Subramanya H S, Arciszewska L K, Baker R A, Bird L E, Sherratt D J, Wigley D B
Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
EMBO J. 1997 Sep 1;16(17):5178-87. doi: 10.1093/emboj/16.17.5178.
The structure of the site-specific recombinase, XerD, that functions in circular chromosome separation, has been solved at 2.5 A resolution and reveals that the protein comprises two domains. The C-terminal domain contains two conserved sequence motifs that are located in similar positions in the structures of XerD, lambda and HP1 integrases. However, the extreme C-terminal regions of the three proteins, containing the active site tyrosine, are very different. In XerD, the arrangement of active site residues supports a cis cleavage mechanism. Biochemical evidence for DNA bending is encompassed in a model that accommodates extensive biochemical and genetic data, and in which the DNA is wrapped around an alpha-helix in a manner similar to that observed for CAP complexed with DNA.
在环状染色体分离过程中发挥作用的位点特异性重组酶XerD的结构已在2.5埃分辨率下解析出来，结果显示该蛋白质由两个结构域组成。C端结构域包含两个保守序列基序，它们在XerD、λ和HP1整合酶的结构中处于相似位置。然而，这三种蛋白质包含活性位点酪氨酸的极端C端区域却大不相同。在XerD中，活性位点残基的排列支持顺式切割机制。DNA弯曲的生化证据包含在一个模型中，该模型整合了大量生化和遗传数据，其中DNA以类似于与DNA复合的CAP所观察到的方式缠绕在一个α螺旋上。
