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Qiu Q, Yang M, Gong D, Liang H, Chen T. Potassium and calcium channels in different nerve cells act as therapeutic targets in neurological disorders. Neural Regen Res 2025; 20:1258-1276. [PMID: 38845230 DOI: 10.4103/nrr.nrr-d-23-01766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/07/2024] [Indexed: 07/31/2024] Open
Abstract
The central nervous system, information integration center of the body, is mainly composed of neurons and glial cells. The neuron is one of the most basic and important structural and functional units of the central nervous system, with sensory stimulation and excitation conduction functions. Astrocytes and microglia belong to the glial cell family, which is the main source of cytokines and represents the main defense system of the central nervous system. Nerve cells undergo neurotransmission or gliotransmission, which regulates neuronal activity via the ion channels, receptors, or transporters expressed on nerve cell membranes. Ion channels, composed of large transmembrane proteins, play crucial roles in maintaining nerve cell homeostasis. These channels are also important for control of the membrane potential and in the secretion of neurotransmitters. A variety of cellular functions and life activities, including functional regulation of the central nervous system, the generation and conduction of nerve excitation, the occurrence of receptor potential, heart pulsation, smooth muscle peristalsis, skeletal muscle contraction, and hormone secretion, are closely related to ion channels associated with passive transmembrane transport. Two types of ion channels in the central nervous system, potassium channels and calcium channels, are closely related to various neurological disorders, including Alzheimer's disease, Parkinson's disease, and epilepsy. Accordingly, various drugs that can affect these ion channels have been explored deeply to provide new directions for the treatment of these neurological disorders. In this review, we focus on the functions of potassium and calcium ion channels in different nerve cells and their involvement in neurological disorders such as Parkinson's disease, Alzheimer's disease, depression, epilepsy, autism, and rare disorders. We also describe several clinical drugs that target potassium or calcium channels in nerve cells and could be used to treat these disorders. We concluded that there are few clinical drugs that can improve the pathology these diseases by acting on potassium or calcium ions. Although a few novel ion-channel-specific modulators have been discovered, meaningful therapies have largely not yet been realized. The lack of target-specific drugs, their requirement to cross the blood-brain barrier, and their exact underlying mechanisms all need further attention. This review aims to explain the urgent problems that need research progress and provide comprehensive information aiming to arouse the research community's interest in the development of ion channel-targeting drugs and the identification of new therapeutic targets for that can increase the cure rate of nervous system diseases and reduce the occurrence of adverse reactions in other systems.
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Affiliation(s)
- Qing Qiu
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Inflammation and Molecular Drug Target, Nantong, Jiangsu Province, China
| | - Mengting Yang
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Inflammation and Molecular Drug Target, Nantong, Jiangsu Province, China
| | - Danfeng Gong
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Inflammation and Molecular Drug Target, Nantong, Jiangsu Province, China
| | - Haiying Liang
- Department of Pharmacy, Longyan First Affiliated Hospital of Fujian Medical University, Longyan, Fujian Province, China
| | - Tingting Chen
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Inflammation and Molecular Drug Target, Nantong, Jiangsu Province, China
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2
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Maroli N, Ryan MJ, Zanni MT, Kananenka AA. Do selectivity filter carbonyls in K + channels flip away from the pore? Two-dimensional infrared spectroscopy study. J Struct Biol X 2024; 10:100108. [PMID: 39157159 PMCID: PMC11328031 DOI: 10.1016/j.yjsbx.2024.100108] [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: 03/07/2024] [Revised: 06/26/2024] [Accepted: 07/14/2024] [Indexed: 08/20/2024] Open
Abstract
Molecular dynamics simulations revealed that the carbonyls of the Val residue in the conserved selectivity filter sequence TVGTG of potassium ion channels can flip away from the pore to form hydrogen bonds with the network of water molecules residing behind the selectivity filter. Such a configuration has been proposed to be relevant for C-type inactivation. Experimentally, X-ray crystallography of the KcsA channel admits the possibility that the Val carbonyls can flip, but it cannot decisively confirm the existence of such a configuration. In this study, we combined molecular dynamics simulations and line shape theory to design two-dimensional infrared spectroscopy experiments that can corroborate the existence of the selectivity filter configuration with flipped Val carbonyls. This ability to distinguish between flipped and unflipped carbonyls is based on the varying strength of the electric field inside and outside the pore, which is directly linked to carbonyl stretching frequencies that can be resolved using infrared spectroscopy.
