The DnaX-binding subunits δ′ and ψ are bound to γ and not τ in the DNA polymerase III holoenzyme
The DnaX-binding subunits δ′ and ψ are bound to γ and not τ in the DNA polymerase III holoenzyme
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DOI：
10.1074/jbc.275.5.3017
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发表时间：
2000-02-04
影响因子：
4.8
通讯作者：
McHenry, CS
中科院分区：
文献类型：
--
作者：
Glover, BP;McHenry, CS
DNA 聚合酶 III 全酶的 DnaX 复合体子组件由 DnaX 蛋白 tau 和 gamma 以及辅助亚基 delta、delta、chi 和 Psi 组成，它们一起在 ATP 依赖性反应中将 β 持续合成因子加载到引发的 DNA 上。 delta' 和 Psi 直接与 DnaX 结合，而 delta 和 chi 分别与 delta' 和 Psi 结合（Onrust, R.、Finkelstein, J.、Naktinis, V.、Turner, J.、Fang, L. 和 O'Donnell, M. (1995) J. Biol. Chem. 270, 13348-13357)。 到目前为止，尚不清楚哪种 DnaX 蛋白，全酶中的 tau 或 gamma 结合辅助亚基 delta、delta' chi 和 Psi。用同型双功能交联剂双（磺基琥珀酰亚胺基）辛二酸酯处理纯化的全酶，产生经蛋白质印迹分析鉴定的共价交联的γ-δ'和γ-Psi复合物。用抗δ'和抗Psi抗体对交联种类进行免疫检测，结果显示没有形成tau-δ'或tau-Psi交联，这表明δ'和Psi亚基仅存在于全酶内的γ上。
The DnaX complex subassembly of the DNA polymerase III holoenzyme is comprised of the DnaX proteins tau and gamma and the auxiliary subunits delta, delta, chi and Psi,which together load the beta processivity factor onto primed DNA in an ATP-dependent reaction. delta' and Psi bind directly to DnaX whereas delta and chi bind to delta' and Psi, respectively (Onrust, R., Finkelstein, J., Naktinis, V., Turner, J., Fang, L., and O'Donnell, M. (1995) J. Biol. Chem. 270, 13348-13357), Until now, it has been unclear which DnaX protein, tau or gamma, in holoenzyme binds the auxiliary subunits delta, delta' chi,and Psi. Treatment of purified holoenzyme with the homobifunctional cross-linker bis(sulfo-succinimidyl)suberate produces covalently cross-linked gamma-delta' and gamma-Psi complexes identified by Western blot analysis. Immunodetection of cross-linked species with anti-delta' and anti-Psi, antibodies revealed that no tau-delta' or tau-Psi cross-links had formed, suggesting that the delta' and Psi subunits reside only on gamma within holoenzyme.