Division of Infectious Diseases, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
Nucleic Acids Res. 2013 Feb 1;41(4):2284-95. doi: 10.1093/nar/gks1298. Epub 2013 Jan 7.
Mycobacteria have two genetically distinct pathways for the homology-directed repair of DNA double-strand breaks: homologous recombination (HR) and single-strand annealing (SSA). HR is abolished by deletion of RecA and reduced in the absence of the AdnAB helicase/nuclease. By contrast, SSA is RecA-independent and requires RecBCD. Here we examine the function of RecO in mycobacterial DNA recombination and repair. Loss of RecO elicits hypersensitivity to DNA damaging agents similar to that caused by deletion of RecA. We show that RecO participates in RecA-dependent HR in a pathway parallel to the AdnAB pathway. We also find that RecO plays a role in the RecA-independent SSA pathway. The mycobacterial RecO protein displays a zinc-dependent DNA binding activity in vitro and accelerates the annealing of SSB-coated single-stranded DNA. These findings establish a role for RecO in two pathways of mycobacterial DNA double-strand break repair and suggest an in vivo function for the DNA annealing activity of RecO proteins, thereby underscoring their similarity to eukaryal Rad52.
分枝杆菌有两种基因上不同的同源定向修复 DNA 双链断裂的途径：同源重组 (HR) 和单链退火 (SSA)。RecA 的缺失会使 HR 失活，而 AdnAB 解旋酶/核酸酶的缺失则会降低 HR 的效率。相比之下，SSA 与 RecA 无关，需要 RecBCD。在这里，我们研究了 RecO 在分枝杆菌 DNA 重组和修复中的功能。RecO 的缺失会引起对 DNA 损伤剂的敏感性增加，类似于 RecA 缺失引起的敏感性增加。我们表明 RecO 参与了依赖 RecA 的 HR，其途径与 AdnAB 途径平行。我们还发现 RecO 在依赖 RecA 的 SSA 途径中发挥作用。分枝杆菌 RecO 蛋白在体外显示出锌依赖性 DNA 结合活性，并加速 SSB 包裹的单链 DNA 的退火。这些发现确立了 RecO 在分枝杆菌 DNA 双链断裂修复的两种途径中的作用，并表明 RecO 蛋白的 DNA 退火活性在体内具有功能，从而强调了它们与真核 Rad52 的相似性。
