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 m7 GDP and...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 m7 GDP and m227GDP 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 m7 GDP 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.展开更多
基金the Natural Science Foundation of China(No.30870118)。
文摘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 m7 GDP and m227GDP 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 m7 GDP 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.
