Structural basis for specific recognition of Lys 63‐linked polyubiquitin chains by tandem UIMs of RAP80 |
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Authors: | Yusuke Sato Azusa Yoshikawa Hisatoshi Mimura Masami Yamashita Atsushi Yamagata Shuya Fukai |
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Institution: | 1. Structural Biology Laboratory, Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan;2. Department of Biological Information, Tokyo Institute of Technology, Yokohama, Japan;3. Department of Medical Genome Sciences, Graduate School of Frontier Sciences, the University of Tokyo, Chiba, Japan |
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Abstract: | RAP80 has a key role in the recruitment of the Abraxas–BRCC36–BRCA1–BARD1 complex to DNA‐damage foci for DNA repair through specific recognition of Lys 63‐linked polyubiquitinated proteins by its tandem ubiquitin‐interacting motifs (UIMs). Here, we report the crystal structure of the RAP80 tandem UIMs (RAP80‐UIM1‐UIM2) in complex with Lys 63‐linked di‐ubiquitin at 2.2 Å resolution. The two UIMs, UIM1 and UIM2, and the α‐helical inter‐UIM region together form a continuous 60 Å‐long α‐helix. UIM1 and UIM2 bind to the proximal and distal ubiquitin moieties, respectively. Both UIM1 and UIM2 of RAP80 recognize an Ile 44‐centered hydrophobic patch on ubiquitin but neither UIM interacts with the Lys 63‐linked isopeptide bond. Our structure suggests that the inter‐UIM region forms a 12 Å‐long α‐helix that ensures that the UIMs are arranged to enable specific binding of Lys 63‐linked di‐ubiquitin. This was confirmed by pull‐down analyses using RAP80‐UIM1‐UIM2 mutants of various length inter‐UIM regions. Further, we show that the Epsin1 tandem UIM, which has an inter‐UIM region similar to that of RAP80‐UIM1‐UIM2, also selectively binds Lys 63‐linked di‐ubiquitin. |
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Keywords: | crystallography DNA repair ubiquitin ubiquitin‐interacting motif |
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