Solution structure of the first RNA recognition motif domain of human spliceosomal protein SF3b49 and its mode of interaction with a SF3b145 fragment |
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| Authors: | Kanako Kuwasako Nobukazu Nameki Kengo Tsuda Mari Takahashi Atsuko Sato Naoya Tochio Makoto Inoue Takaho Terada Takanori Kigawa Naohiro Kobayashi Mikako Shirouzu Takuhiro Ito Taiichi Sakamoto Kaori Wakamatsu Peter Güntert Seizo Takahashi Shigeyuki Yokoyama Yutaka Muto |
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| Institution: | 1. Faculty of Pharmacy and Research Institute of Pharmaceutical Sciences, Musashino University, Nishitokyo, Tokyo, Japan;2. RIKEN Systems and Structural Biology Center, Tsurumi‐ku, Yokohama, Japan;3. RIKEN Center for Life Science Technologies, Tsurumi‐ku, Yokohama, Japan;4. Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan;5. Department of Chemical & Biological Sciences, Japan Women's University, Mejirodai, Bunkyo, Tokyo, Japan;6. Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi‐Hiroshima, Hiroshima, Japan;7. Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, Narashino, Chiba, Japan;8. Tatsuo Miyazawa Memorial Program, RIKEN Genomic Sciences Center, Yokohama, Japan;9. Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance, and Frankfurt Institute of Advanced Studies, Goethe University Frankfurt, Frankfurt am Main, Germany;10. RIKEN Structural Biology Laboratory, Tsurumi‐ku, Yokohama, Japan |
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| Abstract: | The spliceosomal protein SF3b49, a component of the splicing factor 3b (SF3b) protein complex in the U2 small nuclear ribonucleoprotein, contains two RNA recognition motif (RRM) domains. In yeast, the first RRM domain (RRM1) of Hsh49 protein (yeast orthologue of human SF3b49) reportedly interacts with another component, Cus1 protein (orthologue of human SF3b145). Here, we solved the solution structure of the RRM1 of human SF3b49 and examined its mode of interaction with a fragment of human SF3b145 using NMR methods. Chemical shift mapping showed that the SF3b145 fragment spanning residues 598–631 interacts with SF3b49 RRM1, which adopts a canonical RRM fold with a topology of β1‐α1‐β2‐β3‐α2‐β4. Furthermore, a docking model based on NOESY measurements suggests that residues 607–616 of the SF3b145 fragment adopt a helical structure that binds to RRM1 predominantly via α1, consequently exhibiting a helix–helix interaction in almost antiparallel. This mode of interaction was confirmed by a mutational analysis using GST pull‐down assays. Comparison with structures of all RRM domains when complexed with a peptide found that this helix–helix interaction is unique to SF3b49 RRM1. Additionally, all amino acid residues involved in the interaction are well conserved among eukaryotes, suggesting evolutionary conservation of this interaction mode between SF3b49 RRM1 and SF3b145. |
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| Keywords: | nuclear magnetic resonance RNA recognition motif SF3b49 SF3b145 U2 snRNP |
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