpha subunit has been previously shown to be a component of both DNA polymerase III and the more complex DNA polymerase III holoenzyme (Livingston, D.M., Hinkle, D., and Richardson, C. (1975) J. Biol. Chem. 250, 461-469; McHenry, C., and Kornberg, A. (1977) J. Biol. Chem. 252, 6478-6484). It is demonstrated here that the epsilon and theta subunits are also subunits of the DNA polymerase III holoenzyme. Thus, the DNA polymerase III holoenzyme contains at least six different subunits. Our preparation has both the 3' leads to 5' and 5' leads to 3' exonuclease activities previously assigned to DNA polymerase III (Livingston, D., and Richardson, C. (1975) J. Biol. Chem. 250, 470-478).
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PMID:DNA polymerase III of Escherichia coli. Purification and identification of subunits. 36 75

The beta subunit of the DNA polymerase III holoenzyme has been purified 10,000-fold to homogeneity from Escherichia coli HMS-83. The native and denatured molecular weights of beta are 72,000 and 37,000, as determined by equilibrium sedimentation. Thus, beta appears to exist as a dimer when in a state free of other holoenzyme components. This conclusion is supported by the native molecular weight calculated from the sedimentation coefficient (5.0 S) and the Stokes radius (32.5 A) and subunit molecular weights determined from denaturing polyacrylamide gel electrophoresis. An antibody directed specifically against the beta subunit has been prepared and found to block the DNA polymerase III holoenzyme-catalyzed reaction, but not reactions which require only the core DNA polymerase III. Furthermore, this antibody blocks the initiation, but not the elongation reaction catalyzed by the DNA polymerase III holoenzyme. Thus, beta may only be required for formation of the initiation complex between polymerase components and a primed template. Immunoprecipitation studies demonstrate that the beta subunit forms a complex with other holoenzyme components in solution, in the absence of DNA.
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PMID:Purification and characterization of the beta subunit of the DNA polymerase III holoenzyme of Escherichia coli. 677 24