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Keating PM, Schifano NP, Wei X, Kong MY, Lee J. pH-dependent conformational change within the Lassa virus transmembrane domain elicits efficient membrane fusion. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184233. [PMID: 37734457 DOI: 10.1016/j.bbamem.2023.184233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/05/2023] [Accepted: 09/16/2023] [Indexed: 09/23/2023]
Abstract
Lassa virus (LASV) is the most prevalent member of the arenavirus family and the causative agent of Lassa fever, a viral hemorrhagic fever. Although there are annual outbreaks in West Africa, and recently isolated cases worldwide, there are no current therapeutics or vaccines, which poses LASV as a significant global public health threat. One of the key steps in LASV infection is the delivery of its genetic material by fusing its viral membrane with the host cell membrane. This process is facilitated by significant conformational changes within glycoprotein 2 (GP2), yielding distinct prefusion and postfusion structural states. However, structural information is missing to understand the changes that occur in the transmembrane domain during the fusion process. Here, we used CD and NMR spectroscopy to show that the transmembrane domain has pH-dependent conformational changes that result in an extension of the alpha helix at the N-terminal end. Proline mutants of key residues in that region prevent the helical extension, as seen in CD and NMR. We developed a modified lipid mixing assay to study the importance of this extension on the function of GP2. Our assay shows that membrane fusion efficiency is optimal at low pH values but introducing the proline mutants results in lower fusion efficiency. These results indicate that these pH-dependent conformational changes are important to the fusion mechanism. This information can be used to design therapeutics to combat Lassa virus infections and prevent its potential spread.
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Affiliation(s)
- Patrick M Keating
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Nicholas P Schifano
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Xinrui Wei
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Matthew Y Kong
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Jinwoo Lee
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
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2
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Michalski M, Setny P. Molecular Mechanisms behind Conformational Transitions of the Influenza Virus Hemagglutinin Membrane Anchor. J Phys Chem B 2023; 127:9450-9460. [PMID: 37877534 PMCID: PMC10641832 DOI: 10.1021/acs.jpcb.3c05257] [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: 08/03/2023] [Revised: 10/06/2023] [Accepted: 10/09/2023] [Indexed: 10/26/2023]
Abstract
Membrane fusion is a fundamental process that is exploited by enveloped viruses to enter host cells. In the case of the influenza virus, fusion is facilitated by the trimeric viral hemagglutinin protein (HA). So far, major focus has been put on its N-terminal fusion peptides, which are directly responsible for fusion initiation. A growing body of evidence points also to a significant functional role of the HA C-terminal domain, which however remains incompletely understood. Our computational study aimed to elucidate the structural and functional interdependencies within the HA C-terminal region encompassing the transmembrane domain (TMD) and the cytoplasmic tail (CT). In particular, we were interested in the conformational shift of the TMD in response to varying cholesterol concentration in the viral membrane and in its modulation by the presence of CT. Using free-energy calculations based on atomistic molecular dynamics simulations, we characterized transitions between straight and tilted metastable TMD configurations under varying conditions. We found that the presence of CT is essential for achieving a stable, highly tilted TMD configuration. As we demonstrate, such a configuration of HA membrane anchor likely supports the tilting motion of its ectodomain, which needs to be executed during membrane fusion. This finding highlights the functional role of, so far, the relatively overlooked CT region.
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Affiliation(s)
- Michal Michalski
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Piotr Setny
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
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3
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Miao X, Yin Y, Chen Y, Bi W, Yin Y, Chen S, Peng D, Gao L, Qin T, Liu X. Bidirectionally Regulating Viral and Cellular Ferroptosis with Metastable Iron Sulfide Against Influenza Virus. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023:e2206869. [PMID: 37092591 DOI: 10.1002/advs.202206869] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 03/29/2023] [Indexed: 05/03/2023]
Abstract
Influenza virus with numerous subtypes and frequent variation limits the development of high-efficacy and broad-spectrum antiviral strategy. Here, a novel multi-antiviral metastable iron sulfides (mFeS) against various influenza A/B subtype viruses is developed. This work finds that mFeS induces high levels of lipid peroxidation and •OH free radicals in the conservative viral envelope, which depends on Fe2+ . This phenomenon, termed as a viral ferroptosis, results in the loss of viral infectibility and pathogenicity in vitro and in vivo, respectively. Furthermore, the decoction of mFeS (Dc(mFeS)) inhibits cellular ferroptosis-dependent intracellular viral replication by correcting the virus-induced reprogrammed sulfur metabolism, a conserved cellular metabolism. Notably, personal protective equipment (PPE) that is loaded with mFeS provides good antiviral protection. Aerosol administration of mFeS combined with the decoction (mFeS&Dc) has a potential therapeutic effect against H1N1 lethal infection in mice. Collectively, mFeS represents an antiviral alternative with broad-spectrum activity against intracellular and extracellular influenza virus.
