title: dnaG gene product, a rifampicin-resistant RNA polymerase, initiates the conversion of a single-stranded coliphage DNA to its duplex replicative form.
abstract: The protein responsible for the initiation of conversion of single-stranded phage G4 DNA to the duplex replicative form has been purified approximately 3000-fold and identified with Escherichia coli dnaG gene product. The protein is a rifampicin-resistant RNA polymerase of approximately 64,000 daltons. It catalyzes the incorporation of the four ribonucleoside triphosphates into an oligoribonucleotide, using as template the single-stranded DNA coated with the DNA unwinding protein of E. coli. An RNA transcript of a unique region of the chromosome can serve as a primer by covalent extension by DNA polymerase III holoenzyme to form a nearly full-length linear complementary strand. A similar role for the dnaG protein in the initiation of nascent (Okazaki) fragments in replication of the host chromosome is discussed.
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism; D002852:Chromatography, Ion Exchange; D003090:Coliphages / Q000187:drug effects / Q000378:metabolism*; D004254:DNA Nucleotidyltransferases / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects*; D004267:DNA Viruses / Q000187:drug effects / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004352:Drug Resistance, Microbial; D004355:Drug Stability; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism*; D005796:Genes; D005816:Genetic Complementation Test; D006358:Hot Temperature; D007700:Kinetics; D009154:Mutation; D012293:Rifampin / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004254:DNA Nucleotidyltransferases; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin