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Denisov IG, Sligar SG. Nanodiscs for the study of membrane proteins. Curr Opin Struct Biol 2024; 87:102844. [PMID: 38795563 PMCID: PMC11283964 DOI: 10.1016/j.sbi.2024.102844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/25/2024] [Accepted: 05/03/2024] [Indexed: 05/28/2024]
Abstract
Nanodiscs represent a versatile tool for studies of membrane proteins and protein-membrane interactions under native-like conditions. Multiple variations of the Nanodisc platform, as well as new experimental methods, have been recently developed to understand various aspects of structure, dynamics and functional properties of systems involved in signaling, transport, blood coagulation and many other critically important processes. In this mini-review, we focus on some of these exciting recent developments that utilize the Nanodisc platform.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
| | - Stephen G Sligar
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA.
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Gill KS, Mehta K, Heredia JD, Krishnamurthy VV, Zhang K, Procko E. Multiple mechanisms of self-association of chemokine receptors CXCR4 and CCR5 demonstrated by deep mutagenesis. J Biol Chem 2023; 299:105229. [PMID: 37690681 PMCID: PMC10551899 DOI: 10.1016/j.jbc.2023.105229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 08/24/2023] [Accepted: 09/04/2023] [Indexed: 09/12/2023] Open
Abstract
Chemokine receptors are members of the rhodopsin-like class A GPCRs whose signaling through G proteins drives the directional movement of cells in response to a chemokine gradient. Chemokine receptors CXCR4 and CCR5 have been extensively studied due to their roles in leukocyte development and inflammation and their status as coreceptors for HIV-1 infection, among other roles. Both receptors form dimers or oligomers of unclear function. While CXCR4 has been crystallized in a dimeric arrangement, available atomic resolution structures of CCR5 are monomeric. To investigate their dimerization interfaces, we used a bimolecular fluorescence complementation (BiFC)-based screen and deep mutational scanning to find mutations that change how the receptors self-associate, either via specific oligomer assembly or alternative mechanisms of clustering in close proximity. Many disruptive mutations promoted self-associations nonspecifically, suggesting they aggregated in the membrane. A mutationally intolerant region was found on CXCR4 that matched the crystallographic dimer interface, supporting this dimeric arrangement in living cells. A mutationally intolerant region was also observed on the surface of CCR5 by transmembrane helices 3 and 4. Mutations predicted from the scan to reduce BiFC were validated and were localized in the transmembrane domains as well as the C-terminal cytoplasmic tails where they reduced lipid microdomain localization. A mutation in the dimer interface of CXCR4 had increased binding to the ligand CXCL12 and yet diminished calcium signaling. There was no change in syncytia formation with cells expressing HIV-1 Env. The data highlight that multiple mechanisms are involved in self-association of chemokine receptor chains.
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Affiliation(s)
- Kevin S Gill
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA
| | - Kritika Mehta
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA
| | - Jeremiah D Heredia
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA
| | | | - Kai Zhang
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA
| | - Erik Procko
- Department of Biochemistry, University of Illinois, Urbana, Illinois, USA; Cyrus Biotechnology, Seattle, Washington, USA.
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Manzer ZA, Selivanovitch E, Ostwalt AR, Daniel S. Membrane protein synthesis: no cells required. Trends Biochem Sci 2023; 48:642-654. [PMID: 37087310 DOI: 10.1016/j.tibs.2023.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 02/20/2023] [Accepted: 03/22/2023] [Indexed: 04/24/2023]
Abstract
Despite advances in membrane protein (MP) structural biology and a growing interest in their applications, these proteins remain challenging to study. Progress has been hindered by the complex nature of MPs and innovative methods will be required to circumvent technical hurdles. Cell-free protein synthesis (CFPS) is a burgeoning technique for synthesizing MPs directly into a membrane environment using reconstituted components of the cellular transcription and translation machinery in vitro. We provide an overview of CFPS and how this technique can be applied to the synthesis and study of MPs. We highlight numerous strategies including synthesis methods and folding environments, each with advantages and limitations, to provide a survey of how CFPS techniques can advance the study of MPs.
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Affiliation(s)
- Zachary A Manzer
- R.F. School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Ekaterina Selivanovitch
- R.F. School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Alexis R Ostwalt
- R.F. School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Susan Daniel
- R.F. School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA.
