McHenry C S
J Biol Chem. 1982 Mar 10;257(5):2657-63.
DNA polymerase III', a new form of DNA polymerase III, has been purified 15,000-fold to 90% homogeneity from an Escherichia coli K12 strain. DNA polymerase III's is a subassembly of four subunits of the DNA polymerase III holoenzyme; it has functional and physical properties intermediate between the core DNA polymerase III and holoenzyme. Polyacrylamide gel electrophoresis performed under denaturing conditions indicates DNA polymerase III' to be a complex of the alpha, epsilon, and theta subunits of DNA polymerase III and a newly assigned subunit of the DNA polymerase III holoenzyme, tau (Mr = 83,000). Both gel filtration and phosphocellulose chromatography separate DNA polymerase III from DNA polymerase III'. All enzyme forms can utilize a duplex template containing short gaps. DNA polymerase III', like the DNA polymerase III holoenzyme, can synthesize DNA on a long single-stranded template in the presence of 5 mM spermidine; DNA polymerase III cannot. Alone, DNA polymerase III' is inert in the G4 natural replicative system in which the DNA polymerase III holoenzyme is active. Molecular weight and subunit stoichiometry determinations suggest that DNA polymerase III' contains two units of core DNA polymerase III and two tau subunits.
DNA聚合酶III'是DNA聚合酶III的一种新形式，已从大肠杆菌K12菌株中纯化了15000倍，达到90%的纯度。DNA聚合酶III'是DNA聚合酶III全酶四个亚基的一个亚组件；它具有介于核心DNA聚合酶III和全酶之间的功能和物理特性。在变性条件下进行的聚丙烯酰胺凝胶电泳表明，DNA聚合酶III'是DNA聚合酶III的α、ε和θ亚基与DNA聚合酶III全酶新确定的一个亚基tau（分子量=83000）的复合物。凝胶过滤和磷酸纤维素色谱法都能将DNA聚合酶III与DNA聚合酶III'分离。所有酶形式都能利用含有短缺口的双链模板。与DNA聚合酶III全酶一样，DNA聚合酶III'在存在5 mM亚精胺的情况下能在长单链模板上合成DNA；而DNA聚合酶III则不能。单独存在时，DNA聚合酶III'在DNA聚合酶III全酶具有活性的G4天然复制系统中是无活性的。分子量和亚基化学计量测定表明，DNA聚合酶III'含有两个核心DNA聚合酶III单元和两个tau亚基。
