The ESCRT-III Adaptor Protein Bro1 Controls Functions of Regulator for Free Ubiquitin Chains 1 (Rfu1) in Ubiquitin Homeostasis |
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| Authors: | Yoko Kimura Junko Kawawaki Yukie Kakiyama Ayumi Shimoda Keiji Tanaka |
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| Affiliation: | From the ‡Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 113-8613 and ;the §Department of Applied Biological Chemistry, Graduate School of Agriculture, Shizuoka University, Shizuoka 422-8529, Japan |
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| Abstract: | Yeast Rfu1 (regulator for free ubiquitin chain 1) localizes to endosomes and plays a role in ubiquitin homeostasis by inhibiting the activity of Doa4. We show that Bro1, a member of the class E vacuolar protein sorting proteins that recruits Doa4 to endosomes and stimulates Doa4 deubiquitinating activity, also recruits Rfu1 to endosomes for involvement in ubiquitin homeostasis. This recruitment was mediated by the direct interaction between a region containing the YPEL motif in Rfu1 and the V domain in Bro1, which could be analogous to the interaction between the mammalian Alix V domain and YPXnL motifs of viral and cellular proteins. Furthermore, overexpression of Bro1, particularly the V domain, prevented Rfu1 degradation in response to heat shock. Thus, Bro1, a Doa4 positive regulator, regulated Rfu1, a negative regulator of Doa4. Rfu1 degradation partly involved the proteasome and a ubiquitin ligase Rsp5, suggesting that Rfu1 stability was regulated by ubiquitin-proteasome pathways. |
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| Keywords: | Cell Biology Deubiquitination Endosome Protein Degradation Stress Response Ubiquitin Ubiquitin Ligase Heat Shock |
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