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Affiliation(s)
- Xinyu Miao
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
| | - Yinyan Yin
- College of Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- Guangling College, Yangzhou University, Yangzhou, Jiangsu, 225000, P. R. China
| | - Yulian Chen
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
| | - Wenhui Bi
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
| | - Yuncong Yin
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
| | - Sujuan Chen
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
| | - Daxin Peng
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- Jiangsu Research Centre of Engineering and Technology for Prevention and Control of Poultry Disease, Yangzhou, Jiangsu, 225009, P. R. China
| | - Lizeng Gao
- CAS Engineering Laboratory for Nanozyme, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, P. R. China
| | - Tao Qin
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- Jiangsu Research Centre of Engineering and Technology for Prevention and Control of Poultry Disease, Yangzhou, Jiangsu, 225009, P. R. China
| | - Xiufan Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu, 225009, P. R. China
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4
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Surmeier G, Dogan-Surmeier S, Paulus M, Albers C, Latarius J, Sternemann C, Schneider E, Tolan M, Nase J. The interaction of viral fusion peptides with lipid membranes. Biophys J 2022; 121:3811-3825. [PMID: 36110043 PMCID: PMC9674987 DOI: 10.1016/j.bpj.2022.09.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/13/2022] [Accepted: 09/12/2022] [Indexed: 11/02/2022] Open
Abstract
In this paper, we studied fusogenic peptides of class I-III fusion proteins, which are relevant to membrane fusion for certain enveloped viruses, in contact with model lipid membranes. We resolved the vertical structure and examined the adsorption or penetration behavior of the fusogenic peptides at phospholipid Langmuir monolayers with different initial surface pressures with x-ray reflectometry. We show that the fusion loops of tick-borne encephalitis virus (TBEV) glycoprotein E and vesicular stomatitis virus (VSV) G-protein are not able to insert deeply into model lipid membranes, as they adsorbed mainly underneath the headgroups with only limited penetration depths into the lipid films. In contrast, we observed that the hemagglutinin 2 fusion peptide (HA2-FP) and the VSV-transmembrane domain (VSV-TMD) can penetrate deeply into the membranes. However, in the case of VSV-TMD, the penetration was suppressed already at low surface pressures, whereas HA2-FP was able to insert even into highly compressed films. Membrane fusion is accompanied by drastic changes of the membrane curvature. To investigate how the peptides affect the curvature of model lipid membranes, we examined the effect of the fusogenic peptides on the equilibration of cubic monoolein structures after a phase transition from a lamellar state induced by an abrupt hydrostatic pressure reduction. We monitored this process in presence and absence of the peptides with small-angle x-ray scattering and found that HA2-FP and VSV-TMD drastically accelerate the equilibration, while the fusion loops of TBEV and VSV stabilize the swollen state of the lipid structures. In this work, we show that the class I fusion peptide of HA2 penetrates deeply into the hydrophobic region of membranes and is able to promote and accelerate the formation of negative curvature. In contrast, we found that the class II and III fusion loops of TBEV and VSV tend to counteract negative membrane curvature.
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Affiliation(s)
- Göran Surmeier
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | | | - Michael Paulus
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | - Christian Albers
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | - Jan Latarius
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | | | - Eric Schneider
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | - Metin Tolan
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | - Julia Nase
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
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Daniels RS, Galiano M, Ermetal B, Kwong J, Lau CS, Xiang Z, McCauley JW, Lo J. Temporal and Gene Reassortment Analysis of Influenza C Virus Outbreaks in Hong Kong, SAR, China. J Virol 2022; 96:e0192821. [PMID: 34787455 PMCID: PMC8826914 DOI: 10.1128/jvi.01928-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 11/09/2021] [Indexed: 11/29/2022] Open
Abstract
From 2014 to week 07/2020 the Centre for Health Protection in Hong Kong conducted screening for influenza C virus (ICV). A retrospective analysis of ICV detections to week 26/2019 revealed persistent low-level circulation with outbreaks occurring biennially in the winters of 2015 to 2016 and 2017 to 2018 (R. S. Daniels et al., J Virol 94:e01051-20, 2020, https://doi.org/10.1128/JVI.01051-20). Here, we report on an outbreak occurring in 2019 to 2020, reinforcing the observation of biennial seasonality in Hong Kong. All three outbreaks occurred in similar time frames, were subsequently dwarfed by seasonal epidemics of influenza types A and B, and were caused by similar proportions of C/Kanagawa/1/76 (K)-lineage and C/São Paulo/378/82 S1- and S2-sublineage viruses. Ongoing genetic drift was observed in all genes, with some evidence of amino acid substitution in the hemagglutinin-esterase-fusion (HEF) glycoprotein possibly associated with antigenic drift. A total of 61 ICV genomes covering the three outbreaks were analyzed for reassortment, and 9 different reassortant constellations were identified, 1 K-lineage, 4 S1-sublineage, and 4 S2-sublineage, with 6 of these being identified first in the 2019-1920 outbreak (2 S2-lineage and 4 S1-lineage). The roles that virus interference/enhancement, ICV persistent infection, genome evolution, and reassortment might play in the observed seasonality of ICV in Hong Kong are discussed. IMPORTANCE Influenza C virus (ICV) infection of humans is common, with the great majority of people being infected during childhood, though reinfection can occur throughout life. While infection normally results in "cold-like" symptoms, severe disease cases have been reported in recent years. However, knowledge of ICV is limited due to poor systematic surveillance and an inability to propagate the virus in large amounts in the laboratory. Following recent systematic surveillance in Hong Kong SAR, China, and direct ICV gene sequencing from clinical specimens, a 2-year cycle of disease outbreaks (epidemics) has been identified, with gene mixing playing a significant role in ICV evolution. Studies like those reported here are key to developing an understanding of the impact of influenza C virus infection in humans, notably where comorbidities exist and severe respiratory disease can develop.
