Sengoku Toru, Nureki Osamu, Nakamura Akira, Kobayashi Satoru, Yokoyama Shigeyuki
Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan.
Cell. 2006 Apr 21;125(2):287-300. doi: 10.1016/j.cell.2006.01.054.
DEAD-box RNA helicases, which regulate various processes involving RNA, have two RecA-like domains as a catalytic core to alter higher-order RNA structures. We determined the 2.2 A resolution structure of the core of the Drosophila DEAD-box protein Vasa in complex with a single-stranded RNA and an ATP analog. The ATP analog intensively interacts with both of the domains, thereby bringing them into the closed form, with many interdomain interactions of conserved residues. The bound RNA is sharply bent, avoiding a clash with a conserved alpha helix in the N-terminal domain. This "wedge" helix should disrupt base pairs by bending one of the strands when a duplex is bound. Mutational analyses indicated that the interdomain interactions couple ATP hydrolysis to RNA unwinding, probably through fine positioning of the duplex relative to the wedge helix. This mechanism, which differs from those for canonical translocating helicases, may enable the targeted modulation of intricate RNA structures.
DEAD盒RNA解旋酶可调节涉及RNA的各种过程，它有两个类RecA结构域作为催化核心，以改变高阶RNA结构。我们确定了果蝇DEAD盒蛋白Vasa核心与单链RNA和ATP类似物复合物的2.2埃分辨率结构。ATP类似物与两个结构域都有强烈相互作用，从而使它们形成封闭形式，保守残基之间有许多结构域间相互作用。结合的RNA急剧弯曲，避免与N端结构域中保守的α螺旋发生碰撞。当双链体结合时，这个“楔形”螺旋应该通过弯曲其中一条链来破坏碱基对。突变分析表明，结构域间相互作用可能通过双链体相对于楔形螺旋的精细定位，将ATP水解与RNA解旋耦合起来。这种机制不同于典型的转位解旋酶的机制，可能实现对复杂RNA结构的靶向调节。
