title: The cycling of Escherichia coli DNA polymerase III holoenzyme in replication.
abstract: ATP-activated DNA polymerase III holoenzyme (holoenzyme) forms a stable initiation complex with primed DNA with concomitant hydrolysis of the ATP (Burgers, P. M. J., and Kornberg, A. (1982) J. Biol. Chem. 257, 11468-11478). Upon replication of primed single-stranded circular DNA to a duplex circle with a small gap (RFII), the holoenzyme remains stably bound. Dissociation requires binding by ATP or the generally nonhydrolyzable analog, adenosine 5'-(3-thiotriphosphate). Transfer of holoenzyme to another primed DNA absolutely requires ATP (or dATP) and takes about 2 min at 30 degrees C. The rate of cycling of holoenzyme is only slightly dependent on the concentration of primed DNA. However, the transfer time is reduced to only 2 to 5 s when it is intramolecular, as shown by movement to other primers on the same template chain. A rapid transfer of holoenzyme from a completed chain to another primer on the same template molecule is anticipated from the frequency of initiating nascent chains at the replicating fork of the cellular chromosome (about 1 per s at 37 degrees C) and the low cellular abundance of holoenzyme (about 10 to 20 molecules per cell).
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D011088:DNA Ligases / Q000378:metabolism; D004256:DNA Polymerase I / Q000378:metabolism; D004258:DNA Polymerase III / Q000378:metabolism*; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics
chemical_list: D000255:Adenosine Triphosphate; D004256:DNA Polymerase I; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D011088:DNA Ligases