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复制体组合揭示了前进和落后链复制中的不对称函数的基础

A Yuzhakov¹, J Turner, M O'Donnell

¹Microbiology Department, Howard Hughes Medical Institute, Cornell University Medical College, New York 10021, USA.

|September 20, 1996

概括

大肠杆菌中的两个DNA聚合酶III聚合酶在DNA复制方面具有相等的能力. 不对称的功能来自于酶相互作用,而不是聚合酶差异,允许灵活的复合体组装.

科学领域:

分子生物学分子生物学
生物化学生物化学
遗传学是一个遗传学.

背景情况:

由于反平行DNA链,DNA复制需要精确协调领先和滞后链的合成.
众所周知,大肠杆菌DNA聚合酶III全酶,主要复制酶含有两个聚合酶子单元.
目前的理解认为,这两种聚合酶在复制不同DNA链中的作用是不对称的.

研究的目的:

调查大肠杆菌DNA聚合酶III全酶中的两个聚合酶的功能对称性或不对称性.
为了确定两个聚合酶是否具有同等的能力来复制领先和滞后的DNA链.
阐明其他复制体组件,如酶在强加功能不对称性中的作用.

主要方法:

生物化学测试以评估聚合酶活性和基质特异性.
在实验室复制研究中,使用大肠杆菌复制体的净化成分.
突变分析或蛋白质相互作用研究,以探测酶对聚合酶功能的影响.

主要成果:

该研究发现,这两种DNA聚合酶III聚合酶均表现出相当的生物化学性质.
两种聚合酶都被证明能够合成更复杂的滞后链.
不对称的复制是由与环酶的物理相互作用所强加的,该环环绕着滞后链.

结论:

大肠杆菌DNA聚合酶III全酶中的两个聚合酶具有对称的功能能力.
观察到的不对称复制是一种由酶-聚合酶相互作用决定的新兴性质,而不是固有的聚合酶差异.
这种对称性允许全酶以任何方向聚集到复制体中,增强复制的灵活性.

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