Biochemical Differences and Similarities between the DEAD-Box Helicase Orthologs DDX3X and Ded1p.
Biochemical Differences and Similarities between the DEAD-Box Helicase Orthologs DDX3X and Ded1p.
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DOI：
10.1016/j.jmb.2017.10.008
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发表时间：
2017-11-24
影响因子：
5.6
通讯作者：
Jankowsky E
中科院分区：
文献类型：
--
作者：
Sharma D;Putnam AA;Jankowsky E
DDX3X是一种保守的DEAD盒RNA解旋酶，参与翻译起始和其他RNA代谢过程。人类DDX3X突变及其表达失调与肿瘤发生和智力残疾有关。该蛋白质也被多种病毒靶向。以前的研究表明DDX3X的解旋酶和NTR活性，但酶的重要生化特征仍不清楚。在这里，我们系统地描述了人DDX3X的酶活性，并将其与其密切相关的S。酿酒酵母直向同源物Ded1p.我们表明，DDX3X，像Ded1p，专门利用腺苷三磷酸解开螺旋，寡聚体作为有效的RNA解旋酶的功能，并不解开DNA双链体。DDX 3X的ATP酶活性被RNA显著地刺激，而被DNA较弱地刺激，尽管DNA与该酶结合。对于RNA解旋，DDX3X显示出比Ded1p更大的偏好性，对于双链体3′端未配对区域的底物，而不是5′端未配对区域的底物。DDX3X比Ded1p更快地分离较长的RNA双链体，并且在促进链退火方面不如Ded1p有效。我们的研究结果表明，人DDX3X的生化活性是典型的DEAD盒RNA解旋酶，但在数量上不同于其高度相似的S。酿酒酵母直向同源物Ded1p.
DDX3X is a conserved DEAD-box RNA helicase involved in translation initiation and other processes of RNA metabolism. Mutations in human DDX3X and deregulation of its expression are linked to tumorigenesis and intellectual disability. The protein is also targeted by diverse viruses. Previous studies demonstrated helicase and NTPase activities for DDX3X, but important biochemical features of the enzyme remain unclear. Here, we systematically characterize enzymatic activities of human DDX3X and compare these to its closely related S. cerevisiae ortholog Ded1p. We show that DDX3X, like Ded1p, exclusively utilizes adenosine triphosphates to unwind helices, oligomerizes to function as efficient RNA helicase, and does not unwind DNA duplexes. The ATPase activity of DDX3X is markedly stimulated by RNA and weaker by DNA, although DNA binds to the enzyme. For RNA unwinding, DDX3X shows a greater preference than Ded1p for substrates with unpaired regions 3′ to the duplex over those with 5′ unpaired regions. DDX3X separates longer RNA duplexes faster than Ded1p and is less potent than Ded1p in facilitating strand annealing. Our results reveal that the biochemical activities of human DDX3X are typical for DEAD-box RNA helicases, but diverge quantitatively from its highly similar S. cerevisiae ortholog Ded1p.
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影响因子：
5.6
作者：
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通讯作者：
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