Ubiquitin receptor proteins hHR23a and hPLIC2 interact |
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Authors: | Kang Yang Zhang Naixia Koepp Deanna M Walters Kylie J |
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Affiliation: | Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA. |
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Abstract: | Ubiquitin receptor proteins play an important role in delivering ubiquitylated protein substrates to the proteasome for degradation. HHR23a and hPLIC2 are two such ubiquitin receptors that contain ubiquitin-like (UBL) domains, which interact with the proteasome, and ubiquitin-associated (UBA) domains, which interact with ubiquitin. Depending on their abundance UBL/UBA family members can either promote or inhibit the degradation of other proteins, which suggests their participation in the delivery of substrates to the proteasome is highly regulated. In previous work, we determined UBL/UBA domain interactions to promote intramolecular interactions in hHR23a that are abrogated with the addition of either ubiquitin or the proteasome component S5a. In yeast, we determined the hHR23a ortholog (Rad23) to interact with another UBL/UBA family member (Ddi1) and to bind a common tetraubiquitin chain. Here, we use NMR spectroscopy to reveal that hHR23a interacts with hPLIC2 via UBL/UBA domain interactions and to map their binding surfaces. In addition, we demonstrate that these two proteins associate in mammalian cells. Intriguingly, inhibition of the proteasome mitigates hHR23a/hPLIC2 interaction. |
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Keywords: | hHR23, human homolog of Rad23 hPLIC2, human homolog 2 of protein linking integrin-associated protein and cytoskeleton HSQC, heteronuclear single quantum coherence UBA, ubiquitin-associated UBL, ubiquitin-like |
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