Marians K J, Hiasa H, Kim D R, McHenry C S
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
J Biol Chem. 1998 Jan 23;273(4):2452-7. doi: 10.1074/jbc.273.4.2452.
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.
DNA聚合酶III全酶由10个亚基组成。聚合酶的核心包含催化性聚合酶亚基α、校对3'→5'核酸外切酶ε以及一个功能未知的亚基θ。纯化形式的全酶亚基的可得性使我们能够研究它们在复制叉处的作用。我们在此表明，在核心聚合酶的三个亚基中，只有α是形成能高速移动并在体外表现出前导链和滞后链合成偶联的持续合成复制叉所必需的。结合先前的数据，这表明复制叉持续合成能力的主要决定因素是另一个全酶亚基τ与复制叉解旋酶DnaB之间的相互作用。
