Crystal structures of tyrosyl-tRNA synthetases from Archaea
Crystal structures of tyrosyl-tRNA synthetases from Archaea
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DOI：
10.1016/j.jmb.2005.10.073
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发表时间：
2006-01-20
影响因子：
5.6
通讯作者：
Yokoyama, S
中科院分区：
文献类型：
--
作者：
Kuratani, M;Sakai, H;Yokoyama, S
酪氨酸-tRNA合成酶（TyrRS）在两步反应中催化tRNA（Try）的酪氨酸化。TyrRS具有“HIGH”和“KMSKS”基序，它们在酪氨酸和ATR形成酪氨酸腺苷酸的过程中起着至关重要的作用。在这里，我们分别在1.8埃和2.2埃分辨率下测定了l -酪氨酸结合形式下的fulgidarchaeobus和horikoshii焦球菌TyrRS的晶体结构，以及在2.2埃分辨率下测定了无底物形式下的pernix Aeropyrum TyrRS的晶体结构。KMSKS基序的构象在三个tyrrs中是不同的。在A. pernix TyrRS中，KMSKS环构象对应于atp结合的“封闭”形式。相比之下，P. horikoshii TyrRS的KMSKS环形成了一个新的3（10）螺旋，似乎对应于“半封闭”形式。这种构象扩大了酪氨酸结合袋的入口，促进了酪氨酸腺苷酸形成后焦磷酸离子的释放，可能参与了最初的tRNA结合。讨论了酪氨酸激活反应中KMSKS基序的变化。我们认为，在某些古细菌物种中，KMSKS基序前面的插入序列增强了TyrRS与其同源tRNA的结合亲和力。此外，参与tRNA结合的非脯氨酸顺式肽键在古细菌TyrRSs中是保守的。(c) 2005 Elsevier Ltd版权所有。
Tyrosyl-tRNA synthetase (TyrRS) catalyzes the tyrosylation of tRNA(Try) in a two-step reaction. TyrRS has the '' HIGH '' and '' KMSKS '' motifs, which play essential roles in the formation of the tyrosyl-adenylate from tyrosine and ATR. Here, we determined the crystal structures of Archaeoglobus fulgidus and Pyrococcus horikoshii TyrRSs in the L-tyrosine-bound form at 1.8 angstrom and 2.2 angstrom resolutions, respectively, and that of Aeropyrum pernix TyrRS in the substrate-free form at 2.2 angstrom. The conformation of the KMSKS motif differs among the three TyrRSs. In the A. pernix TyrRS, the KMSKS loop conformation corresponds to the ATP-bound '' closed '' form. In contrast, the KMSKS loop of the P. horikoshii TyrRS forms a novel 3(10) helix, which appears to correspond to the '' semi-closed '' form. This conformation enlarges the entrance to the tyrosine-binding pocket, which facilitates the pyrophosphate ion release after the tyrosyl-adenylate formation, and probably is involved in the initial tRNA binding. The KMSSS loop of the A. fulgidus TyrRS is somewhat farther from the active site and is stabilized changes of the KMSKS motif during the tyrosine activation reaction are discussed. We suggest that the insertion sequence just before the KMSKS motif, which exists in some archaeal species, enhances the binding affinity of the TyrRS for its cognate tRNA. In addition, a non-proline cis peptide bond, which is involved in the tRNA binding, is conserved among the archaeal TyrRSs. (c) 2005 Elsevier Ltd. All rights reserved.