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Affiliation(s)
- Nikhil Maroli
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
| | - Matthew J. Ryan
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Martin T. Zanni
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Alexei A. Kananenka
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
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3
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Olson MA, Han R, Ravula T, Borcik CG, Wang S, Viera PA, Rienstra CM. A complete 3D-printed tool kit for Solid-State NMR sample and rotor handling. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 366:107748. [PMID: 39178738 DOI: 10.1016/j.jmr.2024.107748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 07/31/2024] [Accepted: 08/05/2024] [Indexed: 08/26/2024]
Abstract
Solid state NMR (SSNMR) is a highly versatile and broadly applicable method for studying the structure and dynamics of biomolecules and materials. For scientists entering the field of SSNMR, the many quotidian activities required in the workflow to prepare samples for data collection can present a significant barrier to adoption. These steps include transfer of samples into rotors, marking the reflective surfaces for high sensitivity tachometer signal detection, inserting rotors into the magic-angle spinning (MAS) stator, achieving stable spinning, and removing and storing rotors to ensure reproducibility of data collection conditions. Even experienced spectroscopists experience occasional problems with these operations, and the cumulative probability of a delay to successful data collection is high enough to cause frequent disruptions to instrument schedules, particularly in the context of large facilities serving a diverse community of users. These problems are all amplified when utilizing rotors smaller than about 4 mm in diameter. Therefore, to improve the reliability and robustness of SSNMR sample preparation workflows, here we describe a set of tools for rotor packing, unpacking, tachometer marking, extraction and storage. Stereolithography 3D printing was employed as a cost-effective and convenient method for prototyping and manufacturing a full range of designs suitable for several types of probes and rotor geometries.
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Affiliation(s)
- Martin A Olson
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706 USA
| | - Ruixian Han
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706 USA
| | - Thirupathi Ravula
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706 USA; National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, 53706 USA
| | - Collin G Borcik
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706 USA
| | - Songlin Wang
- National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, 53706 USA
| | - Perla A Viera
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706 USA; Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI, 53706 USA
| | - Chad M Rienstra
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706 USA; Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706 USA; National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, 53706 USA.
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4
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Han R, Borcik CG, Wang S, Warmuth OA, Geohring K, Mullen C, Incitti M, Stringer JA, Rienstra CM. Solid-State NMR 13C sensitivity at high magnetic field. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 365:107709. [PMID: 38991265 DOI: 10.1016/j.jmr.2024.107709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 06/05/2024] [Accepted: 06/06/2024] [Indexed: 07/13/2024]
Abstract
Sensitivity is the foundation of every NMR experiment, and the signal-to-noise ratio (SNR) should increase with static (B0) magnetic field, by a proportionality that primarily depends on the design of the NMR probe and receiver. In the low B0 field limit, where the coil geometry is much smaller than the wavelength of the NMR frequency, SNR can increase in proportion to B0 to the power 7/4. For modern magic-angle spinning (MAS) probes, this approximation holds for rotor sizes up to 3.2 mm at 14.1 Tesla (T), corresponding to 600 MHz 1H and 151 MHz 13C Larmor frequencies. To obtain the anticipated benefit of larger coils and/or higher B0 fields requires a quantitative understanding of the contributions to SNR, utilizing standard samples and protocols that reproduce SNR measurements with high accuracy and precision. Here, we present such a systematic and comprehensive study of 13C SNR under MAS over the range of 14.1 to 21.1 T. We evaluate a range of probe designs utilizing 1.6, 2.5 and 3.2 mm rotors, including 24 different sets of measurements on 17 probe configurations using five spectrometers. We utilize N-acetyl valine as the primary standard and compare and contrast with other commonly used standard samples (adamantane, glycine, hexamethylbenzene, and 3-methylglutaric acid). These robust approaches and standard operating procedures provide an improved understanding of the contributions from probe efficiency, receiver noise figure, and B0 dependence in a range of custom-designed and commercially available probes. We find that the optimal raw SNR is obtained with balanced 3.2 mm design at 17.6 T, that the best mass-limited SNR is achieved with a balanced 1.6 mm design at 21.1 T, and that the raw SNR at 21.1 T reaches diminishing returns with rotors larger than 2.5 mm.
