Ayora Silvia, Carrasco Begoña, Doncel-Perez Ernesto, Lurz Rudi, Alonso Juan C
Department of Microbial Biotechnology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Proc Natl Acad Sci U S A. 2004 Jan 13;101(2):452-7. doi: 10.1073/pnas.2533829100. Epub 2003 Dec 30.
Bacillus subtilis RecU protein is involved in homologous recombination, DNA repair, and chromosome segregation. Purified RecU binds preferentially to three- and four-strand junctions when compared to single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) ( approximately 10- and approximately 40-fold lower efficiency, respectively). RecU cleaves mobile four-way junctions but fails to cleave a linear dsDNA with a putative cognate site, a finding consistent with a similar genetic defect observed for genes classified within the epsilon epistatic group (namely ruvA, recD, and recU). In the presence of Mg(2+), RecU also anneals a circular ssDNA and a homologous linear dsDNA with a ssDNA tail and a linear ssDNA and a homologous supercoiled dsDNA substrate. These results suggest that RecU, which cleaves recombination intermediates with high specificity, might also help in their assembly.
枯草芽孢杆菌RecU蛋白参与同源重组、DNA修复和染色体分离。与单链DNA（ssDNA）和双链DNA（dsDNA）相比，纯化的RecU优先结合三链和四链连接（效率分别低约10倍和约40倍）。RecU可切割动态四向连接，但无法切割具有假定同源位点的线性dsDNA，这一发现与ε上位组内分类的基因（即ruvA、recD和recU）观察到的类似遗传缺陷一致。在Mg(2+)存在的情况下，RecU还可使环状ssDNA与具有ssDNA尾巴的同源线性dsDNA以及线性ssDNA与同源超螺旋dsDNA底物退火。这些结果表明，具有高特异性切割重组中间体功能的RecU可能也有助于它们的组装。