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Gill KS, Mehta K, Heredia JD, Krishnamurthy VV, Zhang K, Procko E. Multiple mechanisms of self-association of chemokine receptors CXCR4 and CCR5 demonstrated by deep mutagenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.25.534231. [PMID: 36993221 PMCID: PMC10055436 DOI: 10.1101/2023.03.25.534231] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Chemokine receptors are members of the rhodopsin-like class A GPCRs whose signaling through G proteins drives the directional movement of cells in response to a chemokine gradient. Chemokine receptors CXCR4 and CCR5 have been extensively studied due to their roles in white blood cell development and inflammation and their status as coreceptors for HIV-1 infection, among other functions. Both receptors form dimers or oligomers but the function/s of self-associations are unclear. While CXCR4 has been crystallized in a dimeric arrangement, available atomic resolution structures of CCR5 are monomeric. To investigate the dimerization interfaces of these chemokine receptors, we used a bimolecular fluorescence complementation (BiFC)-based screen and deep mutational scanning to find mutations that modify receptor self-association. Many disruptive mutations promoted self-associations nonspecifically, suggesting they aggregated in the membrane. A mutationally intolerant region was found on CXCR4 that matched the crystallographic dimer interface, supporting this dimeric arrangement in living cells. A mutationally intolerant region was also observed on the surface of CCR5 by transmembrane helices 3 and 4. Mutations from the deep mutational scan that reduce BiFC were validated and were localized in the transmembrane domains as well as the C-terminal cytoplasmic tails where they reduced lipid microdomain localization. The reduced self-association mutants of CXCR4 had increased binding to the ligand CXCL12 but diminished calcium signaling. There was no change in syncytia formation with cells expressing HIV-1 Env. The data highlight that multiple mechanisms are involved in self-association of chemokine receptor chains.
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Affiliation(s)
- Kevin S Gill
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
| | - Kritika Mehta
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
| | - Jeremiah D Heredia
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
- Current affiliation: Codexis, Redwood City, CA 94063
| | | | - Kai Zhang
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
| | - Erik Procko
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
- Cyrus Biotechnology, Seattle, WA 98121, USA
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Hancock AM, Son M, Nairat M, Wei T, Jeuken LJC, Duffy CDP, Schlau-Cohen GS, Adams PG. Ultrafast energy transfer between lipid-linked chromophores and plant light-harvesting complex II. Phys Chem Chem Phys 2021; 23:19511-19524. [PMID: 34524278 PMCID: PMC8442836 DOI: 10.1039/d1cp01628h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Light-Harvesting Complex II (LHCII) is a membrane protein found in plant chloroplasts that has the crucial role of absorbing solar energy and subsequently performing excitation energy transfer to the reaction centre subunits of Photosystem II. LHCII provides strong absorption of blue and red light, however, it has minimal absorption in the green spectral region where solar irradiance is maximal. In a recent proof-of-principle study, we enhanced the absorption in this spectral range by developing a biohybrid system where LHCII proteins together with lipid-linked Texas Red (TR) chromophores were assembled into lipid membrane vesicles. The utility of these systems was limited by significant LHCII quenching due to protein-protein interactions and heterogeneous lipid structures. Here, we organise TR and LHCII into a lipid nanodisc, which provides a homogeneous, well-controlled platform to study the interactions between TR molecules and single LHCII complexes. Fluorescence spectroscopy determined that TR-to-LHCII energy transfer has an efficiency of at least 60%, resulting in a 262% enhancement of LHCII fluorescence in the 525-625 nm range, two-fold greater than in the previous system. Ultrafast transient absorption spectroscopy revealed two time constants of 3.7 and 128 ps for TR-to-LHCII energy transfer. Structural modelling and theoretical calculations indicate that these timescales correspond to TR-lipids that are loosely- or tightly-associated with the protein, respectively, with estimated TR-to-LHCII separations of ∼3.5 nm and ∼1 nm. Overall, we demonstrate that a nanodisc-based biohybrid system provides an idealised platform to explore the photophysical interactions between extrinsic chromophores and membrane proteins with potential applications in understanding more complex natural or artificial photosynthetic systems.
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Affiliation(s)
- Ashley M Hancock
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. .,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Minjung Son
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA.
| | - Muath Nairat
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA.
| | - Tiejun Wei
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Lars J C Jeuken
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.,Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.,Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
| | - Christopher D P Duffy
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Gabriela S Schlau-Cohen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA.
| | - Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. .,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
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