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Affiliation(s)
- Ruixian Han
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, United States
| | - Collin G Borcik
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, United States
| | - Songlin Wang
- National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, United States
| | - Owen A Warmuth
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, United States
| | | | | | | | | | - Chad M Rienstra
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, United States; Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, United States; National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, United States.
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5
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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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6
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Yekefallah M, van Aalst EJ, van Beekveld RAM, Eason IR, Breukink E, Weingarth M, Wylie BJ. Cooperative Gating of a K + Channel by Unmodified Biological Anionic Lipids Viewed by Solid-State NMR Spectroscopy. J Am Chem Soc 2024; 146:4421-4432. [PMID: 38334076 PMCID: PMC10885140 DOI: 10.1021/jacs.3c09266] [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: 08/24/2023] [Revised: 01/23/2024] [Accepted: 01/24/2024] [Indexed: 02/10/2024]
Abstract
Lipids adhere to membrane proteins to stimulate or suppress molecular and ionic transport and signal transduction. Yet, the molecular details of lipid-protein interaction and their functional impact are poorly characterized. Here we combine NMR, coarse-grained molecular dynamics (CGMD), and functional assays to reveal classic cooperativity in the binding and subsequent activation of a bacterial inward rectifier potassium (Kir) channel by phosphatidylglycerol (PG), a common component of many membranes. Past studies of lipid activation of Kir channels focused primarily on phosphatidylinositol bisphosphate, a relatively rare signaling lipid that is tightly regulated in space and time. We use solid-state NMR to quantify the binding of unmodified 13C-PG to the K+ channel KirBac1.1 in liposomes. This specific lipid-protein interaction has a dissociation constant (Kd) of ∼7 mol percentage PG (ΧPG) with positive cooperativity (n = 3.8) and approaches saturation near 20% ΧPG. Liposomal flux assays show that K+ flux also increases with PG in a cooperative manner with an EC50 of ∼20% ΧPG, within the physiological range. Further quantitative fitting of these data reveals that PG acts as a partial (80%) agonist with fivefold K+ flux amplification. Comparisons of NMR chemical shift perturbation and CGMD simulations at different ΧPG confirm the direct interaction of PG with key residues, several of which would not be accessible to lipid headgroups in the closed state of the channel. Allosteric regulation by a common lipid is directly relevant to the activation mechanisms of several human ion channels. This study highlights the role of concentration-dependent lipid-protein interactions and tightly controlled protein allostery in the activation and regulation of ion channels.
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Affiliation(s)
- Maryam Yekefallah
- Department
of Chemistry and Biochemistry, Texas Tech
University, Lubbock, Texas 79409, United States
| | - Evan J. van Aalst
- Department
of Chemistry and Biochemistry, Texas Tech
University, Lubbock, Texas 79409, United States
| | - Roy A. M. van Beekveld
- Department
of Chemistry, Faculty of Science, Utrecht
University, Padualaan 8, Utrecht3584
CH, The Netherlands
| | - Isaac R. Eason
- Department
of Chemistry and Biochemistry, Texas Tech
University, Lubbock, Texas 79409, United States
| | - Eefjan Breukink
- Membrane
Biochemistry and Biophysics, Department of Chemistry, Utrecht University, Padualaan 8, Utrecht 3584
CH, The Netherlands
| | - Markus Weingarth
- Department
of Chemistry, Faculty of Science, Utrecht
University, Padualaan 8, Utrecht3584
CH, The Netherlands
| | - Benjamin J. Wylie
- Department
of Chemistry and Biochemistry, Texas Tech
University, Lubbock, Texas 79409, United States
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7
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Mitra K, Krishnan Y. Lightly counting membrane proteins in native nanodiscs. NATURE NANOTECHNOLOGY 2024; 19:5-6. [PMID: 38012272 DOI: 10.1038/s41565-023-01538-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Affiliation(s)
- Koushambi Mitra
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Neuroscience Institute, The University of Chicago, Chicago, IL, USA
- Institute of Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
| | - Yamuna Krishnan
- Department of Chemistry, The University of Chicago, Chicago, IL, USA.