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Affiliation(s)
- Rodney S. Daniels
- Worldwide Influenza Centre, The Francis Crick Institute, London, United Kingdom
| | - Monica Galiano
- Worldwide Influenza Centre, The Francis Crick Institute, London, United Kingdom
| | - Burcu Ermetal
- Worldwide Influenza Centre, The Francis Crick Institute, London, United Kingdom
| | - Jasmine Kwong
- Centre for Health Protection, Department of Health, Hong Kong SAR, China
| | - Chi S. Lau
- Centre for Health Protection, Department of Health, Hong Kong SAR, China
| | - Zheng Xiang
- Worldwide Influenza Centre, The Francis Crick Institute, London, United Kingdom
| | - John W. McCauley
- Worldwide Influenza Centre, The Francis Crick Institute, London, United Kingdom
| | - Janice Lo
- Centre for Health Protection, Department of Health, Hong Kong SAR, China
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Park JH, Mohapatra A, Zhou J, Holay M, Krishnan N, Gao W, Fang RH, Zhang L. Virus‐Mimicking Cell Membrane‐Coated Nanoparticles for Cytosolic Delivery of mRNA. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202113671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Joon Ho Park
- Department of NanoEngineering Chemical Engineering Program Moores Cancer Center University of California San Diego La Jolla CA 92093 USA
| | - Animesh Mohapatra
- Department of NanoEngineering Chemical Engineering Program Moores Cancer Center University of California San Diego La Jolla CA 92093 USA
| | - Jiarong Zhou
- Department of NanoEngineering Chemical Engineering Program Moores Cancer Center University of California San Diego La Jolla CA 92093 USA
| | - Maya Holay
- Department of NanoEngineering Chemical Engineering Program Moores Cancer Center University of California San Diego La Jolla CA 92093 USA
| | - Nishta Krishnan
- Department of NanoEngineering Chemical Engineering Program Moores Cancer Center University of California San Diego La Jolla CA 92093 USA
| | - Weiwei Gao
- Department of NanoEngineering Chemical Engineering Program Moores Cancer Center University of California San Diego La Jolla CA 92093 USA
| | - Ronnie H. Fang
- Department of NanoEngineering Chemical Engineering Program Moores Cancer Center University of California San Diego La Jolla CA 92093 USA
| | - Liangfang Zhang
- Department of NanoEngineering Chemical Engineering Program Moores Cancer Center University of California San Diego La Jolla CA 92093 USA
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7
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Park JH, Mohapatra A, Zhou J, Holay M, Krishnan N, Gao W, Fang RH, Zhang L. Virus-Mimicking Cell Membrane-Coated Nanoparticles for Cytosolic Delivery of mRNA. Angew Chem Int Ed Engl 2022; 61:e202113671. [PMID: 34694684 PMCID: PMC8727555 DOI: 10.1002/anie.202113671] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Indexed: 01/12/2023]
Abstract
Effective endosomal escape after cellular uptake represents a major challenge in the field of nanodelivery, as the majority of drug payloads must localize to subcellular compartments other than the endosomes in order to exert activity. In nature, viruses can readily deliver their genetic material to the cytosol of host cells by triggering membrane fusion after endocytosis. For the influenza A virus, the hemagglutinin (HA) protein found on its surface fuses the viral envelope with the surrounding membrane at endosomal pH values. Biomimetic nanoparticles capable of endosomal escape were fabricated using a membrane coating derived from cells engineered to express HA on their surface. When evaluated in vitro, these virus-mimicking nanoparticles were able to deliver an mRNA payload to the cytosolic compartment of target cells, resulting in the successful expression of the encoded protein. When the mRNA-loaded nanoparticles were administered in vivo, protein expression levels were significantly increased in both local and systemic delivery scenarios. We therefore conclude that utilizing genetic engineering approaches to express viral fusion proteins on the surface of cell membrane-coated nanoparticles is a viable strategy for modulating the intracellular localization of encapsulated cargoes.
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Affiliation(s)
| | | | | | | | | | | | - Ronnie H. Fang
- Department of NanoEngineering, Chemical Engineering Program, and Moores Cancer Center, University of California San Diego, La Jolla, CA 92093 (USA)
| | - Liangfang Zhang
- Department of NanoEngineering, Chemical Engineering Program, and Moores Cancer Center, University of California San Diego, La Jolla, CA 92093 (USA)
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Petrich A, Dunsing V, Bobone S, Chiantia S. Influenza A M2 recruits M1 to the plasma membrane: A fluorescence fluctuation microscopy study. Biophys J 2021; 120:5478-5490. [PMID: 34808098 PMCID: PMC8715234 DOI: 10.1016/j.bpj.2021.11.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 10/16/2021] [Accepted: 11/17/2021] [Indexed: 11/17/2022] Open
Abstract
Influenza A virus (IAV) is a respiratory pathogen that causes seasonal epidemics with significant mortality. One of the most abundant proteins in IAV particles is the matrix protein 1 (M1), which is essential for the virus structural stability. M1 organizes virion assembly and budding at the plasma membrane (PM), where it interacts with other viral components. The recruitment of M1 to the PM as well as its interaction with the other viral envelope proteins (hemagglutinin [HA], neuraminidase, matrix protein 2 [M2]) is controversially discussed in previous studies. Therefore, we used fluorescence fluctuation microscopy techniques (i.e., scanning fluorescence cross-correlation spectroscopy and number and brightness) to quantify the oligomeric state of M1 and its interactions with other viral proteins in co-transfected as well as infected cells. Our results indicate that M1 is recruited to the PM by M2, as a consequence of the strong interaction between the two proteins. In contrast, only a weak interaction between M1 and HA was observed. M1-HA interaction occurred only in the event that M1 was already bound to the PM. We therefore conclude that M2 initiates the assembly of IAV by recruiting M1 to the PM, possibly allowing its further interaction with other viral proteins.
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Affiliation(s)
- Annett Petrich
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Valentin Dunsing
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Sara Bobone
- University of Rome Tor Vergata, Department of Chemical Science and Technologies, Roma, Italy
| | - Salvatore Chiantia
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany.
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Khrustalev VV, Kordyukova LV, Arutyunyan AM, Poboinev VV, Khrustaleva TA, Stojarov AN, Baratova LA, Sapon AS, Lugin VG. The cytoplasmic tail of influenza A/H1N1 virus hemagglutinin is β-structural. J Biomol Struct Dyn 2020; 40:4642-4661. [PMID: 33317396 DOI: 10.1080/07391102.2020.1860827] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Influenza A/H1N1 virus hemagglutinin (HA) is an integral type I glycoprotein that contains a large glycosylated ectodomain, a transmembrane domain, and a cytoplasmic tail (CT) of 10-14 amino acid residues. There are absolutely no data on the secondary or tertiary structure of the HA CT, which is important for virus pathogenesis. Three highly conserved cysteines are post-translationally modified by the attachment of fatty acid residues that pin the CT to the lipid membrane inside the virion. We applied circular dichroism (CD) and fluorescence spectroscopy analysis to examine four synthetic peptides corresponding to 14-15 C-terminal residues of H1 subtype HA (NH2-WMCSNGSLQCRICI-COOH; NH2-FWMCSNGSLQCRICI-COOH), with free or acetaminomethylated cysteines, in the reduced or non-reduced state, at various pH values and temperatures. The CD analysis detected the formation of a β-structure (30-65% according to the new BeStSel algorithm), in addition to an unstructured random coil, in every peptide in various conditions. It was completely or partially recognized as an antiparallel β-structure that was also confirmed by the multi-bounce Horizontal Attenuated Total Reflectance Fourier Transformed Infrared (HATR-FTIR) spectroscopy analysis. According to the experimental data, as well as 3 D modeling, we assume that the amino acid sequence corresponding to the HA CT may form a short antiparallel β-structure under the lipid membrane within a virion.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
