Timmins Joanna, Leiros Ingar, McSweeney Sean
Macromolecular Crystallography Group, European Synchrotron Radiation Facility, Grenoble-CEDEX 9, France.
EMBO J. 2007 Jul 11;26(13):3260-71. doi: 10.1038/sj.emboj.7601760. Epub 2007 Jun 21.
The crystal structure of the complex formed between Deinococcus radiodurans RecR and RecO (drRecOR) has been determined. In accordance with previous biochemical characterisation, the drRecOR complex displays a RecR:RecO molecular ratio of 2:1. The biologically relevant drRecOR entity consists of a heterohexamer in the form of two drRecO molecules positioned on either side of the tetrameric ring of drRecR, with their OB (oligonucleotide/oligosaccharide-binding) domains pointing towards the interior of the ring. Mutagenesis studies validated the protein-protein interactions observed in the crystal structure and allowed mapping of the residues in the drRecOR complex required for DNA binding. Furthermore, the preferred DNA substrate of drRecOR was identified as being 3'-overhanging DNA, as encountered at ssDNA-dsDNA junctions. Together these results suggest a possible mechanism for drRecOR recognition of stalled replication forks.
已确定嗜放射栖热菌RecR与RecO(drRecOR)形成的复合物的晶体结构。与先前的生化特性一致,drRecOR复合物显示出RecR:RecO分子比为2:1。具有生物学相关性的drRecOR实体由一个异源六聚体组成,其形式为两个drRecO分子位于drRecR四聚体环的两侧,其OB(寡核苷酸/寡糖结合)结构域指向环的内部。诱变研究验证了晶体结构中观察到的蛋白质-蛋白质相互作用,并允许绘制drRecOR复合物中DNA结合所需的残基图谱。此外,drRecOR的首选DNA底物被确定为3'突出端DNA,如在单链DNA-双链DNA连接处所遇到的那样。这些结果共同表明了drRecOR识别停滞复制叉的一种可能机制。