- Neuroscience Institute, The University of Chicago, Chicago, IL, USA.
- Institute of Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.
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8
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Ryan M, Gao L, Valiyaveetil FI, Zanni MT, Kananenka AA. Probing Ion Configurations in the KcsA Selectivity Filter with Single-Isotope Labels and 2D IR Spectroscopy. J Am Chem Soc 2023; 145:18529-18537. [PMID: 37578394 PMCID: PMC10450685 DOI: 10.1021/jacs.3c05339] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Indexed: 08/15/2023]
Abstract
The potassium ion (K+) configurations of the selectivity filter of the KcsA ion channel protein are investigated with two-dimensional infrared (2D IR) spectroscopy of amide I vibrations. Single 13C-18O isotope labels are used, for the first time, to selectively probe the S1/S2 or S2/S3 binding sites in the selectivity filter. These binding sites have the largest differences in ion occupancy in two competing K+ transport mechanisms: soft-knock and hard-knock. According to the former, water molecules alternate between K+ ions in the selectivity filter while the latter assumes that K+ ions occupy the adjacent sites. Molecular dynamics simulations and computational spectroscopy are employed to interpret experimental 2D IR spectra. We find that in the closed conductive state of the KcsA channel, K+ ions do not occupy adjacent binding sites. The experimental data is consistent with simulated 2D IR spectra of soft-knock ion configurations. In contrast, the simulated spectra for the hard-knock ion configurations do not reproduce the experimental results. 2D IR spectra of the hard-knock mechanism have lower frequencies, homogeneous 2D lineshapes, and multiple peaks. In contrast, ion configurations of the soft-knock model produce 2D IR spectra with a single peak at a higher frequency and inhomogeneous lineshape. We conclude that under equilibrium conditions, in the absence of transmembrane voltage, both water and K+ ions occupy the selectivity filter of the KcsA channel in the closed conductive state. The ion configuration is central to the mechanism of ion transport through potassium channels.
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Affiliation(s)
- Matthew
J. Ryan
- Department
of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Lujia Gao
- Department
of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - Francis I. Valiyaveetil
- Department
of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - Martin T. Zanni
- Department
of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Alexei A. Kananenka
- Department
of Physics and Astronomy, University of
Delaware, Newark, Delaware 19716, United States
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9
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van Aalst EJ, Jang J, Halligan TC, Wylie BJ. Strategies for acquisition of resonance assignment spectra of highly dynamic membrane proteins: a GPCR case study. JOURNAL OF BIOMOLECULAR NMR 2023; 77:191-202. [PMID: 37493866 PMCID: PMC10838152 DOI: 10.1007/s10858-023-00421-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 07/11/2023] [Indexed: 07/27/2023]
Abstract
In protein nuclear magnetic resonance (NMR), chemical shift assignment provides a wealth of information. However, acquisition of high-quality solid-state NMR spectra depends on protein-specific dynamics. For membrane proteins, bilayer heterogeneity further complicates this observation. Since the efficiency of cross-polarization transfer is strongly entwined with protein dynamics, optimal temperatures for spectral sensitivity and resolution will depend not only on inherent protein dynamics, but temperature-dependent phase properties of the bilayer environment. We acquired 1-, 2-, and 3D homo- and heteronuclear experiments of the chemokine receptor CCR3 in a 7:3 phosphatidylcholine:cholesterol lipid environment. 1D direct polarization, cross polarization (CP), and T2' experiments indicate sample temperatures below - 25 °C facilitate higher CP enhancement and longer-lived transverse relaxation times. T1rho experiments indicate intermediate timescales are minimized below a sample temperature of - 20 °C. 2D DCP NCA experiments indicated optimal CP efficiency and resolution at a sample temperature of - 30 °C, corroborated by linewidth analysis in 3D NCACX at - 30 °C compared to - 5 °C. This optimal temperature is concluded to be directly related the lipid phase transition, measured to be between - 20 and 15 °C based on rINEPT signal of all-trans and trans-gauche lipid acyl conformations. Our results have critical implications in acquisition of SSNMR membrane protein assignment spectra, as we hypothesize that different lipid compositions with different phase transition properties influence protein dynamics and therefore the optimal acquisition temperature.
