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Leznicki P, Korac-Prlic J, Kliza K, Husnjak K, Nyathi Y, Dikic I, High S. Binding of SGTA to Rpn13 selectively modulates protein quality control. J Cell Sci 2015; 128:3187-96. [PMID: 26169395 PMCID: PMC4582187 DOI: 10.1242/jcs.165209] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 07/03/2015] [Indexed: 12/16/2022] Open
Abstract
Rpn13 is an intrinsic ubiquitin receptor of the 26S proteasome regulatory subunit that facilitates substrate capture prior to degradation. Here we show that the C-terminal region of Rpn13 binds to the tetratricopeptide repeat (TPR) domain of SGTA, a cytosolic factor implicated in the quality control of mislocalised membrane proteins (MLPs). The overexpression of SGTA results in a substantial increase in steady-state MLP levels, consistent with an effect on proteasomal degradation. However, this effect is strongly dependent upon the interaction of SGTA with the proteasomal component Rpn13. Hence, overexpression of the SGTA-binding region of Rpn13 or point mutations within the SGTA TPR domain both inhibit SGTA binding to the proteasome and substantially reduce MLP levels. These findings suggest that SGTA can regulate the access of MLPs to the proteolytic core of the proteasome, implying that a protein quality control cycle that involves SGTA and the BAG6 complex can operate at the 19S regulatory particle. We speculate that the binding of SGTA to Rpn13 enables specific polypeptides to escape proteasomal degradation and/or selectively modulates substrate degradation. Highlighted Article: Binding of SGTA to the proteasome delays substrate degradation, thereby providing a mechanism for potentially viable proteins to be rescued for reuse.
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Affiliation(s)
- Pawel Leznicki
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Jelena Korac-Prlic
- Department of Immunology and Medical Genetics, School of Medicine, University of Split, Soltanska 2, Split 21000, Croatia
| | - Katarzyna Kliza
- Institute of Biochemistry II, School of Medicine, Goethe University, Theodor-Stern-Kai 7, Frankfurt (Main) 60590, Germany
| | - Koraljka Husnjak
- Institute of Biochemistry II, School of Medicine, Goethe University, Theodor-Stern-Kai 7, Frankfurt (Main) 60590, Germany
| | - Yvonne Nyathi
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Ivan Dikic
- Department of Immunology and Medical Genetics, School of Medicine, University of Split, Soltanska 2, Split 21000, Croatia Institute of Biochemistry II, School of Medicine, Goethe University, Theodor-Stern-Kai 7, Frankfurt (Main) 60590, Germany Buchmann Institute for Molecular Life Sciences, School of Medicine, Goethe University, Theodor-Stern-Kai 7, Frankfurt (Main) 60590, Germany
| | - Stephen High
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
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