Structure of a mutant form of proliferating cell nuclear antigen that blocks translesion DNA synthesis.
Structure of a mutant form of proliferating cell nuclear antigen that blocks translesion DNA synthesis.
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DOI：
10.1021/bi8017762
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发表时间：
2008-12-16
期刊：
影响因子：
2.9
通讯作者：
Washington, M. Todd
中科院分区：
文献类型：
--
作者：
Freudenthal, Bret D.;Ramaswamy, S.;Hingorani, Manju M.;Washington, M. Todd
增殖细胞核抗原(增殖细胞核抗原)是一种同源三聚体蛋白，在DNA复制过程中起到滑动夹的作用。在酵母的遗传学研究中，已经发现了几种突变形式的增殖细胞核抗原，它们可以阻止跨病变DNA的合成。其中一种突变蛋白(由rev6-1等位基因编码)是位于增殖细胞核抗原亚单位界面的178位甘氨酸到丝氨酸的替代。为了更好地了解这种替代是如何干扰跨病变合成的，我们测定了G178S增殖细胞核抗原突变蛋白的X射线晶体结构。这种取代对发生取代的结构域的结构几乎没有影响。相反，在邻近的亚基中观察到了显著的局部结构变化。突变型结构和野生型结构之间最显著的区别是在一个单一的扩展环(包括氨基酸残基105-110)中，我们称之为环J。在突变的蛋白质结构中，环J采用了非常不同的构象，其中蛋白质骨架的原子从它们在野生型结构中的位置移动了多达6.5？为了更好地了解这种结构变化的功能后果，我们检测了这种突变蛋白通过DNA聚合酶ETA(Pollη)刺激核苷酸掺入的能力。稳态动力学研究表明，当野生型增殖细胞核抗原刺激相对碱基位置的PolDNA的掺入时，突变的增殖细胞核抗原蛋白实际上抑制了与η损伤相反的掺入。这些结果表明，环J在增殖细胞核抗原中的位置在促进跨病变合成方面起着至关重要的作用。
Proliferating cell nuclear antigen (PCNA) is a homotrimeric protein that functions as a sliding clamp during DNA replication. Several mutant forms of PCNA that block translesion DNA synthesis have been identified in genetic studies in yeast. One such mutant protein (encoded by the rev6-1 allele) is a glycine to serine substitution at residue 178, located at the subunit interface of PCNA. To better understand how this substitution interferes with translesion synthesis, we have determined the X-ray crystal structure of the G178S PCNA mutant protein. This substitution has little effect on the structure of the domain in which the substitution occurs. Instead, significant, local structural changes are observed in the adjacent subunit. The most notable difference between mutant and wild-type structures is in a single, extended loop (comprising amino acid residues 105-110), which we call loop J. In the mutant protein structure, loop J adopts a very different conformation in which the atoms of the protein backbone have moved by as much as 6.5 Å from their positions in the wild-type structure. To better understand the functional consequences of this structural change, we have examined the ability of this mutant protein to stimulate nucleotide incorporation by DNA polymerase eta (pol η). Steady state kinetic studies show that while wild-type PCNA stimulates incorporation by pol η opposite an abasic site, the mutant PCNA protein actually inhibits incorporation opposite this DNA lesion. These results show that the position of loop J in PCNA plays an essential role in facilitating translesion synthesis.
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影响因子：
4.8
作者：
Garg, P;Stith, CM;Burgers, PMJ
通讯作者：
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影响因子：
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作者：
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DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
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作者：
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通讯作者：
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作者：
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通讯作者：
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作者：
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