Sanchez Humberto, Carrasco Begoña, Cozar M Castillo, Alonso Juan C
Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Madrid, E-28049 Spain.
Mol Microbiol. 2007 Aug;65(4):920-35. doi: 10.1111/j.1365-2958.2007.05835.x. Epub 2007 Jul 19.
The absence of Bacillus subtilis RecG branch migration translocase causes a defect in cell proliferation, renders cells very sensitive to DNA-damaging agents and increases approximately 150-fold the amount of non-partitioned chromosomes. Inactivation of recF, addA, recH, recV or recU increases both the sensitivity to DNA-damaging agents and the chromosomal segregation defect of recG mutants. Deletion of recS or recN gene partially suppresses cell proliferation, DNA repair and segregation defects of DeltarecG cells, whereas deletion of recA only partially suppresses the segregation defect of DeltarecG cells. Deletion of recG and ripX render cells with very poor viability, extremely sensitive to DNA-damaging agents, and with a drastic segregation defect. After exposure to mitomycin C recG or ripX cells show a drastic defect in chromosome partitioning (approximately 40% of the cells), and this defect is even larger (approximately 60% of the cells) in recG ripX cells. Taken together, these data indicate that: (i) RecG defines a new epistatic group (eta), (ii) RecG is required for proper chromosomal segregation even in the presence of other proteins that process and resolve Holliday junctions, and (iii) different avenues could process Holliday junctions.
枯草芽孢杆菌RecG分支迁移转位酶的缺失会导致细胞增殖缺陷，使细胞对DNA损伤剂非常敏感，并使未分离染色体的数量增加约150倍。recF、addA、recH、recV或recU的失活会增加对DNA损伤剂的敏感性以及recG突变体的染色体分离缺陷。recS或recN基因的缺失部分抑制了ΔrecG细胞的细胞增殖、DNA修复和分离缺陷，而recA的缺失仅部分抑制了ΔrecG细胞的分离缺陷。recG和ripX的缺失使细胞活力非常差，对DNA损伤剂极度敏感，并具有严重的分离缺陷。暴露于丝裂霉素C后，recG或ripX细胞在染色体分配上表现出严重缺陷（约40%的细胞），而在recG ripX细胞中这种缺陷更大（约60%的细胞）。综上所述，这些数据表明：（i）RecG定义了一个新的上位性组（eta），（ii）即使存在其他处理和解析霍利迪连接体的蛋白质，RecG对于正确的染色体分离也是必需的，以及（iii）不同途径可以处理霍利迪连接体。