| | - Larisa V Kordyukova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Alexander M Arutyunyan
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Victor V Poboinev
- Department of General Chemistry, Belarusian State Medical University, Minsk, Belarus
| | - Tatyana A Khrustaleva
- Biochemical group of the Multidisciplinary Diagnostic Laboratory, Institute of Physiology of the National Academy of Sciences of Belarus, Minsk, Belarus
| | - Aleksander N Stojarov
- Department of Radiation Medicine and Ecology, Belarusian State Medical University, Minsk, Belarus
| | - Lyudmila A Baratova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Alena S Sapon
- Center for Physical and Chemical Research Methods, Belarusian State Technological University, Minsk, Belarus
| | - Valery G Lugin
- Center for Physical and Chemical Research Methods, Belarusian State Technological University, Minsk, Belarus
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Wu J, Wang Y, Wei Y, Xu Z, Tan X, Wu Z, Zheng J, Liu GD, Cao Y, Xue C. Disulfide isomerase ERp57 improves the stability and immunogenicity of H3N2 influenza virus hemagglutinin. Virol J 2020; 17:55. [PMID: 32316996 PMCID: PMC7175539 DOI: 10.1186/s12985-020-01325-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/08/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Hemagglutinin (HA), as the surface immunogenic protein, is the most important component of influenza viruses. Previous studies showed that the stability of HA was significant for HA's immunogenicity, and many efforts have been made to stabilize the expressed HA proteins. METHODS In this study, the protein disulfide isomerases (PDIs) were investigated for the ability to improve the stability of HA protein. Two members of the PDIs family, PDI and ERp57, were over-expressed or down-expressed in 293 T cells. The expression of H3 HA and PDIs were investigated by real-time qPCR, western-blot, immunofluorescence assay, and flow cytometry. The stability of HA was investigated by western-blot under non-reducing condition. Moreover, BALB/c mice were immunized subcutaneously twice with the vaccine that contained HA proteins from the ERp57-overexpressed and conventional 293 T cells respectively to investigate the impact of ERp57 on the immunogenicity of H3N2 HA. RESULTS The percentage of the disulfide-bonded HA trimers increased significantly in the PDIs-overexpressed 293 T cells, and ERp57 was more valid to the stability of HA than PDI. The knockdown of ERp57 by small interfering RNA significantly decreased the percentage of the disulfide-bonded HA trimers. HA proteins from ERp57-overexpressed 293 T cells stimulated the mice to generate significantly higher HA-specific IgG against H1N1 and H3N2 viruses than those from the conventional cells. The mice receiving H3 HA from ERp57-overexpressed 293 T cells showed the better resistance against H1N1 viruses and the higher survival rate than the mice receiving H3 HA from the conventional cells. CONCLUSION ERp57 could improve the stability and immunogenicity of H3N2 HA.
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Affiliation(s)
- Jialing Wu
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, China.,Clinical Research Institute, The First People's Hospital of Foshan, Foshan, 528000, China
| | - Yang Wang
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, China
| | - Ying Wei
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, China
| | - Zhichao Xu
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, China
| | - Xin Tan
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, China
| | - Zhihui Wu
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, China
| | - Jing Zheng
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, China
| | - George Dacai Liu
- Firstline Biopharmaceuticals Corporation, 12050 167th PL NE, Redmond, WA, 98052, USA
| | - Yongchang Cao
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, China
| | - Chunyi Xue
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, 510006, China.
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11
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Pitjamit S, Thunsiri K, Nakkiew W, Wongwichai T, Pothacharoen P, Wattanutchariya W. The Possibility of Interlocking Nail Fabrication from FFF 3D Printing PLA/PCL/HA Composites Coated by Local Silk Fibroin for Canine Bone Fracture Treatment. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E1564. [PMID: 32231063 PMCID: PMC7177625 DOI: 10.3390/ma13071564] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/21/2020] [Accepted: 03/26/2020] [Indexed: 12/11/2022]
Abstract
The biomaterials polylactic acid (PLA), polycaprolactone (PCL), and hydroxyapatite (HA) were selected to fabricate composite filaments for 3D printing fused filament fabrication (FFF), which was used to fabricate a composite biomaterial for an interlocking nail for canine diaphyseal fractures instead of metal bioinert materials. Bioactive materials were used to increase biological activities and provide a high possibility for bone regeneration to eliminate the limitations of interlocking nails. HA was added to PLA and PCL granules in three ratios according to the percentage of HA: 0%, 5%, and 15% (PLA/PCL, PLA/PCL/5HA, and PLA/PCL/15HA, respectively), before the filaments were extruded. The test specimens were 3D-printed from the extruded composite filaments using an FFF printer. Then, a group of test specimens was coated by silk fibroin (SF) using the lyophilization technique to increase their biological properties. Mechanical, biological, and chemical characterizations were performed to investigate the properties of the composite biomaterials. The glass transition and melting temperatures of the copolymer were not influenced by the presence of HA in the PLA/PCL filaments. Meanwhile, the presence of HA in the PLA/PCL/15HA group resulted in the highest compressive strength (82.72 ± 1.76 MPa) and the lowest tensile strength (52.05 ± 2.44 MPa). HA provided higher bone cell proliferation, and higher values were observed in the SF coating group. Therefore, FFF 3D-printed filaments using composite materials with bioactive materials have a high potential for use in fabricating an interlocking nail for canine diaphyseal fractures.
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Affiliation(s)
- Siwasit Pitjamit
- Department of Industrial Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand;
- Advanced Manufacturing Technology Research Center (AMTech), Department of Industrial Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.); (W.W.)
| | - Kittiya Thunsiri
- Advanced Manufacturing Technology Research Center (AMTech), Department of Industrial Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.); (W.W.)
- Biomedical Engineering Institute, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Wasawat Nakkiew
- Advanced Manufacturing Technology Research Center (AMTech), Department of Industrial Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.); (W.W.)
| | - Tunchanok Wongwichai
- Thailand Excellence Center for Tissue Engineering and Stem Cell, Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand; (T.W.); (P.P.)
| | - Peraphan Pothacharoen
- Thailand Excellence Center for Tissue Engineering and Stem Cell, Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand; (T.W.); (P.P.)
| | - Wassanai Wattanutchariya
- Advanced Manufacturing Technology Research Center (AMTech), Department of Industrial Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.); (W.W.)
