Function of RecO Protein in Recombination and Repair in E. coli

摘要大肠杆菌为基因重组研究提供了良好的模型系统。由于易于维持和基因操作，可以对大量重组缺陷突变体进行分离和分析，并随后对基因和各自的基因产物进行鉴定和分析。许多参与同源重组的基因在DNA修复的某些方面也是必需的。至少有三种不同的重组途径，称为RecBCD、RecE和RecF，它们在所需的基因产物方面彼此不同。RecBCD和RecF通路都在野生型细胞中起作用，并且都被认为需要recA基因产物。至少有12个额外的重组基因参与了RecF通路重组的某些方面，但对RecF通路基因产物之间的相互作用以及它们如何在重组中共同起作用知之甚少。所有RecF通路介导的重组都需要recO和recR基因产物。此外，这两种基因产物对于紫外线照射或丝裂霉素C暴露后的DNA修复至关重要。纯化后的RecO蛋白与RecA蛋白具有一定的生化活性，包括d环的形成，RecO在体内可以替代RecA蛋白，这表明两者在功能上是相似的。本研究的目的是进一步研究RecO蛋白在体内的功能，并在体外鉴定和表征与RecO在重组和DNA修复中的功能相关的生化特性。*** DNA代谢的一个方面在分子水平上没有很好地表征是一般重组。重组机制对于产生遗传多样性、在DNA损伤后维持细胞活力以及在减数分裂期间准确分离染色体至关重要。% % %

9412816 Abstract The bacterium E. coli provides a good model system for the study of genetic recombination. The ease with which it is maintained and genetically manipulated has allowed the isolation and analysis of a large number of recombination deficient mutants and the subsequent identification and analysis of the genes and respective gene products. Many of the genes involved in homologous recombination are also required for some aspect of DNA repair. There are at least three distinct recombination pathways termed RecBCD, RecE, and RecF which differ from each other with respect to the gene product(s) required. Both the RecBCD and RecF pathways function in wild type cells, and both are believed to require the recA gene product. At least twelve additional recombination genes are involved in some aspect of RecF pathway recombination, yet very little is known about the interaction between the RecF pathway gene products and how they function together in recombination. All RecF pathway mediated recombination requires the recO and recR gene products. In addition, both gene products are essential for DNA repair following UV irradiation or mitomycin C exposure. Purified RecO protein shares some biochemical activities with RecA protein including D-loop formation, and RecO can substitute for RecA in vivo, suggesting that the two proteins are functionally similar. The goal of this research is to further investigate the function of RecO protein in vivo, and to identify and characterize the biochemical properties associated with RecO in vitro that are relevant to RecO function in recombination and DNA repair. *** One aspect of DNA metabolism that is not well characterized at the molecular level is general recombination. Recombination mechanisms are essential to generate genetic diversity, to maintain cell viability after DNA damage, and to accurately segregate chromosomes during meiosis. %%%