Kamtekar Satwik, Ho Roger S, Cocco Melanie J, Li Weikai, Wenwieser Sandra V C T, Boocock Martin R, Grindley Nigel D F, Steitz Thomas A
Departments of Molecular Biophysics, and Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA.
Proc Natl Acad Sci U S A. 2006 Jul 11;103(28):10642-7. doi: 10.1073/pnas.0604062103. Epub 2006 Jun 28.
The structures of two mutants of the site-specific recombinase, gammadelta resolvase, that form activated tetramers have been determined. One, at 3.5-A resolution, forms a synaptic intermediate of resolvase that is covalently linked to two cleaved DNAs, whereas the other is of an unliganded structure determined at 2.1-A resolution. Comparisons of the four known tetrameric resolvase structures show that the subunits interact through the formation of a common core of four helices. The N-terminal halves of these helices superimpose well on each other, whereas the orientations of their C termini are more variable. The catalytic domains of resolvase in the unliganded structure are arranged asymmetrically, demonstrating that their positions can move substantially while preserving the four-helix core that forms the tetramer. These results suggest that the precleavage synaptic tetramer of gammadelta resolvase, whose structure is not known, may be formed by a similar four-helix core, but differ in the relative orientations of its catalytic and DNA-binding domains.
已确定位点特异性重组酶γδ 解离酶的两种形成活化四聚体的突变体结构。一种在3.5埃分辨率下形成解离酶的突触中间体，该中间体与两条切割后的DNA共价连接，而另一种是在2.1埃分辨率下确定的未结合配体的结构。对四种已知的四聚体解离酶结构的比较表明，亚基通过形成由四个螺旋组成的共同核心相互作用。这些螺旋的N端半部彼此很好地重叠，而它们C端的方向则更具变化性。未结合配体结构中的解离酶催化结构域不对称排列，表明它们的位置在保留形成四聚体的四螺旋核心的同时可以大幅移动。这些结果表明，结构未知的γδ 解离酶切割前突触四聚体可能由类似的四螺旋核心形成，但其催化结构域和DNA结合结构域的相对方向不同。
