hNUDT16: a universal decapping enzyme for small nucleolar RNA and cytoplasmic mRNA
hNUDT16: a universal decapping enzyme for small nucleolar RNA and cytoplasmic mRNA
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DOI：
10.1007/s13238-011-1009-2
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发表时间：
2011-01-01
期刊：
影响因子：
21.1
通讯作者：
Yan, Jinghua
中科院分区：
文献类型：
--
作者：
Lu, Guangwen;Zhang, Jie;Yan, Jinghua
人NUDT16(HNUDT16)是一种脱氧核糖核酸酶，最初被鉴定为非洲爪哇X29的人类同源物。作为一种金属酶，hNUDT16依赖于二价阳离子的帽子水解活性来去除RNA中的m(7)GDP和m(227)GDP。金属也决定了酶的底物专一性。到目前为止，只有U8小核仁RNA(SnoRNA)被鉴定为hNUDT16在镁离子存在下的底物。在这里，我们证明了除了U8，hNUDT16还可以在Mg2+或Mn2+存在的情况下主动从mRNAs中切割m7GDP帽。我们进一步表明，通过我们的交叉抑制和定量去除法，hNUDT16不优先识别U8或mRNA底物。此外，我们的突变分析确定了几个参与水解的关键残基，并证实了REXXEE基序在催化中的关键作用。最后，对hNUDT16的亚细胞定位的研究表明，它在细胞质和细胞核中都有丰富的表达。这些发现将hNUDT16的底物谱扩展到snoRNAs之外，也包括mRNA，表明了hNUDT16的多效性去包裹活性。
Human NUDT16 (hNUDT16) is a decapping enzyme initially identified as the human homolog to the Xenopus laevis X29. As a metalloenzyme, hNUDT16 relies on divalent cations for its cap-hydrolysis activity to remove m(7)GDP and m(227)GDP from RNAs. Metal also determines substrate specificity of the enzyme. So far, only U8 small nucleolar RNA (snoRNA) has been identified as the substrate of hNUDT16 in the presence of Mg2+. Here we demonstrate that besides U8, hNUDT16 can also actively cleave the m7GDP cap from mRNAs in the presence of Mg2+ or Mn2+. We further show that hNUDT16 does not preferentially recognize U8 or mRNA substrates by our cross-inhibition and quantitative decapping assays. In addition, our mutagenesis analysis identifies several key residues involved in hydrolysis and confirms the key role of the REXXEE motif in catalysis. Finally an investigation into the subcellular localization of hNUDT16 revealed its abundance in both cytoplasm and nucleus. These findings extend the substrate spectrum of hNUDT16 beyond snoRNAs to also include mRNA, demonstrating the pleiotropic decapping activity of hNUDT16.