A new DNA polymerase activity was identified and purified to near homogeneity from extracts of mitotic and meiotic cells of the yeast Saccharomyces cerevisiae. This activity increased at least 5-fold during meiosis, and it was shown to be associated with a 68-kDa polypeptide as determined by SDS-polyacrylamide gel electrophoresis. This new DNA polymerase did not have any detectable 3′ → 5′ exonuclease activity and preferred small gapped DNA as a template-primer. The activity was inhibited by dideoxyribonucleoside 5′-triphosphates and N-ethylmaleimide but not by concentrations of aphidicolin which completely inhibit either DNA polymerases I (α), II (ε), or III (δ). Since no polypeptide(s) in the extensively purified DNA polymerase fractions cross-reacted with antibodies raised against yeast DNA polymerases I, II, and III, we called this enzyme DNA polymerase IV. The DNA polymerase IV activity increased at least 10-fold in a yeast strain overexpressing the gene product predicted from the YCR14C open-reading frame (identified on S. cerevisiae chromosome III and provisionally called POLX), while no activity was detected in a strain where POLX was deleted. These results strongly suggest that DNA polymerase IV is encoded by the POLX gene and is a probable homolog of mammalian DNA polymerase β.
|Titolo:||Purification and characterization of a new DNA polymerase from budding yeast Saccharomyces cerevisiae. A probable homolog of mammalian DNA polymerase beta|
|Parole Chiave:||Animals; DNA Polymerase I; Sequence Homology, Nucleic Acid; Electrophoresis, Polyacrylamide Gel; Humans; Saccharomyces cerevisiae Proteins; DNA Polymerase beta; Saccharomyces cerevisiae; Potassium Chloride; Base Sequence; Kinetics; DNA Primers; Escherichia coli; Molecular Sequence Data; Substrate Specificity; Magnesium; DNA-Directed DNA Polymerase|
|Settore Scientifico Disciplinare:||Settore BIO/11 - Biologia Molecolare|
|Data di pubblicazione:||25-dic-1993|
|Appare nelle tipologie:||01 - Articolo su periodico|