Active-site monovalent cations revealed in a 1.55-Å-resolution hammerhead ribozyme structure.
Active-site monovalent cations revealed in a 1.55-Å-resolution hammerhead ribozyme structure.
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DOI：
10.1016/j.jmb.2013.05.017
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发表时间：
2013-10-23
影响因子：
5.6
通讯作者：
Scott, William G.
中科院分区：
文献类型：
--
作者：
Anderson, Michael;Schultz, Eric P.;Martick, Monika;Scott, William G.
我们在允许详细观察核酶活性位点中 Na+ 离子结合的条件下获得了源自曼氏血吸虫的锤头核酶的 1.55 Å 晶体结构。至少观察到两个这样的Na+离子。第一个 Na+ 离子以与之前观察到的二价阳离子相同的方式与 G10.1 的 N7 和相邻的 A9 磷酸盐结合。第二个 Na+ 离子与 G12（锤头裂解反应中的一般碱基）的 Hoogsteen 面结合，从而可能消散核苷酸碱基的催化活性烯醇化物形式的负电荷。一个潜在但更模糊的第三个位点以与之前预测一致的方式桥接 A9 和裂变磷酸盐。已观察到锤头核酶在高浓度单价阳离子（包括 Na+）存在下具有活性，但单价阳离子在锤头催化中取代二价阳离子的机制仍不清楚。我们的结果使我们能够建议 Na+ 直接且特异性地替代锤头活性位点中的二价阳离子。由于从蛋白质数据库中目前最高分辨率的核酶结构获得的电子密度图的质量，预催化活性位点复合物的详细几何形状也以新的精度水平被揭示。
We have obtained a 1.55 Å crystal structure of a hammerhead ribozyme derived from Schistosoma mansoni in conditions that permit detailed observations of Na+ ion binding in the ribozyme's active site. At least two such Na+ ions are observed. The first Na+ ion binds to the N7 of G10.1 and the adjacent A9 phosphate in a manner identical to that previously observed for divalent cations. A second Na+ ion binds to the Hoogsteen face of G12, the general base in the hammerhead cleavage reaction, thereby potentially dissipating the negative charge of the catalytically active enolate form of the nucleotide base. A potential but more ambiguous third site bridges the A9 and scissile phosphates in a manner consistent with previous predictions. Hammerhead ribozymes have been observed to be active in the presence of high concentrations of monovalent cations, including Na+, but the mechanism by which monovalent cations substitute for divalent cations in hammerhead catalysis remains unclear. Our results enable us to suggest that Na+ directly and specifically substitutes for divalent cations in the hammerhead active site. The detailed geometry of the pre-catalytic active site complex is also revealed with a new level of precision, thanks to the quality of the electron density maps obtained from what is currently the highest resolution ribozyme structure in the protein data bank.
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影响因子：
4.6
作者：
Mähler J;Persson I
通讯作者：
Persson I
影响因子：
56.9
作者：
PRODY, GA;BAKOS, JT;BRUENING, G
通讯作者：
BRUENING, G
影响因子：
15
作者：
Lee, Tai-Sung;Lopez, Carlos Silva;York, Darrin M.
通讯作者：
York, Darrin M.
影响因子：
--
作者：
Martick, Monika;Lee, Tai-Sung;Scott, William G.
通讯作者：
Scott, William G.
DOI：
10.1107/s0907444902016657
发表时间：
2002-11-01
影响因子：
2.2
作者：
Adams, PD;Grosse-Kunstleve, RW;Terwilliger, TC
通讯作者：
Terwilliger, TC