Warbrick E, Lane D P, Glover D M, Cox L S
Department Anatomy and Physiology, University of Dundee, UK.
Oncogene. 1997 May 15;14(19):2313-21. doi: 10.1038/sj.onc.1201072.
Following genomic damage, the cessation of DNA replication is co-ordinated with onset of DNA repair; this co-ordination is essential to avoid mutation and genomic instability. To investigate these phenomena, we have analysed proteins that interact with PCNA, which is required for both DNA replication and repair. One such protein is p21Cip1, which inhibits DNA replication through its interaction with PCNA, while allowing repair to continue. We have identified an interaction between PCNA and the structure specific nuclease, Fen1, which is involved in DNA replication. Deletion analysis suggests that p21Cip1 and Fen1 bind to the same region of PCNA. Within Fen1 and its homologues a small region (10 amino acids) is sufficient for PCNA binding, which contains an 8 amino acid conserved PCNA-binding motif. This motif shares critical residues with the PCNA-binding region of p21Cip1. A PCNA binding peptide from p21Cip1 competes with Fen1 peptides for binding to PCNA, disrupts the Fen1-PCNA complex in replicating cell extracts, and concomitantly inhibits DNA synthesis. Competition between homologous regions of Fen1 and p21Cip1 for binding to the same site on PCNA may provide a mechanism to co-ordinate the functions of PCNA in DNA replication and repair.
在基因组损伤后，DNA复制的停止与DNA修复的开始相互协调；这种协调对于避免突变和基因组不稳定至关重要。为了研究这些现象，我们分析了与PCNA相互作用的蛋白质，PCNA是DNA复制和修复所必需的。其中一种蛋白质是p21Cip1，它通过与PCNA相互作用抑制DNA复制，同时允许修复继续进行。我们已经确定了PCNA与结构特异性核酸酶Fen1之间的相互作用，Fen1参与DNA复制。缺失分析表明p21Cip1和Fen1结合到PCNA的同一区域。在Fen1及其同源物中，一个小区域（10个氨基酸）足以与PCNA结合，该区域包含一个8个氨基酸的保守PCNA结合基序。这个基序与p21Cip1的PCNA结合区域共享关键残基。来自p21Cip1的PCNA结合肽与Fen1肽竞争结合PCNA，破坏复制细胞提取物中的Fen1-PCNA复合物，并同时抑制DNA合成。Fen1和p21Cip1的同源区域竞争结合PCNA上的同一位点，这可能提供了一种协调PCNA在DNA复制和修复中功能的机制。