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Affiliation(s)
- Evan J van Aalst
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79415, USA
| | - Jun Jang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79415, USA
| | - Ty C Halligan
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79415, USA
| | - Benjamin J Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79415, USA.
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10
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Zhu P, Kong L, Zhang Y, Liu Q, Liao X, Song Y, Yang B. Synthetic transmembrane channel molecules formed by acyclic cucurbiturils and pillararene: tuning cation selectivity and generating membrane potential. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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11
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Yekefallah M, Rasberry CA, van Aalst EJ, Browning HP, Amani R, Versteeg DB, Wylie BJ. Mutational Insight into Allosteric Regulation of Kir Channel Activity. ACS OMEGA 2022; 7:43621-43634. [PMID: 36506180 PMCID: PMC9730464 DOI: 10.1021/acsomega.2c04456] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 11/10/2022] [Indexed: 06/08/2023]
Abstract
Potassium (K+) channels are regulated in part by allosteric communication between the helical bundle crossing, or inner gate, and the selectivity filter, or outer gate. This network is triggered by gating stimuli. In concert, there is an allosteric network which is a conjugated set of interactions which correlate long-range structural rearrangements necessary for channel function. Inward-rectifier K+ (Kir) channels favor inward K+ conductance, are ligand-gated, and help establish resting membrane potentials. KirBac1.1 is a bacterial Kir (KirBac) channel homologous to human Kir (hKir) channels. Additionally, KirBac1.1 is gated by the anionic phospholipid ligand phosphatidylglycerol (PG). In this study, we use site-directed mutagenesis to investigate residues involved in the KirBac1.1 gating mechanism and allosteric network we previously proposed using detailed solid-state NMR (SSNMR) measurements. Using fluorescence-based K+ and sodium (Na+) flux assays, we identified channel mutants with impaired function that do not alter selectivity of the channel. In tandem, we performed coarse grain molecular dynamics simulations, observing changes in PG-KirBac1.1 interactions correlated with mutant channel activity and contacts between the two transmembrane helices and pore helix tied to this behavior. Lipid affinity is closely tied to the proximity of two tryptophan residues on neighboring subunits which lure anionic lipids to a cationic pocket formed by a cluster of arginine residues. Thus, these simulations establish a structural and functional basis for the role of each mutated site in the proposed allosteric network. The experimental and simulated data provide insight into key functional residues involved in gating and lipid allostery of K+ channels. Our findings also have direct implications on the physiology of hKir channels due to conservation of many of the residues identified in this work from KirBac1.1.
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12
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van Aalst EJ, Borcik CG, Wylie BJ. Spectroscopic signatures of bilayer ordering in native biological membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183891. [PMID: 35217001 PMCID: PMC10793244 DOI: 10.1016/j.bbamem.2022.183891] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Membrane proteins and polycyclic lipids like cholesterol and hopanoids coordinate phospholipid bilayer ordering. This phenomenon manifests as partitioning of the liquid crystalline phase into liquid-ordered (Lo) and liquid-disordered (Ld) regions. In Eukaryotes, microdomains are rich in cholesterol and sphingolipids and serve as signal transduction scaffolds. In Prokaryotes, Lo microdomains increase pathogenicity and antimicrobial resistance. Previously, we identified spectroscopically distinct chemical shift signatures for all-trans (AT) and trans-gauche (TG) acyl chain conformations, cyclopropyl ring lipids (CPR), and hopanoids in prokaryotic lipid extracts and used Polarization Transfer (PT) SSNMR to investigate bilayer ordering. To investigate how these findings relate to native bilayer organization, we interrogate whole cell and whole membrane extract samples of Burkholderia thailendensis to investigate bilayer ordering in situ. In 13C-13C 2D SSNMR spectra, we assigned chemical shifts for lipid species in both samples, showing conservation of lipids of interest in our native membrane sample. A one-dimensional temperature series of PT SSNMR and transverse relaxation measurements of AT versus TG acyl conformations in the membrane sample confirm bilayer ordering and a broadened phase transition centered at a lower-than-expected temperature. Bulk protein backbone Cα dynamics and correlations consistent with lipid-protein contacts within are further indicative of microdomain formation and lipid ordering. In aggregate, these findings provide evidence for microdomain formation in vivo and provide insight into phase separation and transition mechanics in biological membranes.
