The Thermus thermophilus DEAD box helicase Hera contains a modified RNA recognition motif domain loosely connected to the helicase core.
The Thermus thermophilus DEAD box helicase Hera contains a modified RNA recognition motif domain loosely connected to the helicase core.
复制标题
DOI：
10.1261/rna.1820009
复制
发表时间：
2009-08
期刊：
影响因子：
4.5
通讯作者：
M. Rudolph;D. Klostermeier
中科院分区：
文献类型：
--
作者：
M. Rudolph;D. Klostermeier
DEAD box 家族解旋酶由解旋酶核心组成，该核心由两个灵活连接的 RecA 样结构域形成。解旋酶活性可以通过核心侧翼的 N 或 C 末端延伸来调节。嗜热栖热菌耐热 RNA 依赖性 ATP 酶 (Hera) 是第一个使用独特二聚化结构域形成二聚体的 DEAD 盒解旋酶。除了二聚化结构域外，Hera 还包含一个 C 端 RNA 结合结构域 (RBD)，仅与异常球菌/栖热菌属中未表征的蛋白质具有序列同源性。 Hera_RBD 的晶体结构揭示了改变的 RNA 识别基序 (RRM) 的折叠，与来自枯草芽孢杆菌的 DEAD 框解旋酶 YxiN 的 RBD 具有有限的结构同源性。与 RRM/RNA 复合物的比较表明，可以推断出 Hera 的 RNA 结合模式与 YxiN 的建议不同，但与 U1A 相似。 RBD 相对于解旋酶核心的方向在 Hera 片段的第二晶体结构中定义，包括 C 端 RecA 结构域、二聚化结构域和 RBD。这些结构允许构建整个赫拉解旋酶二聚体的模型。鉴定出跨越 RecA 样结构域和 RBD 的大 RNA 底物的可能结合表面。
DEAD box family helicases consist of a helicase core that is formed by two flexibly linked RecA-like domains. The helicase activity can be regulated by N- or C-terminal extensions flanking the core. Thermus thermophilus heat resistant RNA-dependent ATPase (Hera) is the first DEAD box helicase that forms a dimer using a unique dimerization domain. In addition to the dimerization domain, Hera contains a C-terminal RNA binding domain (RBD) that shares sequence homology only to uncharacterized proteins of the Deinococcus/Thermus group. The crystal structure of Hera_RBD reveals the fold of an altered RNA recognition motif (RRM) with limited structural homology to the RBD of the DEAD box helicase YxiN from Bacillus subtilis. Comparison with RRM/RNA complexes shows that a RNA binding mode different than that suggested for YxiN, but similar to U1A, can be inferred for Hera. The orientation of the RBD relative to the helicase core was defined in a second crystal structure of a Hera fragment including the C-terminal RecA domain, the dimerization domain, and the RBD. The structures allow construction of a model for the entire Hera helicase dimer. A likely binding surface for large RNA substrates that spans both RecA-like domains and the RBD is identified.