Korolev S, Hsieh J, Gauss G H, Lohman T M, Waksman G
Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Cell. 1997 Aug 22;90(4):635-47. doi: 10.1016/s0092-8674(00)80525-5.
Crystal structures of binary and ternary complexes of the E. coli Rep helicase bound to single-stranded (ss) DNA or ssDNA and ADP were determined to a resolution of 3.0 A and 3.2 A, respectively. The asymmetric unit in the crystals contains two Rep monomers differing from each other by a large reorientation of one of the domains, corresponding to a swiveling of 130 degrees about a hinge region. Such domain movements are sufficiently large to suggest that these may be coupled to translocation of the Rep dimer along DNA. The ssDNA binding site involves the helicase motifs Ia, III, and V, whereas the ADP binding site involves helicase motifs I and IV. Residues in motifs II and VI may function to transduce the allosteric effects of nucleotides on DNA binding. These structures represent the first view of a DNA helicase bound to DNA.
大肠杆菌Rep解旋酶与单链（ss）DNA或ssDNA及ADP形成的二元和三元复合物的晶体结构分别解析到了3.0埃和3.2埃的分辨率。晶体中的不对称单元包含两个Rep单体，其中一个结构域发生了大幅重新定向，导致二者不同，这对应于围绕一个铰链区旋转130度。这种结构域运动足够大，表明它们可能与Rep二聚体沿DNA的易位相关。ssDNA结合位点涉及解旋酶基序Ia、III和V，而ADP结合位点涉及解旋酶基序I和IV。基序II和VI中的残基可能起到转导核苷酸对DNA结合的变构效应的作用。这些结构代表了DNA解旋酶与DNA结合的首次景象。
