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Young JW, Wason IS, Zhao Z, Kim S, Aoki H, Phanse S, Rattray DG, Foster LJ, Babu M, Duong van Hoa F. Development of a Method Combining Peptidiscs and Proteomics to Identify, Stabilize, and Purify a Detergent-Sensitive Membrane Protein Assembly. J Proteome Res 2022; 21:1748-1758. [PMID: 35616533 DOI: 10.1021/acs.jproteome.2c00129] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The peptidisc membrane mimetic enables global reconstitution of the bacterial membrane proteome into water-soluble detergent-free particles, termed peptidisc libraries. We present here a method that combines peptidisc libraries and chromosomal-level gene tagging technology with affinity purification and mass spectrometry (AP/MS) to stabilize and identify fragile membrane protein complexes that exist at native expression levels. This method circumvents common artifacts caused by bait protein overproduction and protein complex dissociation due to lengthy exposure to detergents during protein isolation. Using the Escherichia coli Sec system as a case study, we identify an expanded version of the translocon, termed the HMD complex, consisting of nine different integral membrane subunits. This complex is stable in peptidiscs but dissociates in detergents. Guided by this native-level proteomic information, we design and validate a procedure that enables purification of the HMD complex with minimal protein dissociation. These results highlight the utility of peptidiscs and AP/MS to discover and stabilize fragile membrane protein assemblies. Data are available via ProteomeXchange with identifier PXD032315.
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Affiliation(s)
- John William Young
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Irvinder Singh Wason
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Zhiyu Zhao
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Sunyoung Kim
- Department of Biochemistry, Faculty of Science, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Hiroyuki Aoki
- Department of Biochemistry, Faculty of Science, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Sadhna Phanse
- Department of Biochemistry, Faculty of Science, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - David G Rattray
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Michael Smith Laboratory, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Leonard J Foster
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Michael Smith Laboratory, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Mohan Babu
- Department of Biochemistry, Faculty of Science, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Franck Duong van Hoa
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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McCafferty CL, Taylor DW, Marcotte EM. Improving integrative 3D modeling into low- to medium-resolution electron microscopy structures with evolutionary couplings. Protein Sci 2021; 30:1006-1021. [PMID: 33759266 PMCID: PMC8040867 DOI: 10.1002/pro.4067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 03/16/2021] [Accepted: 03/16/2021] [Indexed: 12/12/2022]
Abstract
Electron microscopy (EM) continues to provide near-atomic resolution structures for well-behaved proteins and protein complexes. Unfortunately, structures of some complexes are limited to low- to medium-resolution due to biochemical or conformational heterogeneity. Thus, the application of unbiased systematic methods for fitting individual structures into EM maps is important. A method that employs co-evolutionary information obtained solely from sequence data could prove invaluable for quick, confident localization of subunits within these structures. Here, we incorporate the co-evolution of intermolecular amino acids as a new type of distance restraint in the integrative modeling platform in order to build three-dimensional models of atomic structures into EM maps ranging from 10-14 Å in resolution. We validate this method using four complexes of known structure, where we highlight the conservation of intermolecular couplings despite dynamic conformational changes using the BAM complex. Finally, we use this method to assemble the subunits of the bacterial holo-translocon into a model that agrees with previous biochemical data. The use of evolutionary couplings in integrative modeling improves systematic, unbiased fitting of atomic models into medium- to low-resolution EM maps, providing additional information to integrative models lacking in spatial data.
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Affiliation(s)
| | - David W. Taylor
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTexasUSA
- Center for Systems and Synthetic BiologyUniversity of Texas at AustinAustinTexasUSA
- LIVESTRONG Cancer InstitutesDell Medical SchoolAustinTexasUSA
| | - Edward M. Marcotte
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTexasUSA
- Center for Systems and Synthetic BiologyUniversity of Texas at AustinAustinTexasUSA
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