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Zess EK, Jensen C, Cruz-Mireles N, De la Concepcion JC, Sklenar J, Stephani M, Imre R, Roitinger E, Hughes R, Belhaj K, Mechtler K, Menke FLH, Bozkurt T, Banfield MJ, Kamoun S, Maqbool A, Dagdas YF. N-terminal β-strand underpins biochemical specialization of an ATG8 isoform. PLoS Biol 2019; 17:e3000373. [PMID: 31329577 PMCID: PMC6675122 DOI: 10.1371/journal.pbio.3000373] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 08/01/2019] [Accepted: 07/09/2019] [Indexed: 02/07/2023] Open
Abstract
Autophagy-related protein 8 (ATG8) is a highly conserved ubiquitin-like protein that modulates autophagy pathways by binding autophagic membranes and a number of proteins, including cargo receptors and core autophagy components. Throughout plant evolution, ATG8 has expanded from a single protein in algae to multiple isoforms in higher plants. However, the degree to which ATG8 isoforms have functionally specialized to bind distinct proteins remains unclear. Here, we describe a comprehensive protein-protein interaction resource, obtained using in planta immunoprecipitation (IP) followed by mass spectrometry (MS), to define the potato ATG8 interactome. We discovered that ATG8 isoforms bind distinct sets of plant proteins with varying degrees of overlap. This prompted us to define the biochemical basis of ATG8 specialization by comparing two potato ATG8 isoforms using both in vivo protein interaction assays and in vitro quantitative binding affinity analyses. These experiments revealed that the N-terminal β-strand-and, in particular, a single amino acid polymorphism-underpins binding specificity to the substrate PexRD54 by shaping the hydrophobic pocket that accommodates this protein's ATG8-interacting motif (AIM). Additional proteomics experiments indicated that the N-terminal β-strand shapes the broader ATG8 interactor profiles, defining interaction specificity with about 80 plant proteins. Our findings are consistent with the view that ATG8 isoforms comprise a layer of specificity in the regulation of selective autophagy pathways in plants.
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Affiliation(s)
- Erin K. Zess
- The Sainsbury Laboratory, University of East Anglia, Norwich, United Kingdom
| | - Cassandra Jensen
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Neftaly Cruz-Mireles
- The Sainsbury Laboratory, University of East Anglia, Norwich, United Kingdom
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Juan Carlos De la Concepcion
- The Sainsbury Laboratory, University of East Anglia, Norwich, United Kingdom
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Jan Sklenar
- The Sainsbury Laboratory, University of East Anglia, Norwich, United Kingdom
| | - Madlen Stephani
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| | - Richard Imre
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
- Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
- Institute of Molecular Biotechnology, Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| | - Elisabeth Roitinger
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
- Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
- Institute of Molecular Biotechnology, Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| | - Richard Hughes
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Khaoula Belhaj
- The Sainsbury Laboratory, University of East Anglia, Norwich, United Kingdom
| | - Karl Mechtler
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
- Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
- Institute of Molecular Biotechnology, Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| | - Frank L. H. Menke
- The Sainsbury Laboratory, University of East Anglia, Norwich, United Kingdom
| | - Tolga Bozkurt
- Imperial College London, Department of Life Sciences, London, United Kingdom
| | - Mark J. Banfield
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Sophien Kamoun
- The Sainsbury Laboratory, University of East Anglia, Norwich, United Kingdom
| | - Abbas Maqbool
- The Sainsbury Laboratory, University of East Anglia, Norwich, United Kingdom
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Yasin F. Dagdas
- The Sainsbury Laboratory, University of East Anglia, Norwich, United Kingdom
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
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