Structural mechanisms of DNA binding and unwinding in bacterial RecQ helicases
Structural mechanisms of DNA binding and unwinding in bacterial RecQ helicases
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DOI：
10.1073/pnas.1416746112
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发表时间：
2015-04-07
影响因子：
11.1
通讯作者：
Keck, James L.
中科院分区：
文献类型：
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作者：
Manthei, Kelly A.;Hill, Morgan C.;Keck, James L.
RecQ解旋酶解旋作为许多细胞过程的关键组分的显著不同的DNA结构。RecQ酶如何在一个统一的机制中适应不同的底物，将ATP水解与DNA解旋偶联，这是未知的。在这里，坂崎克罗伊氏菌RecQ催化核心结构域与具有3'单链延伸的双链体DNA结合的X射线晶体结构鉴定了两种DNA依赖性构象重排：翼状螺旋结构域以类似90度的枢轴旋转以接近双链体DNA，并且保守的富含芳香族的环被重塑以结合ssDNA。这些变化与RecQ ATP酶活性位点的重组相一致，RecQ ATP酶活性位点定位ATP水解的催化残基。复合物的形成也诱导DNA的紧密弯曲并使双链体的一部分熔化。这种弯曲，加上易位，可以为RecQ提供解旋双链体和其他DNA结构的机制。
RecQ helicases unwind remarkably diverse DNA structures as key components of many cellular processes. How RecQ enzymes accommodate different substrates in a unified mechanism that couples ATP hydrolysis to DNA unwinding is unknown. Here, the X-ray crystal structure of the Cronobacter sakazakii RecQ catalytic core domain bound to duplex DNA with a 3' single-stranded extension identifies two DNA-dependent conformational rearrangements: a winged-helix domain pivots similar to 90 degrees to close onto duplex DNA, and a conserved aromatic-rich loop is remodeled to bind ssDNA. These changes coincide with a restructuring of the RecQ ATPase active site that positions catalytic residues for ATP hydrolysis. Complex formation also induces a tight bend in the DNA and melts a portion of the duplex. This bending, coupled with translocation, could provide RecQ with a mechanism for unwinding duplex and other DNA structures.