Bugreev Dmitry V, Huang Fei, Mazina Olga M, Pezza Roberto J, Voloshin Oleg N, Camerini-Otero R Daniel, Mazin Alexander V
1] Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102-1192, USA [2].
Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102-1192, USA.
Nat Commun. 2014 Jun 19;5:4198. doi: 10.1038/ncomms5198.
The HOP2-MND1 heterodimer is required for progression of homologous recombination in eukaryotes. In vitro, HOP2-MND1 stimulates the DNA strand exchange activities of RAD51 and DMC1. We demonstrate that HOP2-MND1 induces changes in the conformation of RAD51 that profoundly alter the basic properties of RAD51. HOP2-MND1 enhances the interaction of RAD51 with nucleotide cofactors and modifies its DNA-binding specificity in a manner that stimulates DNA strand exchange. It enables RAD51 DNA strand exchange in the absence of divalent metal ions required for ATP binding and offsets the effect of the K133A mutation that disrupts ATP binding. During nucleoprotein formation HOP2-MND1 helps to load RAD51 on ssDNA restricting its dsDNA-binding and during the homology search it promotes dsDNA binding removing the inhibitory effect of ssDNA. The magnitude of the changes induced in RAD51 defines HOP2-MND1 as a 'molecular trigger' of RAD51 DNA strand exchange.
HOP2-MND1异二聚体是真核生物中同源重组过程所必需的。在体外，HOP2-MND1可刺激RAD51和DMC1的DNA链交换活性。我们证明，HOP2-MND1可诱导RAD51构象发生变化，从而深刻改变RAD51的基本特性。HOP2-MND1增强了RAD51与核苷酸辅因子的相互作用，并以刺激DNA链交换的方式改变其DNA结合特异性。它能使RAD51在缺乏ATP结合所需二价金属离子的情况下进行DNA链交换，并抵消破坏ATP结合的K133A突变的影响。在核蛋白形成过程中，HOP2-MND1有助于将RAD51加载到单链DNA上，限制其与双链DNA的结合，而在同源性搜索过程中，它促进双链DNA结合，消除单链DNA的抑制作用。RAD51中诱导变化的程度将HOP2-MND1定义为RAD51 DNA链交换的“分子触发器”。
