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van Aalst EJ, Yekefallah M, A M van Beekveld R, Breukink E, Weingarth M, Wylie BJ. Coordination of bilayer properties by an inward-rectifier K + channel is a cooperative process driven by protein-lipid interaction. J Struct Biol X 2024; 9:100101. [PMID: 38883399 PMCID: PMC11176924 DOI: 10.1016/j.yjsbx.2024.100101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 05/27/2024] [Indexed: 06/18/2024] Open
Abstract
Physical properties of biological membranes directly or indirectly govern biological processes. Yet, the interplay between membrane and integral membrane proteins is difficult to assess due to reciprocal effects between membrane proteins, individual lipids, and membrane architecture. Using solid-state NMR (SSNMR) we previously showed that KirBac1.1, a bacterial Inward-Rectifier K+ channel, nucleates bilayer ordering and microdomain formation through tethering anionic lipids. Conversely, these lipids cooperatively bind cationic residues to activate the channel and initiate K+ flux. The mechanistic details governing the relationship between cooperative lipid loading and bilayer ordering are, however, unknown. To investigate, we generated KirBac1.1 samples with different concentrations of 13C-lableded phosphatidyl glycerol (PG) lipids and acquired a full suite of SSNMR 1D temperature series experiments using the ordered all-trans (AT) and disordered trans-gauche (TG) acyl conformations as markers of bilayer dynamics. We observed increased AT ordered signal, decreased TG disordered signal, and increased bilayer melting temperature with increased PG concentration. Further, we identified cooperativity between ordering and direct binding of PG lipids, indicating KirBac1.1-driven bilayer ordering and microdomain formation is a classically cooperative Hill-type process driven by and predicated upon direct binding of PG lipids. Our results provide unique mechanistic insight into how proteins and lipids in tandem contribute to supramolecular bilayer heterogeneity in the lipid membrane.
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Affiliation(s)
- Evan J van Aalst
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Maryam Yekefallah
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Roy A M van Beekveld
- Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Department of Chemistry, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands
| | - Markus Weingarth
- Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands
| | - Benjamin J Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
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Aebischer K, Ernst M. INEPT and CP transfer efficiencies of dynamic systems in MAS solid-state NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 359:107617. [PMID: 38244331 DOI: 10.1016/j.jmr.2024.107617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/22/2024]
Abstract
Hartmann-Hahn cross polarization and INEPT polarization transfer are the most popular sequences to increase the polarization of low-γ nuclei in magic-angle spinning solid-state NMR. It is well known that the two methods preferentially lead to polarization transfer in different parts of molecules. Cross polarization works best in rigid segments of the molecule while INEPT-based polarization transfer is efficient in highly mobile segments where (nearly) isotropic motion averages out the dipolar couplings. However, there have only been few attempts to define the time scales of motion that are compatible with cross polarization or INEPT transfer in a more quantitative way. We have used simple isotropic jump models in combination with simulations based on the stochastic Liouville equation to elucidate the time scales of motion that allow either cross polarization or INEPT-based polarization transfer. We investigate which motional time scales interfere with one or both polarization-transfer schemes. We have modeled isolated I-S two-spin systems, strongly-coupled I2S three-spin systems and more loosely coupled I-I-S three-spin systems as well as I3S groups. Such fragments can be used as models for typical environments in fully deuterated and back-exchanged molecules (I-S), for fully protonated molecules (I2S and I3S) or situations in between (I-I-S).
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Affiliation(s)
- Kathrin Aebischer
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, Zürich, 8093, Switzerland
| | - Matthias Ernst
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, Zürich, 8093, Switzerland.
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Ruiz J, LoRicco JG, Soulère L, Castell MS, Grélard A, Kauffmann B, Dufourc EJ, Demé B, Popowycz F, Peters J. Membrane plasticity induced by myo-inositol derived archaeal lipids: chemical synthesis and biophysical characterization. Phys Chem Chem Phys 2023. [PMID: 37305972 DOI: 10.1039/d3cp01646c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Archaeal membrane lipids have specific structures that allow Archaea to withstand extreme conditions of temperature and pressure. In order to understand the molecular parameters that govern such resistance, the synthesis of 1,2-di-O-phytanyl-sn-glycero-3-phosphoinositol (DoPhPI), an archaeal lipid derived from myo-inositol, is reported. Benzyl protected myo-inositol was first prepared and then transformed to phosphodiester derivatives using a phosphoramidite based-coupling reaction with archaeol. Aqueous dispersions of DoPhPI alone or mixed with DoPhPC can be extruded and form small unilamellar vesicles, as detected by DLS. Neutron, SAXS, and solid-state NMR demonstrated that the water dispersions could form a lamellar phase at room temperature that then evolves into cubic and hexagonal phases with increasing temperature. Phytanyl chains were also found to impart remarkable and nearly constant dynamics to the bilayer over wide temperature ranges. All these new properties of archaeal lipids are proposed as providers of plasticity and thus means for the archaeal membrane to resist extreme conditions.
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Affiliation(s)
- Johal Ruiz
- Univ Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, UMR 5246, CNRS, ICBMS, Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires, Bât. E. Lederer, 1 Rue Victor Grignard, F-69622 Villeurbanne, France
| | | | - Laurent Soulère
- Univ Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, UMR 5246, CNRS, ICBMS, Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires, Bât. E. Lederer, 1 Rue Victor Grignard, F-69622 Villeurbanne, France
| | | | - Axelle Grélard
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France
- Institut Européen de Chimie et Biologie, CNRS, Université de Bordeaux, INSERM, UAR3033, France
| | - Brice Kauffmann
- Institut Européen de Chimie et Biologie, CNRS, Université de Bordeaux, INSERM, UAR3033, France
| | - Erick J Dufourc
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France
- Institut Européen de Chimie et Biologie, CNRS, Université de Bordeaux, INSERM, UAR3033, France
| | - Bruno Demé
- Institut Laue-Langevin, 38000 Grenoble, France.
| | - Florence Popowycz
- Univ Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, UMR 5246, CNRS, ICBMS, Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires, Bât. E. Lederer, 1 Rue Victor Grignard, F-69622 Villeurbanne, France
| | - Judith Peters
- Institut Laue-Langevin, 38000 Grenoble, France.
- Univ. Grenoble Alpes, LiPhy, CNRS, 38000 Grenoble, France
- Institut Universitaire de France, France
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