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首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >Structures of monomeric, dimeric and trimeric PCNA: PCNA-ring assembly and opening.
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Structures of monomeric, dimeric and trimeric PCNA: PCNA-ring assembly and opening.

机译：单体的结构、二聚的和三聚物的PCNA: PCNA-ring组装开放。

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摘要

DNA sliding clamps form an oligomeric ring encircling DNA and serve as a moving platform for DNA-processing proteins. The opening and closing of a sliding-clamp ring is essential to load the clamp onto DNA in order to perform its functions. The molecular details of how clamp rings open and enclose DNA are still not clear. Three PCNA homologues have been found in Sulfolobus solfataricus which form a heterotrimer. Taking advantage of their hetero-oligomeric nature, the structures of the PCNAs in monomeric PCNA3, dimeric PCNA1-PCNA2 and trimeric PCNA1-PCNA2-PCNA3 forms were determined at resolutions of 2.6-1.9 A. The distinct oligomeric structures represent different stages in ring formation, which were verified in solution by ultracentrifugation analysis. The heterodimer opens in a V-shape of 130 degrees , while the heterotrimers form a ring with a 120 degrees rotation between monomers. The association of a rigid PCNA3 monomer with an opened PCNA1-PCNA2 heterodimer closes the ring and introduces a springtension in the PCNA1-PCNA2 interface, thus bending the nine-stranded intermolecular beta-sheet to fit the 120 degrees rotation. The release of the spring tension as PCNA3 dissociates from the ring may facilitate ring opening. The structural features in different assemblies present a molecular model for clamp ring assembly and opening.
机译：DNA滑动夹形成低聚物的戒指环绕DNA和作为一个移动平台dna的加工蛋白质方面取得。的滑动压板环加载至关重要夹到DNA来执行其功能。的分子细节如何夹环和开放附上DNA仍不清楚。同系物在硫化叶菌被发现solfataricus heterotrimer构成。利用他们的hetero-oligomeric自然,建筑单体的pcna的PCNA3,二聚的PCNA1-PCNA2和三聚物的PCNA1-PCNA2-PCNA3形式确定2.6 - -1.9的决议。在环结构代表不同的阶段在溶液中形成,验证超速离心法分析。打开130度的v字形,而用120度heterotrimers形成一个环单体之间旋转。刚性PCNA3单体PCNA1-PCNA2打开异质二聚体关闭环和介绍了springtension PCNA1-PCNA2界面,因此弯曲的nine-stranded分子间β褶板以适应120度旋转。PCNA3释放弹簧张力分离环可能促进环开放。装配夹的分子模型环装配和开放。

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