Specific recognition of RNA/DNA hybrid and enhancement of human RNase H1 activity by HBD
Specific recognition of RNA/DNA hybrid and enhancement of human RNase H1 activity by HBD
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DOI：
10.1038/emboj.2008.44
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发表时间：
2008-04-09
期刊：
影响因子：
11.4
通讯作者：
Yang, Wei
中科院分区：
文献类型：
--
作者：
Nowotny, Marcin;Cerritelli, Susana M.;Yang, Wei
人RNaseH1含有一个被称为dsRHbd的N-末端结构域，用于结合dsRNA和RNA/DNA杂交体。我们发现dsRHbd优先与RNA/DNA杂交物结合超过25倍，并将其更名为杂交结合域(HBD)。HBD与12bp的RNA/DNA杂化产物的晶体结构表明，RNA链被蛋白质环识别，与2‘-OH基团形成氢键。DNA界面具有高度的特异性，含有与磷酸基团相互作用的极性残基，以及对结合脱氧核糖具有选择性的芳香族斑块。HBD相对于非序列特异性dsDNA和dsRNA结合域是独特的，因为它不使用α-螺旋的正偶极进行核酸结合。对具有缺陷HBD的全长酶的表征表明，该结构域显著增强了RNaseH1的比活性和加工性。与催化结构域连接的小底物结合结构域可能在其他核酸酶中也有类似的活性增强。
Human RNase H1 contains an N-terminal domain known as dsRHbd for binding both dsRNA and RNA/DNA hybrid. We find that dsRHbd binds preferentially to RNA/DNA hybrids by over 25-fold and rename it as hybrid binding domain (HBD). The crystal structure of HBD complexed with a 12 bp RNA/DNA hybrid reveals that the RNA strand is recognized by a protein loop, which forms hydrogen bonds with the 2'-OH groups. The DNA interface is highly specific and contains polar residues that interact with the phosphate groups and an aromatic patch that appears selective for binding deoxyriboses. HBD is unique relative to non-sequence-specific dsDNA- and dsRNA-binding domains because it does not use positive dipoles of alpha-helices for nucleic acid binding. Characterization of full-length enzymes with defective HBDs indicates that this domain dramatically enhances both the specific activity and processivity of RNase H1. Similar activity enhancement by small substrate-binding domains linked to the catalytic domain likely occurs in other nucleic acid enzymes.