Dionne Isabelle, Nookala Ravi K, Jackson Stephen P, Doherty Aidan J, Bell Stephen D
Medical Research Council Cancer Cell Unit, Hutchison MRC Research Centre, Hills Road, Cambridge CB2 2XZ, United Kingdom.
Mol Cell. 2003 Jan;11(1):275-82. doi: 10.1016/s1097-2765(02)00824-9.
The sliding clamp, PCNA, of the archaeon Sulfolobus solfataricus P2 is a heterotrimer of three distinct subunits (PCNA1, 2, and 3) that assembles in a defined manner. The PCNA heterotrimer, but not individual subunits, stimulates the activities of the DNA polymerase, DNA ligase I, and the flap endonuclease (FEN1) of S. solfataricus. Distinct PCNA subunits contact DNA polymerase, DNA ligase, or FEN1, imposing a defined architecture at the lagging strand fork and suggesting the existence of a preformed scanning complex at the fork. This provides a mechanism to tightly couple DNA synthesis and Okazaki fragment maturation. Additionally, unique subunit-specific interactions between components of the clamp loader, RFC, suggest a model for clamp loading of PCNA.
嗜热栖热菌P2的滑动夹PCNA是由三个不同亚基（PCNA1、2和3）组成的异源三聚体，它们以特定方式组装。PCNA异源三聚体而非单个亚基可刺激嗜热栖热菌的DNA聚合酶、DNA连接酶I和瓣状核酸内切酶（FEN1）的活性。不同的PCNA亚基与DNA聚合酶、DNA连接酶或FEN1接触，在滞后链叉处形成特定结构，这表明叉处存在预先形成的扫描复合物。这提供了一种紧密耦合DNA合成和冈崎片段成熟的机制。此外，钳位装载器RFC各组分之间独特的亚基特异性相互作用提示了PCNA钳位装载的模型。