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Affiliation(s)
- Evan J van Aalst
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79415, USA
| | - Collin G Borcik
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79415, USA
| | - Benjamin J Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79415, USA.
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13
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Borcik CG, Eason IR, Yekefallah M, Amani R, Han R, Vanderloop BH, Wylie BJ. A Cholesterol Dimer Stabilizes the Inactivated State of an Inward-Rectifier Potassium Channel. Angew Chem Int Ed Engl 2022; 61:e202112232. [PMID: 34985791 PMCID: PMC8957755 DOI: 10.1002/anie.202112232] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Indexed: 12/15/2022]
Abstract
Cholesterol oligomers reside in multiple membrane protein X-ray crystal structures. Yet, there is no direct link between these oligomers and a biological function. Here we present the structural and functional details of a cholesterol dimer that stabilizes the inactivated state of an inward-rectifier potassium channel KirBac1.1. K+ efflux assays confirm that high cholesterol concentration reduces K+ conductance. We then determine the structure of the cholesterol-KirBac1.1 complex using Xplor-NIH simulated annealing calculations driven by solid-state NMR distance measurements. These calculations identified an α-α cholesterol dimer docked to a cleft formed by adjacent subunits of the homotetrameric protein. We compare these results to coarse grain molecular dynamics simulations. This is one of the first examples of a cholesterol oligomer performing a distinct biological function and structural characterization of a conserved promiscuous lipid binding region.
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Affiliation(s)
- Collin G Borcik
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Isaac R Eason
- 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
| | - Reza Amani
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Ruixian Han
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Boden H Vanderloop
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Benjamin J Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
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14
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Wang Y, Zhang X, Wang S, Li Z, Hu X, Yang X, Song Y, Jing Y, Hu Q, Ni Y. Identification of Metabolism-Associated Biomarkers for Early and Precise Diagnosis of Oral Squamous Cell Carcinoma. Biomolecules 2022; 12:biom12030400. [PMID: 35327590 PMCID: PMC8945702 DOI: 10.3390/biom12030400] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 02/23/2022] [Accepted: 02/23/2022] [Indexed: 01/27/2023] Open
Abstract
The 5-year survival rate for oral squamous cell carcinoma (OSCC), one of the most common head and neck cancers, has not improved in the last 20 years. Poor prognosis of OSCC is the result of failure in early and precise diagnosis. Metabolic reprogramming, including the alteration of the uptake and utilisation of glucose, amino acids and lipids, is an important feature of OSCC and can be used to identify its biomarkers for early and precise diagnosis. In this review, we summarise how recent findings of rewired metabolic networks in OSCC have facilitated early and precise diagnosis of OSCC.
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Affiliation(s)
- Yuhan Wang
- Central Laboratory of Stomatology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210008, China; (Y.W.); (X.Z.); (S.W.); (Z.L.); (X.H.); (Y.S.); (Y.J.)
| | - Xiaoxin Zhang
- Central Laboratory of Stomatology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210008, China; (Y.W.); (X.Z.); (S.W.); (Z.L.); (X.H.); (Y.S.); (Y.J.)
| | - Shuai Wang
- Central Laboratory of Stomatology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210008, China; (Y.W.); (X.Z.); (S.W.); (Z.L.); (X.H.); (Y.S.); (Y.J.)
| | - Zihui Li
- Central Laboratory of Stomatology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210008, China; (Y.W.); (X.Z.); (S.W.); (Z.L.); (X.H.); (Y.S.); (Y.J.)
