title: Characterization of DNA polymerase induced by bacteriophage T5 with DNA containing single strand breaks.
abstract: DNA polymerase induced by bacteriophage T5 was purified and characterized using mainly circular duplex DNA of bacteriophage PM2 with single strand breaks formed by DNase I action. A purification procedure is described which has consistently yielded DNA polymerase preparations with only one detectable protein band after polyacrylamide gel electrophoresis of either native protein in Tris-glyase preparations utilized both denatured DNA and nicked DNA as primer-templates, although at 37 degrees the activity with denatured DNA was much greater. Polymerase activities with both kinds of primer-templates were shown to be associated with one phage-induced protein. DNA synthesis with nicked DNA as primer-template increased with increasing numbers of single strand breaks. Essentially all such breaks were repairable by ligase. Alkaline sucrose gradient centrifugation showed that synthesis occurred with the strand which had a single strand break as a primer yielding DNA longer than one phage DNA unit length. Newly synthesized DNA was covalently linked to the primer strand. Thus the synthesis very likely occurred by strand displacement; this is supported by electron micrographs shown in the Appendix.
mesh_terms: D003090:Coliphages / Q000201:enzymology*; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D003851:Deoxyribonucleases; D004926:Escherichia coli / Q000201:enzymology*; D008970:Molecular Weight; D011118:Polynucleotide Ligases / Q000378:metabolism; D013698:Templates, Genetic
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004254:DNA Nucleotidyltransferases; D003851:Deoxyribonucleases; D011118:Polynucleotide Ligases