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12
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Cholesterol Binding to the Transmembrane Region of a Group 2 Hemagglutinin (HA) of Influenza Virus Is Essential for Virus Replication, Affecting both Virus Assembly and HA Fusion Activity. J Virol 2019; 93:JVI.00555-19. [PMID: 31118253 DOI: 10.1128/jvi.00555-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 05/14/2019] [Indexed: 12/21/2022] Open
Abstract
Hemagglutinin (HA) of influenza virus is incorporated into cholesterol-enriched nanodomains of the plasma membrane. Phylogenetic group 2 HAs contain the conserved cholesterol consensus motif (CCM) YKLW in the transmembrane region. We previously reported that mutations in the CCM retarded intracellular transport of HA and decreased its nanodomain association. Here, we analyzed whether cholesterol interacts with the CCM. Incorporation of photocholesterol into HA was significantly reduced if the whole CCM is replaced by alanine, both using immunoprecipitated HA and when HA is embedded in the membrane. We next used reverse genetics to investigate the significance of the CCM for virus replication. No virus was rescued if the whole motif is exchanged (YKLW4A); singly (LA) or doubly (YK2A and LW2A) mutated virus showed decreased titers and a comparative fitness disadvantage. In polarized cells, transport of HA mutants to the apical membrane was not disturbed. Reduced amounts of HA and cholesterol were incorporated into the viral membrane. Mutant viruses exhibit a decrease in hemolysis, which is only partially corrected if the membrane is replenished with cholesterol. More specifically, viruses have a defect in hemifusion, as demonstrated by fluorescence dequenching. Cells expressing HA YKLW4A fuse with erythrocytes, but the number of events is reduced. Even after acidification unfused erythrocytes remain cell bound, a phenomenon not observed with wild-type HA. We conclude that cholesterol binding to a group 2 HA is essential for virus replication. It has pleiotropic effects on virus assembly and membrane fusion, mainly on lipid mixing and possibly a preceding step.IMPORTANCE The glycoprotein HA is a major pathogenicity factor of influenza viruses. Whereas the structure and function of HA's ectodomain is known in great detail, similar data for the membrane-anchoring part of the protein are missing. Here, we demonstrate that the transmembrane region of a group 2 HA interacts with cholesterol, the major lipid of the plasma membrane and the defining element of the viral budding site nanodomains of the plasma membrane. The cholesterol binding motif is essential for virus replication. Its partial removal affects various steps of the viral life cycle, such as assembly of new virus particles and their subsequent cell entry via membrane fusion. A cholesterol binding pocket in group 2 HAs might be a promising target for a small lipophilic drug that inactivates the virus.
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13
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Ranaweera A, Ratnayake PU, Ekanayaka EAP, Declercq R, Weliky DP. Hydrogen-Deuterium Exchange Supports Independent Membrane-Interfacial Fusion Peptide and Transmembrane Domains in Subunit 2 of Influenza Virus Hemagglutinin Protein, a Structured and Aqueous-Protected Connection between the Fusion Peptide and Soluble Ectodomain, and the Importance of Membrane Apposition by the Trimer-of-Hairpins Structure. Biochemistry 2019; 58:2432-2446. [PMID: 31008587 DOI: 10.1021/acs.biochem.8b01272] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The influenza virus hemagglutinin (HA) protein has HA1 and HA2 subunits, which form an initial complex. HA1's bind host cell sialic acids, which triggers endocytosis, HA1/HA2 separation, and HA2-mediated fusion between virus and endosome membranes. We report hydrogen-deuterium exchange mass spectrometry (HDX-MS) on the HA2 subunit without HA1. HA2 contains the fusion peptide (FP), soluble ectodomain (SE), transmembrane domain (TM), and endodomain. FP is a monomer by itself, while SE is a trimer of hairpins that includes an interior bundle of residue 38-105 helices, turns, and residue 154-178 strands packed antiparallel to the bundle. FP and TM extend from the same side of the SE hairpin, and fusion models often depict a FP/TM complex with membrane traversal of both domains that is important for membrane pore expansion. The HDX-MS data of this study do not support this complex and instead support independent FP and TM with respective membrane-interfacial and traversal locations. The data also show a low level of aqueous exposure of the 22-38 segment, consistent with retention of the 23-35 antiparallel β sheet observed in the initial HA1/HA2 complex. We propose the β sheet as a semirigid connector between FP and SE that enables close membrane apposition prior to fusion. The I173E mutant exhibits greater exchange for residues 22-69 and 150-191, consistent with dissociation of SE C-terminal strands from interior N-helices. Similar trends are observed for the G1E mutant as well as less exchange for G1E FP. Fusion is highly impaired with either mutant, which correlates with reduced membrane apposition and, for G1E, FP binding to SE rather than the target membrane.
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Affiliation(s)
- Ahinsa Ranaweera
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Punsisi U Ratnayake
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - E A Prabodha Ekanayaka
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Robin Declercq
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - David P Weliky
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
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14
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Abstract
Fourier transform infrared (FTIR) spectroscopy has become one of the major techniques of structural characterization of proteins, peptides, and protein-membrane interactions. While the method does not have the capability of providing the precise, atomic-resolution molecular structure, it is exquisitely sensitive to conformational changes occurring in proteins upon functional transitions or intermolecular interactions. The sensitivity of vibrational frequencies to atomic masses has led to development of "isotope-edited" FTIR spectroscopy, where structural effects in two proteins, one unlabeled and the other labeled with a heavier stable isotope, such as 13C, are resolved simultaneously based on spectral downshift (separation) of the amide I band of the labeled protein. The same isotope effect is used to identify site-specific conformational changes in proteins by site-directed or segmental isotope labeling. Negligible light scattering in the infrared region provides an opportunity to study intermolecular interactions between large protein complexes, interactions of proteins and peptides with lipid vesicles, or protein-nucleic acid interactions without light scattering problems often encountered in ultraviolet spectroscopy. Attenuated total reflection FTIR (ATR-FTIR) is a surface-sensitive version of infrared spectroscopy that has proved useful in studying membrane proteins and lipids, protein-membrane interactions, mechanisms of interfacial enzymes, the structural features of membrane pore forming proteins and peptides, and much more. The purpose of this chapter was to provide a practical guide to analyze protein structure and protein-membrane interactions by FTIR and ATR-FTIR techniques, including procedures of sample preparation, measurements, and data analysis. Basic background information on FTIR spectroscopy, as well as some relatively new developments in structural and functional characterization of proteins and peptides in lipid membranes, is also presented.