| | - Xinyang Hu
- Central Laboratory of Stomatology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210008, China; (Y.W.); (X.Z.); (S.W.); (Z.L.); (X.H.); (Y.S.); (Y.J.)
| | - Xihu Yang
- Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Jiangsu University, Zhenjiang 210008, China;
| | - Yuxian Song
- Central Laboratory of Stomatology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210008, China; (Y.W.); (X.Z.); (S.W.); (Z.L.); (X.H.); (Y.S.); (Y.J.)
| | - Yue Jing
- Central Laboratory of Stomatology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210008, China; (Y.W.); (X.Z.); (S.W.); (Z.L.); (X.H.); (Y.S.); (Y.J.)
| | - Qingang Hu
- Department of Oral and Maxillofacial Surgery, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210008, China
- Correspondence: (Q.H.); (Y.N.)
| | - Yanhong Ni
- Central Laboratory of Stomatology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210008, China; (Y.W.); (X.Z.); (S.W.); (Z.L.); (X.H.); (Y.S.); (Y.J.)
- Correspondence: (Q.H.); (Y.N.)
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15
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Borcik CG, Eason IR, Yekefallah M, Amani R, Han R, Vanderloop BH, Wylie BJ. A Cholesterol Dimer Stabilizes the Inactivated State of an Inward‐Rectifier Potassium Channel. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202112232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Collin G. Borcik
- Department of Chemistry and Biochemistry Texas Tech University Lubbock TX 79409 USA
| | - Isaac R. Eason
- 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
| | - Reza Amani
- Department of Chemistry and Biochemistry Texas Tech University Lubbock TX 79409 USA
| | - Ruixian Han
- Department of Biochemistry University of Wisconsin-Madison Madison WI 53706 USA
| | - Boden H. Vanderloop
- Department of Chemistry and Biochemistry Texas Tech University Lubbock TX 79409 USA
| | - Benjamin J. Wylie
- Department of Chemistry and Biochemistry Texas Tech University Lubbock TX 79409 USA
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16
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Amani R, Schwieters CD, Borcik CG, Eason IR, Han R, Harding BD, Wylie BJ. Water Accessibility Refinement of the Extended Structure of KirBac1.1 in the Closed State. Front Mol Biosci 2021; 8:772855. [PMID: 34917650 PMCID: PMC8669819 DOI: 10.3389/fmolb.2021.772855] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 11/08/2021] [Indexed: 11/17/2022] Open
Abstract
NMR structures of membrane proteins are often hampered by poor chemical shift dispersion and internal dynamics which limit resolved distance restraints. However, the ordering and topology of these systems can be defined with site-specific water or lipid proximity. Membrane protein water accessibility surface area is often investigated as a topological function via solid-state NMR. Here we leverage water-edited solid-state NMR measurements in simulated annealing calculations to refine a membrane protein structure. This is demonstrated on the inward rectifier K+ channel KirBac1.1 found in Burkholderia pseudomallei. KirBac1.1 is homologous to human Kir channels, sharing a nearly identical fold. Like many existing Kir channel crystal structures, the 1p7b crystal structure is incomplete, missing 85 out of 333 residues, including the N-terminus and C-terminus. We measure solid-state NMR water proximity information and use this for refinement of KirBac1.1 using the Xplor-NIH structure determination program. Along with predicted dihedral angles and sparse intra- and inter-subunit distances, we refined the residues 1-300 to atomic resolution. All structural quality metrics indicate these restraints are a powerful way forward to solve high quality structures of membrane proteins using NMR.
