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Wang DTW, Tang TYC, Kuo CT, Yu YT, Chen EHL, Lee MT, Tsai RF, Chen HY, Chiang YW, Chen RPY. Cholesterol twists the transmembrane Di-Gly region of amyloid-precursor protein. PNAS NEXUS 2023; 2:pgad162. [PMID: 37265546 PMCID: PMC10230161 DOI: 10.1093/pnasnexus/pgad162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 05/08/2023] [Indexed: 06/03/2023]
Abstract
Nearly 95% of Alzheimer's disease (AD) occurs sporadically without genetic linkage. Aging, hypertension, high cholesterol content, and diabetes are known nongenomic risk factors of AD. Aggregation of Aβ peptides is an initial event of AD pathogenesis. Aβ peptides are catabolic products of a type I membrane protein called amyloid precursor protein (APP). Aβ40 is the major product, whereas the 2-residue-longer version, Aβ42, induces amyloid plaque formation in the AD brain. Since cholesterol content is one risk factor for sporadic AD, we aimed to explore whether cholesterol in the membrane affects the structure of the APP transmembrane region, thereby modulating the γ-secretase cutting behavior. Here, we synthesized several peptides containing the APP transmembrane region (sequence 693-726, corresponding to the Aβ22-55 sequence) with one or two Cys mutations for spin labeling. We performed three electron spin resonance experiments to examine the structural changes of the peptides in liposomes composed of dioleoyl phosphatidylcholine and different cholesterol content. Our results show that cholesterol increases membrane thickness by 10% and peptide length accordingly. We identified that the di-glycine region of Aβ36-40 (sequence VGGVV) exhibits the most profound change in response to cholesterol compared with other segments, explaining how the presence of cholesterol affects the γ-secretase cutting site. This study provides spectroscopic evidence showing how cholesterol modulates the structure of the APP transmembrane region in a lipid bilayer.
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Affiliation(s)
- David Tzu-Wei Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Tiffany Y C Tang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Chun-Ting Kuo
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Yun-Ting Yu
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Eric H L Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Ming-Tao Lee
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Department of Physics, National Central University, Zhongli 320317, Taiwan
| | - Ruei-Fong Tsai
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
| | - Hung-Ying Chen
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
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Hao XL, Cao B, Dai D, Wu FG, Yu ZW. Cholesterol Protects the Liquid-Ordered Phase of Raft Model Membranes from the Destructive Effect of Ionic Liquids. J Phys Chem Lett 2022; 13:7386-7391. [PMID: 35925657 DOI: 10.1021/acs.jpclett.2c01873] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ionic liquids (ILs), although being a class of promising green solvents, have received many reports on the toxicity to living organisms. In this work, aiming at elucidating the disruptive effect of ILs to cell membrane lipid rafts, we investigated the effect of three 1-octylimidazolium-based ILs on the properties of the liquid ordered phase (Lo, a commonly used lipid raft model) of egg sphingomyelin (SM)-cholesterol model membrane. We found that, in the absence of cholesterol, a very low IL:SM molar ratio of 0.01:1 could disrupt the integrity of the bilayer structure. In sharp contrast, the presence of cholesterol in lipid bilayers helps the Lo phase resist the damaging effect of the ILs. For the role of the IL headgroup, we found that the mono- and trisubstituted species show a stronger destructive effect on the structures of the model rafts than the commonly used disubstituted counterpart.
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Affiliation(s)
- Xiao-Lei Hao
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Bobo Cao
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Dong Dai
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Fu-Gen Wu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, P. R. China
| | - Zhi-Wu Yu
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
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Callahan KM, Mondou B, Sasseville L, Schwartz JL, D'Avanzo N. The influence of membrane bilayer thickness on KcsA channel activity. Channels (Austin) 2020; 13:424-439. [PMID: 31608774 PMCID: PMC6802934 DOI: 10.1080/19336950.2019.1676367] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Atomic resolution structures have provided significant insight into the gating and permeation mechanisms of various ion channels, including potassium channels. However, ion channels may also be regulated by numerous factors, including the physiochemical properties of the membrane in which they are embedded. For example, the matching of the bilayer's hydrophobic region to the hydrophobic external surface of the ion channel is thought to minimize the energetic penalty needed to solvate hydrophobic residues or exposed lipid tails. To understand the molecular basis of such regulation by hydrophobic matching requires examining channels in the presence of the lipid membrane. Here we examine the role of hydrophobic matching in regulating the activity of the model potassium channel, KcsA. 86Rb+ influx assays and single-channel recordings indicate that the non-inactivating E71A KcsA channel is most active in thin bilayers (<diC18:1PC). Bilayer thickness affects the open probability of KcsA and not its unitary conductance. Molecular dynamics simulations indicate that the bilayer can sufficiently modify its dimensions to accommodate KcsA channels without major perturbations in the protein helical packing within the nanosecond timescale. Based on experimental results and MD simulations, we present a model in which bilayer thickness influences the stability of the open and closed conformations of the intracellular gate of KcsA, with minimal impact on the stability of the selectivity filter of the non-inactivating mutant, E71A.
