Che Shiyou, Chen Yujing, Liang Yakun, Zhang Qionglin, Bartlam Mark
College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, People's Republic of China.
Acta Crystallogr F Struct Biol Commun. 2018 Apr 1;74(Pt 4):222-230. doi: 10.1107/S2053230X18003503. Epub 2018 Mar 22.
DNA damage is usually lethal to all organisms. Homologous recombination plays an important role in the DNA damage-repair process in prokaryotic organisms. Two pathways are responsible for homologous recombination in Pseudomonas aeruginosa: the RecBCD pathway and the RecFOR pathway. RecR is an important regulator in the RecFOR homologous recombination pathway in P. aeruginosa. It forms complexes with RecF and RecO that can facilitate the loading of RecA onto ssDNA in the RecFOR pathway. Here, the crystal structure of RecR from P. aeruginosa PAO1 (PaRecR) is reported. PaRecR crystallizes in space group P622, with two monomers per asymmetric unit. Analytical ultracentrifugation data show that PaRecR forms a stable dimer, but can exist as a tetramer in solution. The crystal structure shows that dimeric PaRecR forms a ring-like tetramer architecture via crystal symmetry. The presence of a ligand in the Walker B motif of one RecR subunit suggests a putative nucleotide-binding site.
DNA损伤通常对所有生物体都是致命的。同源重组在原核生物的DNA损伤修复过程中起着重要作用。铜绿假单胞菌中的同源重组由两条途径负责：RecBCD途径和RecFOR途径。RecR是铜绿假单胞菌RecFOR同源重组途径中的一个重要调节因子。它与RecF和RecO形成复合物，可促进RecA在RecFOR途径中加载到单链DNA上。在此，报道了铜绿假单胞菌PAO1（PaRecR）的RecR晶体结构。PaRecR以P622空间群结晶，每个不对称单元有两个单体。分析型超速离心数据表明，PaRecR形成稳定的二聚体，但在溶液中可以以四聚体形式存在。晶体结构表明，二聚体PaRecR通过晶体对称性形成环状四聚体结构。一个RecR亚基的沃克B基序中存在配体，提示存在一个推定的核苷酸结合位点。
