Role of the core DNA polymerase III subunits at the replication fork. Alpha is the only subunit required for processive replication.
The DNA polymerase III holoenzyme is composed of 10 subunits. The core of the polymerase contains the catalytic polymerase subunit, alpha, the proofreading 3'-->5' exonuclease, epsilon, and a subunit of unknown function, theta. The availability of the holoenzyme subunits in purified form has allowed us to investigate their roles at the replication fork. We show here that of the three subunits in the core polymerase, only alpha is required to form processive replication forks that move at high rates and that exhibit coupled leading- and lagging-strand synthesis in vitro. Taken together with previous data this suggests that the primary determinant of replication fork processivity is the interaction between another holoenzyme subunit, tau, and the replication fork helicase, DnaB.
Marians
K J
KJ
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Hiasa
H
H
Kim
D R
DR
McHenry
C S
CS
D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology; D004247:DNA / Q000096:biosynthesis; D004265:DNA Helicases / Q000737:chemistry; D004258:DNA Polymerase III / Q000737:chemistry / Q000502:physiology*; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism; D053488:DnaB Helicases; D009690:Nucleic Acid Conformation; D013698:Templates, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C103076:DnaX protein, Bacteria; C022262:Okazaki fragments; D004247:DNA; C074904:DNA polymerase III, alpha subunit; D004258:DNA Polymerase III; D004265:DNA Helicases; D053488:DnaB Helicases