Sheridan Sean D, Yu Xiong, Roth Robyn, Heuser John E, Sehorn Michael G, Sung Patrick, Egelman Edward H, Bishop Douglas K
Committee on Genetics, University of Chicago, Chicago, IL 60637, USA.
Nucleic Acids Res. 2008 Jul;36(12):4057-66. doi: 10.1093/nar/gkn352. Epub 2008 Jun 4.
The eukaryotic RecA homologs Rad51 and Dmc1 are essential for strand exchange between homologous chromosomes during meiosis. All members of the RecA family of recombinases polymerize on DNA to form helical nucleoprotein filaments, which is the active form of the protein. Here we compare the filament structures of the Rad51 and Dmc1 proteins from both human and budding yeast. Previous studies of Dmc1 filaments suggested that they might be structurally distinct from filaments of other members of the RecA family, including Rad51. The data presented here indicate that Rad51 and Dmc1 filaments are essentially identical with respect to several structural parameters, including persistence length, helical pitch, filament diameter, DNA base pairs per helical turn and helical handedness. These data, together with previous studies demonstrating similar in vitro recombinase activity for Dmc1 and Rad51, support the view that differences in the meiotic function of Rad51 and Dmc1 are more likely to result from the influence of distinct sets of accessory proteins than from intrinsic differences in filament structure.
真核生物中RecA的同源物Rad51和Dmc1对于减数分裂期间同源染色体之间的链交换至关重要。重组酶RecA家族的所有成员都会在DNA上聚合，形成螺旋状核蛋白丝，这是该蛋白质的活性形式。在此，我们比较了来自人类和芽殖酵母的Rad51和Dmc1蛋白的丝结构。先前对Dmc1丝的研究表明，它们在结构上可能与RecA家族的其他成员（包括Rad51）的丝不同。此处给出的数据表明，Rad51和Dmc1丝在几个结构参数方面基本相同，包括持久长度、螺旋间距、丝直径、每螺旋圈的DNA碱基对以及螺旋方向。这些数据，连同先前证明Dmc1和Rad51具有相似体外重组酶活性的研究，支持了这样一种观点，即Rad51和Dmc1在减数分裂功能上的差异更可能是由不同的辅助蛋白集的影响导致的，而不是丝结构的内在差异。