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Affiliation(s)
- Karen M Callahan
- From the Département de pharmacologie et physiologie, Faculté de médecine, Université de Montréal , Montréal , Canada
| | - Benoit Mondou
- Département de biochimie et médecine moléculaire, Université de Montréal , Montréal , Canada
| | - Louis Sasseville
- From the Département de pharmacologie et physiologie, Faculté de médecine, Université de Montréal , Montréal , Canada
| | - Jean-Louis Schwartz
- From the Département de pharmacologie et physiologie, Faculté de médecine, Université de Montréal , Montréal , Canada.,Département de biochimie et médecine moléculaire, Université de Montréal , Montréal , Canada.,Centre SÈVE, Université de Sherbrooke , Sherbrooke , Canada
| | - Nazzareno D'Avanzo
- From the Département de pharmacologie et physiologie, Faculté de médecine, Université de Montréal , Montréal , Canada.,Département de biochimie et médecine moléculaire, Université de Montréal , Montréal , Canada
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Hsieh MH, Huang PT, Liou HH, Liang PH, Chen PM, Holt SA, Yu IF, James M, Shiau YS, Lee MT, Lin TL, Lou KL. The Penetration Depth for Hanatoxin Partitioning into the Membrane Hydrocarbon Core Measured with Neutron Reflectivity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9036-9046. [PMID: 29986585 DOI: 10.1021/acs.langmuir.8b01076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Hanatoxin (HaTx) from spider venom works as an inhibitor of Kv2.1 channels, most likely by interacting with the voltage sensor (VS). However, the way in which this water-soluble peptide modifies the gating remains poorly understood as the VS is deeply embedded within the bilayer, although it would change its position depending on the membrane potential. To determine whether HaTx can indeed bind to the VS, the depth at which HaTx penetrates into the POPC membranes was measured with neutron reflectivity. Our results successfully demonstrate that HaTx penetrates into the membrane hydrocarbon core (∼9 Å from the membrane surface), not lying on the membrane-water interface as reported for another voltage sensor toxin (VSTx). This difference in penetration depth suggests that the two toxins fix the voltage sensors at different positions with respect to the membrane normal, thereby explaining their different inhibitory effects on the channels. In particular, results from MD simulations constrained by our penetration data clearly demonstrate an appropriate orientation for HaTx to interact with the membranes, which is in line with the biochemical information derived from stopped-flow analysis through delineation of the toxin-VS binding interface.
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Affiliation(s)
- Meng-Hsuan Hsieh
- Membrane Protein Research Core, Center for Biotechnology , National Taiwan University , Taipei 10672 , Taiwan
- Institute of Biotechnology , National Taiwan University , Taipei 10672 , Taiwan
| | - Po-Tsang Huang
- Institute of Biochemistry and Molecular Biology , National Taiwan University , Taipei 10051 , Taiwan
- Graduate Institute of Oral Biology , National Taiwan University , Taipei 10048 , Taiwan
| | - Horng-Huei Liou
- Division of Neurology , National Taiwan University Hospital , Taipei 10002 , Taiwan
| | - Po-Huang Liang
- Institute of Biological Chemistry , Academia Sinica , Taipei 11529 , Taiwan
| | - Pei-Ming Chen
- Department of Electrical Engineering , National Taiwan University , Taipei 10617 , Taiwan
| | - Stephen A Holt
- Australian Centre for Neutron Scattering , Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC , New South Wales , Australia
| | - Isaac Furay Yu
- Department of Chemistry , National Taiwan University , Taipei 10617 , Taiwan
| | - Michael James
- Australian Centre for Neutron Scattering , Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC , New South Wales , Australia
- The Australian Synchrotron , 800 Blackburn Road , Clayton , Victoria 3168 , Australia
| | - Yu-Shuan Shiau
- Membrane Protein Research Core, Center for Biotechnology , National Taiwan University , Taipei 10672 , Taiwan
| | - Ming-Tao Lee
- National Synchrotron Radiation Research Center , Hsinchu 30076 , Taiwan
- Department of Physics , National Central University , Jhongli 32001 , Taiwan
| | - Tsang-Lang Lin
- Department of Engineering and System Science , National Tsing-Hua University , Hsinchu 30013 , Taiwan
| | - Kuo-Long Lou
- Membrane Protein Research Core, Center for Biotechnology , National Taiwan University , Taipei 10672 , Taiwan
- Institute of Biotechnology , National Taiwan University , Taipei 10672 , Taiwan
- Institute of Biochemistry and Molecular Biology , National Taiwan University , Taipei 10051 , Taiwan
- Graduate Institute of Oral Biology , National Taiwan University , Taipei 10048 , Taiwan
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Lee MT. Biophysical characterization of peptide–membrane interactions. ADVANCES IN PHYSICS: X 2018. [DOI: 10.1080/23746149.2017.1408428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Ming-Tao Lee
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
- Department of Physics, National Central University, Jhongli, Taiwan
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