Structural insight of human DEAD-box protein rck/p54 into its substrate recognition with conformational changes
Structural insight of human DEAD-box protein rck/p54 into its substrate recognition with conformational changes
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DOI：
10.1111/j.1365-2443.2006.00951.x
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发表时间：
2006-04-01
期刊：
影响因子：
2.1
通讯作者：
Tanaka, N
中科院分区：
文献类型：
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作者：
Matsui, T;Hogetsu, K;Tanaka, N
人rck/p54是B细胞淋巴瘤染色体易位基因t(11；14)(q23；q32)断裂点的产物，属于DEAD-box RNA解旋酶家族成员。这里，RCK/p54的N端核心区NC-RCK/p54的晶体结构表明，基序I中的P-环形成了一个封闭的构象，这是由RCK亚家族特有的残基Asn131诱导的。似乎ATP不与P-环结合。动态光散射结果揭示了ATP诱导的RCK/p54的构象变化。结果表明，游离RCK/p54是一种在溶液中膨胀的分子，在解开RNA时，N-末端核心结构域和C-末端结构域之间的结合途径是必不可少的。电子显微镜、ATP水解酶和荧光素酶检测结果表明，c-myc IRES RNA被rck/p54解开，表明它是rck/p54的良好底物，其二级结构调节IRES依赖的翻译。Rck/p54过表达导致HeLa细胞生长受抑，细胞周期停滞于G2/M期，c-myc表达下调。这些发现表明，rck/p54可能影响c-myc的IRES依赖性翻译，甚至在细胞中也是如此。
Human rck/p54, a product of the gene cloned at the breakpoint of t(11; 14) (q23;q32) chromosomal translocation on 11q23 in B-cell lymphoma, is a member of the DEAD-box RNA helicase family. Here, the crystal structure of Nc-rck/p54, the N-terminal core domain of rck/p54, revealed that the P-loop in motif I formed a closed conformation, which was induced by Asn131, a residue unique to the RCK subfamily. It appears that ATP does not bind to the P-loop. The results of dynamic light scattering revealed to ATP-induced conformational change of rck/p54. It was demonstrated that free rck/p54 is a distended molecule in solution, and that the approach between N-terminal core and C-terminal domains for ATP binding would be essential when unwinding RNA. The results from helicase assay using electron micrograph, ATP hydrolytic and luciferase assay showed that c-myc IRES RNA, whose secondary structure regulates IRES-dependant translation, was unwound by rck/p54 and indicated that it is a good substrate for rck/p54. Over-expression of rck/p54 in HeLa cells caused growth inhibition and cell cycle arrest at G2/M with down-regulation of c-myc expression. These findings altogether suggest that rck/p54 may affect the IRES-dependent translation of c-myc even in the cells.