Identification of a beta-like DNA polymerase activity in bovine heart mitochondria.
A new DNA polymerase activity, distinct from DNA polymerase gamma, has been identified in bovine heart mitochondria. First detected among proteins isolated in a complex with mitochondrial DNA, the DNA polymerase activity has been partially purified 47,000-fold. Enzyme activity separates from DNA polymerase gamma on several chromatographic columns and appears to copurify with a 38 +/- 2-kDa polypeptide. Unlike DNA polymerase gamma, this enzyme is relatively resistant to inhibition by N-ethylmaleimide and dideoxynucleotides, has moderately low monovalent and high divalent cation requirements, and possesses 20-fold-higher apparent K(m) values for deoxynucleotides. The enzyme polymerizes deoxynucleotides onto a primed template DNA in a relatively nonprocessive fashion and lacks a detectable 3' to 5' exonuclease activity. Many of these characteristics resemble a beta-like mitochondrial DNA polymerase previously identified in, and considered unique to, trypanosomes. We propose that the bovine and trypanosomal enzymes are related and represent a new class of ubiquitous mitochondrial DNA polymerases.
Nielsen-Preiss
S M
SM
Department of Pathology, School of Medicine, Health Sciences Center, University of Colorado, 4200 East Ninth Avenue, Denver, Colorado 80262, USA.
Low
R L
RL
D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D002414:Cations, Monovalent / Q000494:pharmacology; D002417:Cattle; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D019951:DNA Polymerase beta / Q000302:isolation & purification / Q000378:metabolism*; D000074002:DNA Polymerase gamma; D004272:DNA, Mitochondrial / Q000302:isolation & purification / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000302:isolation & purification; D004795:Enzyme Stability; D005033:Ethylmaleimide / Q000494:pharmacology; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology*; D008970:Molecular Weight; D013379:Substrate Specificity; D013698:Templates, Genetic
D002413:Cations, Divalent; D002414:Cations, Monovalent; D004272:DNA, Mitochondrial; D019951:DNA Polymerase beta; D000074002:DNA Polymerase gamma; D004259:DNA-Directed DNA Polymerase; D005033:Ethylmaleimide