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Affiliation(s)
- Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, FL, USA.
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15
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Ranaweera A, Ratnayake PU, Weliky DP. The Stabilities of the Soluble Ectodomain and Fusion Peptide Hairpins of the Influenza Virus Hemagglutinin Subunit II Protein Are Positively Correlated with Membrane Fusion. Biochemistry 2018; 57:5480-5493. [PMID: 30141905 DOI: 10.1021/acs.biochem.8b00764] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cellular entry of influenza virus is mediated by the viral protein hemagglutinin (HA), which forms an initial complex of three HA1 and three HA2 subunits. Each HA2 includes a fusion peptide (FP), a soluble ectodomain (SE), and a transmembrane domain. HA1 binds to cellular sialic acids, followed by virus endocytosis, pH reduction, dissociation of HA1, and structural rearrangement of HA2 into a final trimer-of-SE hairpins. A decrease in pH also triggers HA2-mediated virus/endosome membrane fusion. SE hairpins have an interior parallel helical bundle and C-terminal strands in the grooves of the exterior of the bundle. FPs are separate helical hairpins. This study compares wild-type HA2 (WT-HA2) with G1E(FP) and I173E(SE strand) mutants. WT-HA2 induces vesicle fusion at pH 5.0, whereas the extent of fusion is greatly reduced for both mutants. Circular dichroism for HA2 and FHA2≡FP+SE constructs shows dramatic losses of stability for the mutants, including a Tm reduced by 40 °C for I173E-FHA2. This is evidence of destabilization of SE hairpins via dissociation of strands from the helical bundle, which is also supported by larger monomer fractions for mutant versus WT proteins. The G1E mutant may have disrupted FP hairpins, with consequent non-native FP binding to dissociated SE strands. It is commonly proposed that free energy released by the HA2 structural rearrangement catalyzes HA-mediated fusion. This study supports an alternate mechanistic model in which fusion is preceded by FP insertion in the target membrane and formation of the final SE hairpin. Less fusion by the mutants is due to the loss of hairpin stability and consequent reduced level of membrane apposition of the virus and target membranes.
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Affiliation(s)
- Ahinsa Ranaweera
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Punsisi U Ratnayake
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
| | - David P Weliky
- Department of Chemistry , Michigan State University , East Lansing , Michigan 48824 , United States
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16
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Chipot C, Dehez F, Schnell JR, Zitzmann N, Pebay-Peyroula E, Catoire LJ, Miroux B, Kunji ERS, Veglia G, Cross TA, Schanda P. Perturbations of Native Membrane Protein Structure in Alkyl Phosphocholine Detergents: A Critical Assessment of NMR and Biophysical Studies. Chem Rev 2018; 118:3559-3607. [PMID: 29488756 PMCID: PMC5896743 DOI: 10.1021/acs.chemrev.7b00570] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Indexed: 12/25/2022]
Abstract
Membrane proteins perform a host of vital cellular functions. Deciphering the molecular mechanisms whereby they fulfill these functions requires detailed biophysical and structural investigations. Detergents have proven pivotal to extract the protein from its native surroundings. Yet, they provide a milieu that departs significantly from that of the biological membrane, to the extent that the structure, the dynamics, and the interactions of membrane proteins in detergents may considerably vary, as compared to the native environment. Understanding the impact of detergents on membrane proteins is, therefore, crucial to assess the biological relevance of results obtained in detergents. Here, we review the strengths and weaknesses of alkyl phosphocholines (or foscholines), the most widely used detergent in solution-NMR studies of membrane proteins. While this class of detergents is often successful for membrane protein solubilization, a growing list of examples points to destabilizing and denaturing properties, in particular for α-helical membrane proteins. Our comprehensive analysis stresses the importance of stringent controls when working with this class of detergents and when analyzing the structure and dynamics of membrane proteins in alkyl phosphocholine detergents.
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Affiliation(s)
- Christophe Chipot
- SRSMC, UMR 7019 Université de Lorraine CNRS, Vandoeuvre-les-Nancy F-54500, France
- Laboratoire
International Associé CNRS and University of Illinois at Urbana−Champaign, Vandoeuvre-les-Nancy F-54506, France
- Department
of Physics, University of Illinois at Urbana−Champaign, 1110 West Green Street, Urbana, Illinois 61801, United States
| | - François Dehez
- SRSMC, UMR 7019 Université de Lorraine CNRS, Vandoeuvre-les-Nancy F-54500, France
- Laboratoire
International Associé CNRS and University of Illinois at Urbana−Champaign, Vandoeuvre-les-Nancy F-54506, France
| | - Jason R. Schnell
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Nicole Zitzmann
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | | | - Laurent J. Catoire
- Laboratory
of Biology and Physico-Chemistry of Membrane Proteins, Institut de Biologie Physico-Chimique (IBPC), UMR
7099 CNRS, Paris 75005, France
- University
Paris Diderot, Paris 75005, France
- PSL
Research University, Paris 75005, France
| | - Bruno Miroux
- Laboratory
of Biology and Physico-Chemistry of Membrane Proteins, Institut de Biologie Physico-Chimique (IBPC), UMR
7099 CNRS, Paris 75005, France
- University
Paris Diderot, Paris 75005, France
- PSL
Research University, Paris 75005, France
| | - Edmund R. S. Kunji
- Medical
Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Gianluigi Veglia
- Department
of Biochemistry, Molecular Biology, and Biophysics, and Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Timothy A. Cross
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Paul Schanda
- Université
Grenoble Alpes, CEA, CNRS, IBS, Grenoble F-38000, France
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17
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Young-Speirs M, Drouin D, Cavalcante PA, Barkema HW, Cobo ER. Host defense cathelicidins in cattle: types, production, bioactive functions and potential therapeutic and diagnostic applications. Int J Antimicrob Agents 2018; 51:813-821. [PMID: 29476808 DOI: 10.1016/j.ijantimicag.2018.02.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 02/07/2018] [Accepted: 02/11/2018] [Indexed: 12/22/2022]
Abstract
Cathelicidins are a primitive class of host defense peptides and are known for their broad-spectrum antimicrobial activity against bacteria, fungi, and enveloped viruses. These small, cationic, proteolytically-activated peptides are diverse in structure, encompassing a wide range of activities on host immune and inflammatory cell responses. The dual capacity of cathelicidins to directly control infection and regulate host defenses highlights the potential use of these peptides as alternatives to antibiotics and immunomodulators. Cathelicidins are found in many mammalian species; this review focuses on bovine cathelicidins. Eight naturally and two synthetically occurring bovine cathelicidins are described in detail, with a focus on recent advances in their expression, location and biological roles. This review also presents an overview of the bioactive functions of cathelicidins in bovine mastitis, a disease causing economic losses in cattle dairy production. Comparison of the structural, antimicrobial, cytotoxic and mechanistic properties of bovine cathelicidins advances the knowledge needed for the development of these peptides as potential identifiers of infectious diseases (e.g., bovine mastitis) and as novel therapeutic alternatives to antibiotics.
