title: Mechanism of dnaB protein action. IV. General priming of DNA replication by dnaB protein and primase compared with RNA polymerase.
abstract: The general priming system of dnaB protein and primase (Arai, K., and Kornberg, A. (1979) Proc. Natl. Acad. Sci. U. S. A. 76, 4308-4312) when compared with priming by RNA polymerase shows a number of striking differences. The general priming system is initiated primarily at single-stranded region(S), being active only on single-stranded DNAs (phages and homopolymers) and inhibited by single-stranded DNA binding protein (SSB). Transcripts are only 10 to 60 residues long. By contrast, RNA priming by RNA polymerase is initiated at base-paired regions that are not destabilized by SSB (Geider, K., Beck, E., and Schaller, H. (1978) Proc. Natl. Acad. Sci. U. S. A. 76, 645-649) and transcripts on DNA not coated with SSB are generally longer. In general priming, ATP (or GTP) has three functions: (i) an allosteric effect on dnaB protein in which the nonhydrolyzed analogs adenosine-5'-O-(3'-thiotriphosphate) (or guanosine-5'-O-(3'-thiotriphosphate) can substitute, (ii) initiation of primer synthesis which can incorporate deoxy-, as well as ribonucleotides, and (iii) elongation of the primer, in which the beta, gamma-imido analog can replace ATP (or GTP). An allosteric effect of ATP on RNA polymerase has not been demonstrated, nor has the facile synthesis of hybrid transcripts of ribo- and deoxyribonucleotides.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001482:Base Composition; D004247:DNA / Q000378:metabolism; D004258:DNA Polymerase III / Q000378:metabolism*; D019915:DNA Primase; D004261:DNA Replication; D004279:DNA, Viral; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D007700:Kinetics; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011119:Polynucleotides; D012316:RNA Nucleotidyltransferases / Q000378:metabolism*; D013698:Templates, Genetic
chemical_list: D001426:Bacterial Proteins; D004279:DNA, Viral; D011119:Polynucleotides; D004247:DNA; D019915:DNA Primase; D012316:RNA Nucleotidyltransferases; D012321:DNA-Directed RNA Polymerases; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D010744:Phosphoric Monoester Hydrolases