Evidence for a hydroxide ion bridging two magnesium ions at the active site of the hammerhead ribozyme.
Evidence for a hydroxide ion bridging two magnesium ions at the active site of the hammerhead ribozyme.
复制标题
氢氧根离子在锤头核酶活性位点桥接两个镁离子的证据。
DOI：
10.1093/nar/25.17.3421
复制
发表时间：
1997
影响因子：
14.9
通讯作者：
Westhof,E
中科院分区：
文献类型：
--
作者：
Hermann,T;Auffinger,P;Scott,WG;Westhof,E
In the presence of magnesium ions, cleavage by the hammerhead ribozyme RNA at a specific residue leads to 2′3′-cyclic phosphate and 5′-OH extremities. In the cleavage reaction an activated ribose 2′-hydroxyl group attacks its attached 3′-phosphate. Molecular dynamics simulations of the crystal structure of the hammerhead ribozyme, obtained after flash-freezing of crystals under conditions where the ribozyme is active, provide evidence that a μ-bridging OH−ion is located between two Mg2+ions close to the cleavable phosphate. Constrained simulations show further that a flip from the C3′-endoto the C2′-endoconformation of the ribose at the cleavable phosphate brings the 2′-hydroxyl in proximity to both the attacked phosphorous atom and the μ-bridging OH−ion. Thus, the simulations lead to a detailed new insight into the mechanism of hammerhead ribozyme cleavage where a μ-hydroxo bridged magnesium cluster, located on the deep groove side, provides an OH−ion that is able to activate the 2′-hydroxyl nucleophile after a minor and localized conformational change in the RNA.