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Affiliation(s)
- Morgan Young-Speirs
- Bachelor of Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Dominique Drouin
- Bachelor of Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Paloma Araujo Cavalcante
- Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Herman W Barkema
- Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Eduardo R Cobo
- Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.
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18
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Structure of the Ebola virus envelope protein MPER/TM domain and its interaction with the fusion loop explains their fusion activity. Proc Natl Acad Sci U S A 2017; 114:E7987-E7996. [PMID: 28874543 DOI: 10.1073/pnas.1708052114] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Ebolavirus (EBOV), an enveloped filamentous RNA virus causing severe hemorrhagic fever, enters cells by macropinocytosis and membrane fusion in a late endosomal compartment. Fusion is mediated by the EBOV envelope glycoprotein GP, which consists of subunits GP1 and GP2. GP1 binds to cellular receptors, including Niemann-Pick C1 (NPC1) protein, and GP2 is responsible for low pH-induced membrane fusion. Proteolytic cleavage and NPC1 binding at endosomal pH lead to conformational rearrangements of GP2 that include exposing the hydrophobic fusion loop (FL) for insertion into the cellular target membrane and forming a six-helix bundle structure. Although major portions of the GP2 structure have been solved in pre- and postfusion states and although current models place the transmembrane (TM) and FL domains of GP2 in close proximity at critical steps of membrane fusion, their structures in membrane environments, and especially interactions between them, have not yet been characterized. Here, we present the structure of the membrane proximal external region (MPER) connected to the TM domain: i.e., the missing parts of the EBOV GP2 structure. The structure, solved by solution NMR and EPR spectroscopy in membrane-mimetic environments, consists of a helix-turn-helix architecture that is independent of pH. Moreover, the MPER region is shown to interact in the membrane interface with the previously determined structure of the EBOV FL through several critical aromatic residues. Mutation of aromatic and neighboring residues in both binding partners decreases fusion and viral entry, highlighting the functional importance of the MPER/TM-FL interaction in EBOV entry and fusion.
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19
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Kordyukova L. Structural and functional specificity of Influenza virus haemagglutinin and paramyxovirus fusion protein anchoring peptides. Virus Res 2017; 227:183-199. [DOI: 10.1016/j.virusres.2016.09.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 09/21/2016] [Accepted: 09/23/2016] [Indexed: 02/08/2023]
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20
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Worch R, Krupa J, Filipek A, Szymaniec A, Setny P. Three conserved C-terminal residues of influenza fusion peptide alter its behavior at the membrane interface. Biochim Biophys Acta Gen Subj 2016; 1861:97-105. [PMID: 27825831 DOI: 10.1016/j.bbagen.2016.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 10/24/2016] [Accepted: 11/03/2016] [Indexed: 11/18/2022]
Abstract
The N-terminal fragment of the viral hemagglutinin HA2 subunit is termed a fusion peptide (HAfp). The 23-amino acid peptide (HAfp1-23) contains three C-terminal W21-Y22-G23 residues which are highly conserved among serotypes of influenza A and has been shown to form a tight helical hairpin very distinct from the boomerang structure of HAfp1-20. We studied the effect of peptide length on fusion properties, structural dynamics, and binding to the membrane interface. We developed a novel fusion visualization assay based on FLIM microscopy on giant unilamellar vesicles (GUV). By means of molecular dynamics simulations and spectroscopic measurements, we show that the presence of the three C-terminal W21-Y22-G23 residues promotes the hairpin formation, which orients perpendicularly to the membrane plane and induces more disorder in the surrounding lipids than the less structured HAfp1-20. Moreover, we report cholesterol-enriched domain formation induced exclusively by the longer fusion peptide.
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Affiliation(s)
| | - Joanna Krupa
- Institute of Physics, Polish Academy of Sciences, Poland
| | - Alicja Filipek
- Institute of Physics, Polish Academy of Sciences, Poland
| | - Anna Szymaniec
- Institute of Physics, Polish Academy of Sciences, Poland
| | - Piotr Setny
- Centre for New Technologies, University of Warsaw, Poland
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21
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Goldblatt G, Matos JO, Gornto J, Tatulian SA. Isotope-edited FTIR reveals distinct aggregation and structural behaviors of unmodified and pyroglutamylated amyloid β peptides. Phys Chem Chem Phys 2016. [PMID: 26214017 DOI: 10.1039/c5cp03343h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Amyloid β peptide (Aβ) is causatively associated with Alzheimer's disease (AD), and N-terminally truncated and pyroglutamylated Aβ peptides (AβpE) exert hypertoxic effect by an unknown mechanism. Recent evidence has identified the prefibrillar oligomers of Aβ, not the fibrils, as the prevalent cytotoxic species. Structural characterization of Aβ and AβpE oligomers is therefore important for better understanding of their toxic effect. Here we have used isotope-edited Fourier transform infrared (FTIR) spectroscopy to identify the conformational changes in Aβ(1-42) and AβpE(3-42) upon aggregation, individually and in 1 : 1 molar combination. During the first two hours of exposure to aqueous buffer, the peptides undergo transition from mostly α-helical to mostly β-sheet structure. Data on peptides (13)C,(15)N-labeled at K(16)L(17)V(18) or V(36)G(37)G(38)V(39) allowed construction of structural models for the monomer and early oligomers. The peptide monomer comprises a β-hairpin that involves residues upstream of the K(16)L(17)V(18) sequence and an N-terminal α-helix. The oligomers form by non-H-bonding interactions between the β-strands of neighboring β-hairpins, in lateral or staggered manner, with the strands running parallel or antiparallel. Relative α-helical and β-sheet propensities of Aβ(1-42) and AβpE(3-42) depend on the ionic strength of the buffer, emphasizing the importance of ionic interactions in Aβ peptide structure and aggregation. It is inferred that N-terminal modification of AβpE(3-42) affects the helix stability and thereby modulates β-sheet oligomer formation. The data thus provide new insight into the molecular mechanism of Aβ oligomerization by emphasizing the role of the N-terminal transient α-helical structure and by identifying structural constraints for molecular organization of the oligomers.
