Structural insights into Gemin5-guided selection of pre-snRNAs for snRNP assembly
- Chao Xu1,2,3,
- Hideaki Ishikawa4,
- Keiichi Izumikawa4,
- Li Li3,
- Hao He3,
- Yuko Nobe5,
- Yoshio Yamauchi5,
- Hanief M. Shahjee6,
- Xian-Hui Wu3,
- Yi-tao Yu6,
- Toshiaki Isobe5,
- Nobuhiro Takahashi4 and
- Jinrong Min3,7
- 1Hefei National Laboratory for Physical Sciences at Microscale, Hefei Science Center of CAS, Chinese Academy of Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China;
- 2Key Laboratory of Structural Biology, Hefei Science Center of CAS, Chinese Academy of Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China;
- 3Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada;
- 4Department of Applied Biological Science, Graduate School of Agriculture and Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Fuchu-Shi, Tokyo 183-8509, Japan;
- 5Department of Chemistry, Tokyo Metropolitan University, Hachiouji-shi, Tokyo 192-0397, Japan;
- 6Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA;
- 7Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Corresponding authors: xuchaor{at}ustc.edu.cn, jr.min{at}utoronto.ca
Abstract
In cytoplasm, the survival of motor neuron (SMN) complex delivers pre-small nuclear RNAs (pre-snRNAs) to the heptameric Sm ring for the assembly of the ring complex on pre-snRNAs at the conserved Sm site [A(U)4–6G]. Gemin5, a WD40 protein component of the SMN complex, is responsible for recognizing pre-snRNAs. In addition, Gemin5 has been reported to specifically bind to the m7G cap. In this study, we show that the WD40 domain of Gemin5 is both necessary and sufficient for binding the Sm site of pre-snRNAs by isothermal titration calorimetry (ITC) and mutagenesis assays. We further determined the crystal structures of the WD40 domain of Gemin5 in complex with the Sm site or m7G cap of pre-snRNA, which reveal that the WD40 domain of Gemin5 recognizes the Sm site and m7G cap of pre-snRNAs via two distinct binding sites by respective base-specific interactions. In addition, we also uncovered a novel role of Gemin5 in escorting the truncated forms of U1 pre-snRNAs for proper disposal. Overall, the elucidated Gemin5 structures will contribute to a better understanding of Gemin5 in small nuclear ribonucleic protein (snRNP) biogenesis as well as, potentially, other cellular activities.
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Footnotes
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Supplemental material is available for this article.
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Article published online ahead of print. Article and publication date are online at http://www.genesdev.org/cgi/doi/10.1101/gad.288340.116.
- Received August 1, 2016.
- Accepted September 26, 2016.
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