Sickmier E Allen, Kreuzer Kenneth N, White Stephen W
Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
Structure. 2004 Apr;12(4):583-92. doi: 10.1016/j.str.2004.02.016.
In bacteriophage T4, the WXY system repairs DNA damage by a process that involves homologous recombination. This system comprises three proteins, the RecA-like recombination protein UvsX, a recombination mediator protein UvsY, and a helicase UvsW. Here we report the 2.0 A resolution crystal structure of the N-terminal two domains of the UvsW helicase (UvsWNF; residues 1-282). The structure reveals a typical helicase RecA-like domain linked to a small N-terminal alpha/beta domain that likely binds the nucleic acid substrate. The missing C-terminal portion of UvsW almost certainly corresponds to the second RecA-like domain typically found in monomeric helicases. The putative substrate binding domain is unique within the known helicase structures, and it resembles the novel "double-wing" DNA binding domain from the phage T4 MotA transcription factor that mediates the expression of T4 middle genes. The functional implications of this homology for the role of UvsW in T4 DNA metabolism are discussed.
在噬菌体T4中，WXY系统通过涉及同源重组的过程修复DNA损伤。该系统由三种蛋白质组成，即RecA样重组蛋白UvsX、重组介导蛋白UvsY和一种解旋酶UvsW。在此，我们报道了解旋酶UvsW N端两个结构域（UvsWNF；第1至282位氨基酸残基）分辨率为2.0埃的晶体结构。该结构揭示了一个典型的解旋酶RecA样结构域与一个可能结合核酸底物的小的N端α/β结构域相连。UvsW缺失的C端部分几乎肯定对应于单体解旋酶中通常存在的第二个RecA样结构域。推测的底物结合结构域在已知的解旋酶结构中是独特的，它类似于噬菌体T4 MotA转录因子中新型的“双翼”DNA结合结构域，该转录因子介导T4中期基因的表达。本文讨论了这种同源性对UvsW在T4 DNA代谢中作用的功能意义。
