Differences in SMA-like polymer architecture dictate the conformational changes exhibited by the membrane protein rhodopsin encapsulated in lipid nano-particles

Grime, Rachael L.; Logan, Richard T; Nestorow, Stephanie A; Sridhar, Pooja; Edwards, Patricia C.; Tate, Christopher G.; Klumperman, Bert; Dafforn, Timothy R.; Poyner, David R.; Reeves, Philip J.; Wheatley, Mark

doi:10.1039/d1nr02419a

Cited by 12 publications

(6 citation statements)

References 49 publications

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“…Although beyond the scope of this work, it should be noted that varying copolymer properties may affect the functionality of membrane proteins. 73 …”

Section: Resultsmentioning

confidence: 99%

“…Last but not least, halogenated copolymers may be useful for dedicated biophysical techniques, e.g., the use of (i) fluorinated copolymers, such as 4-CF 3 SMA, for 19 F-NMR studies, (ii) brominated copolymers for MS experiments due to their convenient isotopic signature, and (iii) copolymers with heavier halogens (i.e., 4-BrSMA or 4-ISMA) for EM microscopy where the polymers/particles could potentially be visualized more easily due to the scattering of the dense halogen atoms. Although beyond the scope of this work, it should be noted that varying copolymer properties may affect the functionality of membrane proteins …”

Section: Resultsmentioning

confidence: 99%

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Synthesis and Evaluation of a Library of Alternating Amphipathic Copolymers to Solubilize and Study Membrane Proteins

et al. 2022

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Amphipathic copolymers such as poly(styrene-maleic acid) (SMA) are promising tools for the facile extraction of membrane proteins (MPs) into native nanodiscs. Here, we designed and synthesized a library of well-defined alternating copolymers of SMA analogues in order to elucidate polymer properties that are important for MP solubilization and stability. MP extraction efficiency was determined using KcsA from E. coli membranes, and general solubilization efficiency was investigated via turbidimetry experiments on membranes of E. coli , yeast mitochondria, and synthetic lipids. Remarkably, halogenation of SMA copolymers dramatically improved solubilization efficiency in all systems, while substituents on the copolymer backbone improved resistance to Ca 2+ . Relevant polymer properties were found to include hydrophobic balance, size and positioning of substituents, rigidity, and electronic effects. The library thus contributes to the rational design of copolymers for the study of MPs.

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“…Although beyond the scope of this work, it should be noted that varying copolymer properties may affect the functionality of membrane proteins. 73 …”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis and Evaluation of a Library of Alternating Amphipathic Copolymers to Solubilize and Study Membrane Proteins

et al. 2022

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“…Additionally, DIBMA is less efficient in solubilizing some of the membrane proteins as compared to SMA, and the stability of DIBMA-based nanodiscs appears to be lower than that of SMA-based nanodiscs [ 162 ]. However, the larger size of DIBMA can be advantageous in accommodating membrane proteins with multiple transmembrane domains (or protein–protein complexes), thus can provide a flexible environment for the protein to be active, as seen in the case of GPCR rhodopsin [ 194 ]. In contrast, SMA- and cationic poly(styrene- co -maleimide) (SMI)-based nanodiscs prevented the conversion of light-activated rhodopsin Meta-I form to the fully active rhodopsin Meta-II form, suggesting that the smaller size nanodiscs and the styrene moiety of the polymers may be restricting protein dynamics or causing an unwanted conformational change.…”

Section: Limitations Of Ionic Polymersmentioning

confidence: 99%

Detergent-Free Isolation of Membrane Proteins and Strategies to Study Them in a Near-Native Membrane Environment

Krishnarjuna

Ramamoorthy

2022

Biomolecules

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Atomic-resolution structural studies of membrane-associated proteins and peptides in a membrane environment are important to fully understand their biological function and the roles played by them in the pathology of many diseases. However, the complexity of the cell membrane has severely limited the application of commonly used biophysical and biochemical techniques. Recent advancements in NMR spectroscopy and cryoEM approaches and the development of novel membrane mimetics have overcome some of the major challenges in this area. For example, the development of a variety of lipid-nanodiscs has enabled stable reconstitution and structural and functional studies of membrane proteins. In particular, the ability of synthetic amphipathic polymers to isolate membrane proteins directly from the cell membrane, along with the associated membrane components such as lipids, without the use of a detergent, has opened new avenues to study the structure and function of membrane proteins using a variety of biophysical and biological approaches. This review article is focused on covering the various polymers and approaches developed and their applications for the functional reconstitution and structural investigation of membrane proteins. The unique advantages and limitations of the use of synthetic polymers are also discussed.

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“…Using this technology, major differences in lipid composition between the central and rim regions of rod outer segment discs were described ( Sander et al, 2021 ). The same methods can be used in vitro to study the impact of changes in lipid bilayer composition on receptor activity ( Grime et al, 2021 ; Szundi et al, 2021 ).…”

Section: Future Directionsmentioning

confidence: 99%

Dynamic Progress in Technological Advances to Study Lipids in Aging: Challenges and Future Directions

2022

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Lipids participate in all cellular processes. Diverse methods have been developed to investigate lipid composition and distribution in biological samples to understand the effect of lipids across an organism’s lifespan. Here, we summarize the advanced techniques for studying lipids, including mass spectrometry-based lipidomics, lipid imaging, chemical-based lipid analysis and lipid engineering and their advantages. We further discuss the limitation of the current methods to gain an in-depth knowledge of the role of lipids in aging, and the possibility of lipid-based therapy in aging-related diseases.

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Differences in SMA-like polymer architecture dictate the conformational changes exhibited by the membrane protein rhodopsin encapsulated in lipid nano-particles

Abstract: Using the GPCR rhodopsin as an exemplar, SMA SMI and DIBMA constitute a ‘tool-kit’ of structurally-related solubilising polymers, with each providing different advantages for studying membrane proteins encapsulated in lipid particles.

Cited by 12 publications

References 49 publications

Synthesis and Evaluation of a Library of Alternating Amphipathic Copolymers to Solubilize and Study Membrane Proteins

Synthesis and Evaluation of a Library of Alternating Amphipathic Copolymers to Solubilize and Study Membrane Proteins

Detergent-Free Isolation of Membrane Proteins and Strategies to Study Them in a Near-Native Membrane Environment

Dynamic Progress in Technological Advances to Study Lipids in Aging: Challenges and Future Directions

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