1
|
Mavridou V, King MS, Tavoulari S, Ruprecht JJ, Palmer SM, Kunji ERS. Substrate binding in the mitochondrial ADP/ATP carrier is a step-wise process guiding the structural changes in the transport cycle. Nat Commun 2022; 13:3585. [PMID: 35739110 PMCID: PMC9226169 DOI: 10.1038/s41467-022-31366-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 06/14/2022] [Indexed: 02/02/2023] Open
Abstract
Mitochondrial ADP/ATP carriers import ADP into the mitochondrial matrix and export ATP to the cytosol to fuel cellular processes. Structures of the inhibited cytoplasmic- and matrix-open states have confirmed an alternating access transport mechanism, but the molecular details of substrate binding remain unresolved. Here, we evaluate the role of the solvent-exposed residues of the translocation pathway in the process of substrate binding. We identify the main binding site, comprising three positively charged and a set of aliphatic and aromatic residues, which bind ADP and ATP in both states. Additionally, there are two pairs of asparagine/arginine residues on opposite sides of this site that are involved in substrate binding in a state-dependent manner. Thus, the substrates are directed through a series of binding poses, inducing the conformational changes of the carrier that lead to their translocation. The properties of this site explain the electrogenic and reversible nature of adenine nucleotide transport.
Collapse
Affiliation(s)
- Vasiliki Mavridou
- grid.5335.00000000121885934Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Keith Peters Building, Hills Road, Cambridge, CB2 0XY UK
| | - Martin S. King
- grid.5335.00000000121885934Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Keith Peters Building, Hills Road, Cambridge, CB2 0XY UK
| | - Sotiria Tavoulari
- grid.5335.00000000121885934Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Keith Peters Building, Hills Road, Cambridge, CB2 0XY UK
| | - Jonathan J. Ruprecht
- grid.5335.00000000121885934Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Keith Peters Building, Hills Road, Cambridge, CB2 0XY UK
| | - Shane M. Palmer
- grid.5335.00000000121885934Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Keith Peters Building, Hills Road, Cambridge, CB2 0XY UK
| | - Edmund R. S. Kunji
- grid.5335.00000000121885934Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Keith Peters Building, Hills Road, Cambridge, CB2 0XY UK
| |
Collapse
|
2
|
Taghon GJ, Rowe JB, Kapolka NJ, Isom DG. Predictable cholesterol binding sites in GPCRs lack consensus motifs. Structure 2021; 29:499-506.e3. [PMID: 33508215 PMCID: PMC9162085 DOI: 10.1016/j.str.2021.01.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 11/17/2020] [Accepted: 01/08/2021] [Indexed: 12/13/2022]
Abstract
A rich diversity of transmembrane G protein-coupled receptors (GPCRs) are used by eukaryotes to sense physical and chemical signals. In humans alone, 800 GPCRs comprise the largest and most therapeutically targeted receptor class. Recent advances in GPCR structural biology have produced hundreds of GPCR structures solved by X-ray diffraction and increasingly, cryo-electron microscopy (cryo-EM). Many of these structures are stabilized by site-specific cholesterol binding, but it is unclear whether these interactions are a product of recurring cholesterol-binding motifs and if observed patterns of cholesterol binding differ by experimental technique. Here, we comprehensively analyze the location and composition of cholesterol binding sites in the current set of 473 human GPCR structural chains. Our findings establish that cholesterol binds similarly in cryo-EM and X-ray structures and show that 92% of cholesterol molecules on GPCR surfaces reside in predictable locations that lack discernable cholesterol-binding motifs.
Collapse
Affiliation(s)
- Geoffrey J Taghon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, RMSB 6078A, Miami, FL 33136, USA
| | - Jacob B Rowe
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, RMSB 6078A, Miami, FL 33136, USA
| | - Nicholas J Kapolka
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, RMSB 6078A, Miami, FL 33136, USA
| | - Daniel G Isom
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, RMSB 6078A, Miami, FL 33136, USA; University of Miami Sylvester Comprehensive Cancer Center, Miami, FL 33136, USA; University of Miami Institute for Data Science and Computing, Miami, FL 33136, USA.
| |
Collapse
|