Shiba T, Iwasaki H, Nakata A, Shinagawa H
Department of Experimental Chemotherapy, Osaka University, Japan.
Proc Natl Acad Sci U S A. 1991 Oct 1;88(19):8445-9. doi: 10.1073/pnas.88.19.8445.
The ruv operon is induced by treatments that damage DNA and is regulated by the LexA repressor. It encodes two proteins, RuvA and RuvB, that are involved in DNA repair, recombination in RecE and RecF pathways, and mutagenesis. RuvB protein was previously purified and has ATP-binding activity and weak ATPase activity. To study the biochemical properties of RuvA and its interaction with RuvB, we purified RuvA protein to near homogeneity from an over-producing strain. RuvA bound more efficiently to single-stranded DNA than to double-stranded DNA. RuvA bound to DNA greatly enhanced the ATPase activity of RuvB; the enhancing effect of various forms of DNA was in the order of supercoiled DNA greater than single-stranded DNA greater than linear double-stranded DNA. UV irradiation further enhanced the ATPase stimulatory effect of supercoiled DNA dose dependently. The RuvA-RuvB complex has an activity that renatures the cruciform structure in supercoiled DNA. From these experiments and previous work, we infer that the RuvA-RuvB complex may promote branch migration in recombination and may correct irregular structures in DNA, such as cruciforms and hairpins, to facilitate DNA repair using ATP as the energy source.
ruv操纵子可被损伤DNA的处理诱导，并受LexA阻遏物调控。它编码两种蛋白质，RuvA和RuvB，它们参与DNA修复、RecE和RecF途径中的重组以及诱变。RuvB蛋白先前已被纯化，具有ATP结合活性和较弱的ATP酶活性。为了研究RuvA的生化特性及其与RuvB的相互作用，我们从一个过量表达菌株中纯化了近乎纯一的RuvA蛋白。RuvA与单链DNA的结合比与双链DNA的结合更有效。RuvA与DNA的结合极大地增强了RuvB的ATP酶活性；各种形式的DNA的增强作用顺序为超螺旋DNA大于单链DNA大于线性双链DNA。紫外线照射剂量依赖性地进一步增强了超螺旋DNA的ATP酶刺激作用。RuvA-RuvB复合物具有使超螺旋DNA中的十字形结构复性的活性。从这些实验和先前的工作中，我们推断RuvA-RuvB复合物可能促进重组中的分支迁移，并可能纠正DNA中的不规则结构，如十字形和发夹结构，以利用ATP作为能量来源促进DNA修复。