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Affiliation(s)
- Reza Amani
- Texas Tech University, Department of Chemistry and Biochemistry, Lubbock, TX, United States
| | - Charles D. Schwieters
- Computational Biomolecular Magnetic Resonance Core, National Institutes of Digestive Diseases and Kidneys, NIH, Bethesda, MD, United States
| | - Collin G. Borcik
- Texas Tech University, Department of Chemistry and Biochemistry, Lubbock, TX, United States
| | - Isaac R. Eason
- Texas Tech University, Department of Chemistry and Biochemistry, Lubbock, TX, United States
| | - Ruixian Han
- University of Wisconsin-Madison, Department of Biochemistry and Chemistry, Madison, WI, United States
| | - Benjamin D. Harding
- University of Wisconsin-Madison, Department of Biochemistry and Chemistry, Madison, WI, United States
- Biophysics Program, University of Wisconsin at Madison, Madison, WI, United States
| | - Benjamin J. Wylie
- Texas Tech University, Department of Chemistry and Biochemistry, Lubbock, TX, United States
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17
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van Aalst E, Wylie BJ. Cholesterol Is a Dose-Dependent Positive Allosteric Modulator of CCR3 Ligand Affinity and G Protein Coupling. Front Mol Biosci 2021; 8:724603. [PMID: 34490352 PMCID: PMC8417553 DOI: 10.3389/fmolb.2021.724603] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 07/14/2021] [Indexed: 01/14/2023] Open
Abstract
Cholesterol as an allosteric modulator of G protein-coupled receptor (GPCR) function is well documented. This quintessential mammalian lipid facilitates receptor–ligand interactions and multimerization states. Functionally, this introduces a complicated mechanism for the homeostatic modulation of GPCR signaling. Chemokine receptors are Class A GPCRs responsible for immune cell trafficking through the binding of endogenous peptide ligands. CCR3 is a CC motif chemokine receptor expressed by eosinophils and basophils. It traffics these cells by transducing the signal stimulated by the CC motif chemokine primary messengers 11, 24, and 26. These behaviors are close to the human immunoresponse. Thus, CCR3 is implicated in cancer metastasis and inflammatory conditions. However, there is a paucity of experimental evidence linking the functional states of CCR3 to the molecular mechanisms of cholesterol–receptor cooperativity. In this vein, we present a means to combine codon harmonization and a maltose-binding protein fusion tag to produce CCR3 from E. coli. This technique yields ∼2.6 mg of functional GPCR per liter of minimal media. We leveraged this protein production capability to investigate the effects of cholesterol on CCR3 function in vitro. We found that affinity for the endogenous ligand CCL11 increases in a dose-dependent manner with cholesterol concentration in both styrene:maleic acid lipid particles (SMALPs) and proteoliposomes. This heightened receptor activation directly translates to increased signal transduction as measured by the GTPase activity of the bound G-protein α inhibitory subunit 3 (Gαi3). This work represents a critical step forward in understanding the role of cholesterol-GPCR allostery in regulation of signal transduction.
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Affiliation(s)
- Evan van Aalst
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, United States
| | - Benjamin J Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, United States
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18
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Mironenko A, Zachariae U, de Groot BL, Kopec W. The Persistent Question of Potassium Channel Permeation Mechanisms. J Mol Biol 2021; 433:167002. [PMID: 33891905 DOI: 10.1016/j.jmb.2021.167002] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/14/2021] [Accepted: 04/15/2021] [Indexed: 02/09/2023]
Abstract
Potassium channels play critical roles in many physiological processes, providing a selective permeation route for K+ ions in and out of a cell, by employing a carefully designed selectivity filter, evolutionarily conserved from viruses to mammals. The structure of the selectivity filter was determined at atomic resolution by x-ray crystallography, showing a tight coordination of desolvated K+ ions by the channel. However, the molecular mechanism of K+ ions permeation through potassium channels remains unclear, with structural, functional and computational studies often providing conflicting data and interpretations. In this review, we will present the proposed mechanisms, discuss their origins, and will critically assess them against all available data. General properties shared by all potassium channels are introduced first, followed by the introduction of two main mechanisms of ion permeation: soft and direct knock-on. Then, we will discuss critical computational and experimental studies that shaped the field. We will especially focus on molecular dynamics (MD) simulations, that provided mechanistic and energetic aspects of K+ permeation, but at the same time created long-standing controversies. Further challenges and possible solutions are presented as well.
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Affiliation(s)
- Andrei Mironenko
- Computational Biomolecular Dynamics Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Bert L de Groot
- Computational Biomolecular Dynamics Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Wojciech Kopec
- Computational Biomolecular Dynamics Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
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