The electrostatic character of the ribosomal surface enables extraordinarily rapid target location by ribotoxins
The electrostatic character of the ribosomal surface enables extraordinarily rapid target location by ribotoxins
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DOI：
10.1038/nsmb1082
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发表时间：
2006-05-01
影响因子：
16.8
通讯作者：
Correll, CC
中科院分区：
文献类型：
--
作者：
Korennykh, AV;Piccirilli, JA;Correll, CC
α-八叠球菌素核糖毒素包括一个独特的核糖核酸酶家族，其通过催化核糖体RNA在八叠球菌素/蓖麻毒蛋白环（SRL）中特定位置的核糖核酸内切酶裂解来削弱核糖体。SRL结构单独被核糖毒素位点特异性地切割，但核糖体环境将反应速率提高了几个数量级。我们表明，对于α-八叠球菌素样核糖毒素restrictocin，这种催化优势来自有利的静电相互作用与核糖体。限制曲菌素结合在核糖体表面的许多位点上，并在一定条件下以1.7 × 10（10）M-1 s（-1）的二级速率常数切割SRL，该值与限制曲菌素-核糖体随机相遇的预测频率相匹配。结果表明，限制曲肽遇到核糖体随机和扩散的核糖体静电场内的SRL的目标定位的机制。这些研究显示了静电在蛋白质-核糖体识别中的作用。
alpha-sarcin ribotoxins comprise a unique family of ribonucleases that cripple the ribosome by catalyzing endoribonucleolytic cleavage of ribosomal RNA at a specific location in the sarcin/ricin loop (SRL). The SRL structure alone is cleaved site-specifically by the ribotoxin, but the ribosomal context enhances the reaction rate by several orders of magnitude. We show that, for the alpha-sarcin-like ribotoxin restrictocin, this catalytic advantage arises from favorable electrostatic interactions with the ribosome. Restrictocin binds at many sites on the ribosomal surface and under certain conditions cleaves the SRL with a second-order rate constant of 1.7 x 10(10) M-1 s(-1), a value that matches the predicted frequency of random restrictocin-ribosome encounters. The results suggest a mechanism of target location whereby restrictocin encounters ribosomes randomly and diffuses within the ribosomal electrostatic field to the SRL. These studies show a role for electrostatics in protein-ribosome recognition.