The ASCC2 CUE domain contacts adjacent ubiquitins to recognize K63-linked polyubiquitin

Lombardi, P. M.; Haile, S.; Rusanov, T.; Rodell, R.; Anoh, R.; Baer, J. G.; Burke, K. A.; Gray, L. N.; Hacker, A. R.; Kebreau, K. R.; Ngandu, C. K.; Orland, H. A.; Osei-Asante, E.; Schmelyun, D. P.; Shorb, D. E.; Syed, S. H.; Veilleux, J. M.; Majumdar, A.; Mosammaparast, N.; Wolberger, C.

doi:10.1101/2021.10.17.464694

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bioRxiv · 10.1101/2021.10.17.464694

The ASCC2 CUE domain contacts adjacent ubiquitins to recognize K63-linked polyubiquitin

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Abstract

Alkylation of DNA and RNA is a potentially toxic lesion that can result in mutations and cell death. In response to alkylation damage, K63-linked polyubiquitin chains are assembled that localize the ALKBH3-ASCC repair complex to damage sites in the nucleus. The protein ASCC2, a subunit of the ASCC complex, selectively binds K63-linked polyubiquitin chains using its CUE domain, a type of ubiquitin-binding domain that typically binds monoubiquitin and does not discriminate among different polyubiquitin linkage types. We report here that the ASCC2 CUE domain selectively binds K63-linked diubiquitin by contacting both the distal and proximal ubiquitin. Whereas the ASCC2 CUE domain binds the distal ubiquitin in a manner similar to that reported for other CUE domains bound to a single ubiquitin, the contacts with the proximal ubiquitin are unique to ASCC2. The N-terminal portion of the ASCC2 1 helix, including residues E467 and S470, contributes to the binding interaction with the proximal ubiquitin of K63-linked diubiquitin. Mutation of residues within the N-terminal portion of the ASCC2 1 helix decreases ASCC2 recruitment in response to DNA alkylation, supporting the functional significance of these interactions during the alkylation damage response.

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Lombardi, P. M., Haile, S., Rusanov, T., Rodell, R., Anoh, R., Baer, J. G., Burke, K. A., Gray, L. N., Hacker, A. R., Kebreau, K. R., Ngandu, C. K., Orland, H. A., Osei-Asante, E., Schmelyun, D. P., Shorb, D. E., Syed, S. H., Veilleux, J. M., Majumdar, A., Mosammaparast, N., Wolberger, C.. 2021-10-17. The ASCC2 CUE domain contacts adjacent ubiquitins to recognize K63-linked polyubiquitin. https://doi.org/10.1101/2021.10.17.464694

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