Alternative function of a protein kinase homology domain in 2′,5′-oligoadenylate dependent RNase L
Alternative function of a protein kinase homology domain in 2′,5′-oligoadenylate dependent RNase L
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DOI：
10.1093/nar/27.2.439
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发表时间：
1999-01-15
影响因子：
14.9
通讯作者：
Silverman, RH
中科院分区：
文献类型：
--
作者：
Dong, BH;Silverman, RH
RNase L是在干扰素作用和细胞凋亡中起作用的2 '，5'-寡腺苷酸（P-SA）依赖性核糖核酸内切酶。RNase L的一个有趣的（尽管无法解释）特征是其与蛋白激酶的显著同源性。然而，尽管同源性，在与人RNase L的活化和RNA切割反应期间没有检测到蛋白激酶活性。类似地，RNase L的激酶加核糖核酸酶结构域不产生可检测的蛋白激酶活性，这与用相关激酶和核糖核酸内切酶（酵母IRE 1 p）的同源结构域获得的磷酸化相反。此外，ATP和pA（2 ′ p5 ′ A）（3）都不被RNase L水解，为了进一步研究RNase L中激酶同源性的功能，将蛋白激酶样结构域II中第392位残基的保守赖氨酸替换为精氨酸残基。所得突变体RNase L-K392 R显示2- 5A依赖性核糖核酸酶活性降低>100倍，而不降低2-5A或RNA结合活性。RNase L-K392 R活性的大幅降低与RNase L二聚化能力的缺陷相关。这些结果证明赖氨酸392在RNase L的活化和二聚化中的关键作用，从而表明这两种活性密切相关。
RNase L is the 2',5'-oligoadenylate (P-SA)-dependent endoribonuclease that functions in interferon action and apoptosis, One of the intriguing, albeit unexplained, features of RNase L is its significant homology to protein kinases, Despite the homology, however, no protein kinase activity was detected during activation and RNA cleavage reactions with human RNase L, Similarly, the kinase plus ribonuclease domains of RNase L produced no detectable protein kinase activity in contrast to the phosphorylation obtained with homologous domains of the related kinase and endoribonuclease, yeast IRE1p, In addition, neither ATP nor pA(2'p5'A)(3) was hydrolyzed by RNase L, To further investigate the function of the ki nase homology in RNase L, the conserved lysine at residue 392 in protein kinase-like domain II was replaced with an arginine residue. The resulting mutant, RNase L-K392R, showed >100-fold decreases in 2-5A-dependent ribonuclease activity without reducing 2-5A- or RNA-binding activities. The greatly reduced activity of RNase L-K392R was correlated to a defect in the ability of RNase L to dimerize, These results demonstrate a critical role for lysine 392 in the activation and dimerization of RNase L, thus suggesting that these two activities are intimately linked.