Three-dimensional structure of ribonuclease H from E. coli
Three-dimensional structure of ribonuclease H from E. coli
复制标题
大肠杆菌核糖核酸酶 H 的三维结构
作者：
K. Katayanagi;M. Miyagawa;M. Matsushima;M. Ishikawa;S. Kanaya;M. Ikehara;T. Matsuzaki;K. Morikawa
利用X射线晶体学，在1.8 nm分辨率下测定了大肠杆菌核糖核酸酶H的三维结构。发现该酶属于α + β类结构，由两个不同的结构域组成。该结构暗示了与DNA-RNA杂合体相互作用的可能区域。活性所必需的Mg 2+结合位点位于四个酸性氨基酸簇附近-一个谷氨酸和三个天冬氨酸残基。这些残基在逆转录病毒和逆转录病毒样实体的RNA酶H和逆转录酶序列的同源性比对中是完全保守的1，2。Mg 2+结合位点周围β链的结构基序与DNase I3-6中的结构基序相似。
THE three-dimensional structure of RNase H from Escherichia coli was determined at 1.8 Å resolution by X-ray crystallography. The enzyme was found to belong to the α + β class of structures, consisting of two distinct domains. The structure implies a possible region interacting with a DNA–RNA hybrid. The Mg2+-binding site essential for activity is located near a cluster of four acidic amino acids— one glutamic and three aspartic acid residues. These residues are completely conserved in the homology alignment of sequences of RNase H and reverse transcriptases from retro viruses and retrovirus-like entities1,2. The structural motif of β strands around the Mg2+-binding site has similarities to that in DNase I3–6.