PCNA structure and function: Insights from structures of PCNA complexes and post-translationally modi fied PCNA

Abstract

Proliferating cell nuclear antigen (PCNA), the eukaryotic DNA sliding clamp, forms a ring-shaped homo-trimer that encircles double-stranded DNA. This protein is best known for its ability to confer high processivity to replicative DNA polymerases. However, it does far more than this, because it forms a mobile platform on the DNA that recruits many of the proteins involved in DNA replication, repair, and recombination to replication forks. X-ray crystal structures of PCNA bound to PCNA-binding proteins have provided insights into how PCNA recognizes its binding partners and recruits them to replication forks. More recently, X-ray crystal structures of ubiquitin-modi fied and SUMO-modi fied PCNA have provided insights into how these post-translational modi fications alter the speci ficity of PCNA for some of its binding partners. This article focuses on the insights gained from structural studies of PCNA complexes and post-translationally modi fied PCNA.