Department of Biology, The University of Iowa, Iowa City, IA 52242, USA.
Department of Biochemistry, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
Nucleic Acids Res. 2021 Feb 26;49(4):2005-2026. doi: 10.1093/nar/gkaa1293.
Replication Protein A (RPA) is a critical complex that acts in replication and promotes homologous recombination by allowing recombinase recruitment to processed DSB ends. Most organisms possess three RPA subunits (RPA1, RPA2, RPA3) that form a trimeric complex critical for viability. The Caenorhabditis elegans genome encodes RPA-1, RPA-2 and an RPA-2 paralog RPA-4. In our analysis, we determined that RPA-2 is critical for germline replication and normal repair of meiotic DSBs. Interestingly, RPA-1 but not RPA-2 is essential for somatic replication, in contrast to other organisms that require both subunits. Six different hetero- and homodimeric complexes containing permutations of RPA-1, RPA-2 and RPA-4 can be detected in whole animal extracts. Our in vivo studies indicate that RPA-1/4 dimer is less abundant in the nucleus and its formation is inhibited by RPA-2. While RPA-4 does not participate in replication or recombination, we find that RPA-4 inhibits RAD-51 filament formation and promotes apoptosis of a subset of damaged nuclei. Altogether these findings point to sub-functionalization and antagonistic roles of RPA complexes in C. elegans.
复制蛋白 A（RPA）是一种关键的复合物，通过允许重组酶募集到加工过的双链断裂末端，在复制和促进同源重组中发挥作用。大多数生物体都具有三种 RPA 亚基（RPA1、RPA2、RPA3），它们形成一个对生存至关重要的三聚体复合物。秀丽隐杆线虫的基因组编码 RPA-1、RPA-2 和 RPA-2 平行物 RPA-4。在我们的分析中，我们确定 RPA-2 对生殖系复制和减数分裂 DSB 的正常修复至关重要。有趣的是，与其他需要两个亚基的生物体相反，RPA-1 而不是 RPA-2 对体细胞复制是必需的。在整个动物提取物中可以检测到六种不同的含有 RPA-1、RPA-2 和 RPA-4 排列的异源和同源二聚体复合物。我们的体内研究表明，RPA-1/4 二聚体在核内的丰度较低，其形成受到 RPA-2 的抑制。虽然 RPA-4 不参与复制或重组，但我们发现 RPA-4 抑制 RAD-51 丝的形成并促进一部分受损核的凋亡。总的来说，这些发现指出了 RPA 复合物在秀丽隐杆线虫中的亚功能化和拮抗作用。
