title: A DNA polymerase from Ustilago maydis. 1. Purification and properties of the polymerase activity.
abstract: A DNA polymerase from Ustilago maydis has been purified to apparent homogeneity. The native enzyme possesses a subunit structure consisting of 50000 and 55000-dalton monomers. The apparent sedimentation coefficient of the polymerase activity in the absence of salt is 8.4 S (Mr=180000-200000), that in its presence (0.6 M NaCl or 0.12 M KCl) being 6.3 S (Mr=80000-100000). Low concentrations of EDTA also converted the 8.4-S to a 6.3-S form, whereas magnesium ions catalysed the reverse association. The enzyme has an absolute requirement for both a DNA or RNA template and a DNA primer. For homopolymer templates the primer requirement was satisified by a short complementary oligodeoxynucleotide, but oligoribonucleotides were extremely inefficient primers. With the template-primer poly(dA) X (dT)12, the enzyme added an average of 50 dTMP nucleotides on to each primer molecule, whereas with poly(rA) X (dT)12, this figure was 300. The enzyme also possesses an associated deoxyribonuclease activity. No other DNA polymerase activity was detected in cell-free extracts of U. maydis.
mesh_terms: D001487:Basidiomycota / Q000201:enzymology*; D002413:Cations, Divalent; D002414:Cations, Monovalent; D004254:DNA Nucleotidyltransferases / Q000302:isolation & purification* / Q000378:metabolism; D004261:DNA Replication; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D013698:Templates, Genetic; D014588:Ustilago / Q000201:enzymology*
chemical_list: D002413:Cations, Divalent; D002414:Cations, Monovalent; D046911:Macromolecular Substances; D004254:DNA Nucleotidyltransferases