Protein–Protein Interactions of ESCRT Complexes in the Yeast Saccharomyces cerevisiae

Authors

  • Katherine Bowers,

    Corresponding author
    1. Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 2XY, UK
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  • Jillian Lottridge,

    1. Institute of Molecular Biology, University of Oregon, Eugene, OR 97403–1229, USA
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  • Stephen B. Helliwell,

    1. Division of Biochemistry, Biozentrum, University of Basel, Klingelbergstrasse 70, CH4056 Basel, Switzerland
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  • Lisa M. Goldthwaite,

    1. Institute of Molecular Biology, University of Oregon, Eugene, OR 97403–1229, USA
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  • J. Paul Luzio,

    1. Cambridge Institute for Medical Research and Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 2XY, UK
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    •  J. Paul Luzio and Tom H. Stevens contributed equally to this work.

  • Tom H. Stevens

    1. Institute of Molecular Biology, University of Oregon, Eugene, OR 97403–1229, USA
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    •  J. Paul Luzio and Tom H. Stevens contributed equally to this work.


Katherine Bowers, kb123@cam.ac.uk

Abstract

Ten class E Vps proteins in yeast are known components of the ESCRT complexes I, II and III, which are required for the sorting of proteins to the lumenal membranes of multivesicular bodies. We used the yeast 2 hybrid system to analyze the protein–protein interactions of all 17 soluble class E Vps proteins, as well as proteins thought to be required for the ubiquitination and deubiquitination of cargo proteins at multivesicular bodies. We identified novel interactions between yeast ESCRT complex components suggesting that ESCRTI binds to both ESCRTII and ESCRTIII. These interactions were confirmed by GST pull-down experiments. Our data indicate that the link between ESCRTI and ESCRTIII is via Vps28p and Vps37p/Srn2p binding directly to Vps20p, as well as through indirect interactions via ESCRTII. This is in contrast to the situation in mammalian cells where ESCRTI and ESCRTIII interact indirectly via ALIX, the mammalian homologue of yeast proteins Vps31p/Bro1p and Rim20p. Our data also enable us to link all soluble class E Vps proteins to the ESCRT complexes. We propose the formation of a large multimeric complex on the endosome membrane consisting of ESCRTI, ESCRTII, ESCRTIII and other associated proteins.

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