title: Isolation and characterization of two mutant forms of T4 polynucleotide kinase.
abstract: The purification of polynucleotide kinase from Escherichia coli infected by two different mutants in the T4 polynucleotide kinase (pseT) gene is described. The pseT 1 enzyme has virtually no 3' specific phosphatase activity and normal polynucleotide kinase activity. The pseT 47 enzyme has very little phosphatase activity and no kinase activity. However, enzyme isolated from a pseT 1, pseT 47 mixed infection appears to contain heterodimers with considerably more phosphatase activity. Thus, the pseT 47 mutation partially inactivates the phosphatase and totally inactivates the kinase. A study of the action of polynucleotide kinase on plasmid DNAs nicked to give a 3'-phosphate and a 5'-hydroxyl indicates that although the enzyme can catalyze both the removal of the 3'-phosphate and the insertion of a 5'-phosphate, there is no evidence for a concerted reaction involving both activities on the same polypeptide chain.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D009154:Mutation; D010770:Phosphotransferases / Q000302:isolation & purification*; D011116:Polynucleotide 5'-Hydroxyl-Kinase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D013604:T-Phages / Q000201:enzymology* / Q000235:genetics
chemical_list: D000596:Amino Acids; D010770:Phosphotransferases; D011116:Polynucleotide 5'-Hydroxyl-Kinase