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Affiliation(s)
- Greg Goldblatt
- Biomedical Sciences Graduate Program, University of Central Florida, Orlando, FL, USA
| | - Jason O Matos
- Biotechnology Graduate Program, University of Central Florida, Orlando, FL, USA
| | - Jeremy Gornto
- Undergraduate student, University of Central Florida, Orlando, FL, USA
| | - Suren A Tatulian
- Department of Physics, Physical Sciences Room 456, University of Central Florida, 4111 Libra Drive, Orlando, Florida 32816-2385, USA.
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22
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Lai AL, Freed JH. The Interaction between Influenza HA Fusion Peptide and Transmembrane Domain Affects Membrane Structure. Biophys J 2015; 109:2523-2536. [PMID: 26682811 PMCID: PMC4699882 DOI: 10.1016/j.bpj.2015.10.044] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 10/05/2015] [Accepted: 10/27/2015] [Indexed: 11/27/2022] Open
Abstract
Viral glycoproteins, such as influenza hemagglutinin (HA) and human immunodeficiency virus gp41, are anchored by a single helical segment transmembrane domain (TMD) on the viral envelope membrane. The fusion peptides (FP) of the glycoproteins insert into the host membrane and initiate membrane fusion. Our previous study showed that the FP or TMD alone perturbs membrane structure. Interaction between the influenza HA FP and TMD has previously been shown, but its role is unclear. We used PC spin labels dipalmitoylphospatidyl-tempo-choline (on the headgroup), 5PC and 14PC (5-C and 14-C positions on the acyl chain) to detect the combined effect of FP-TMD interaction by titrating HA FP to TMD-reconstituted 1,2-dimyristoyl-sn-glycero-3-phosphocholine/1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol)/cholesterol lipid bilayers using electron spin resonance. We found that the FP-TMD increases the lipid order at all positions, which has a greater lipid ordering effect than the sum of the FP or TMD alone, and this effect reaches deeper into the membranes. Although HA-mediated membrane fusion is pH dependent, this combined effect is observed at both pH 5 and pH 7. In addition to increasing lipid order, multiple components are found for 5PC at increased concentration of FP-TMD, indicating that distinct domains are induced. However, the mutation of Gly1 in the FP and L187 in the TMD eliminates the perturbations, consistent with their fusogenic phenotypes. Electron spin resonance on spin-labeled peptides confirms these observations. We suggest that this interaction may provide a driving force in different stages of membrane fusion: initialization, transition from hemifusion stalk to transmembrane contact, and fusion pore formation.
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Affiliation(s)
- Alex L Lai
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York
| | - Jack H Freed
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York.
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23
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Viral fusion protein transmembrane domain adopts β-strand structure to facilitate membrane topological changes for virus-cell fusion. Proc Natl Acad Sci U S A 2015; 112:10926-31. [PMID: 26283363 DOI: 10.1073/pnas.1501430112] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The C-terminal transmembrane domain (TMD) of viral fusion proteins such as HIV gp41 and influenza hemagglutinin (HA) is traditionally viewed as a passive α-helical anchor of the protein to the virus envelope during its merger with the cell membrane. The conformation, dynamics, and lipid interaction of these fusion protein TMDs have so far eluded high-resolution structure characterization because of their highly hydrophobic nature. Using magic-angle-spinning solid-state NMR spectroscopy, we show that the TMD of the parainfluenza virus 5 (PIV5) fusion protein adopts lipid-dependent conformations and interactions with the membrane and water. In phosphatidylcholine (PC) and phosphatidylglycerol (PG) membranes, the TMD is predominantly α-helical, but in phosphatidylethanolamine (PE) membranes, the TMD changes significantly to the β-strand conformation. Measured order parameters indicate that the strand segments are immobilized and thus oligomerized. (31)P NMR spectra and small-angle X-ray scattering (SAXS) data show that this β-strand-rich conformation converts the PE membrane to a bicontinuous cubic phase, which is rich in negative Gaussian curvature that is characteristic of hemifusion intermediates and fusion pores. (1)H-(31)P 2D correlation spectra and (2)H spectra show that the PE membrane with or without the TMD is much less hydrated than PC and PG membranes, suggesting that the TMD works with the natural dehydration tendency of PE to facilitate membrane merger. These results suggest a new viral-fusion model in which the TMD actively promotes membrane topological changes during fusion using the β-strand as the fusogenic conformation.
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Roche J, Louis JM, Aniana A, Ghirlando R, Bax A. Complete dissociation of the HIV-1 gp41 ectodomain and membrane proximal regions upon phospholipid binding. JOURNAL OF BIOMOLECULAR NMR 2015; 61:235-48. [PMID: 25631354 PMCID: PMC4398632 DOI: 10.1007/s10858-015-9900-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 01/17/2015] [Indexed: 05/22/2023]
Abstract
The envelope glycoprotein gp41 mediates the process of membrane fusion that enables entry of the HIV-1 virus into the host cell. Strong lipid affinity of the ectodomain suggests that its heptad repeat regions play an active role in destabilizing membranes by directly binding to the lipid bilayers and thereby lowering the free-energy barrier for membrane fusion. In such a model, immediately following the shedding of gp120, the N-heptad and C-heptad helices dissociate and melt into the host cell and viral membranes, respectively, pulling the destabilized membranes into juxtaposition, ready for fusion. Post-fusion, reaching the final 6-helix bundle (6 HB) conformation then involves competition between intermolecular interactions needed for formation of the symmetric 6 HB trimer and the membrane affinity of gp41's ectodomain, including its membrane-proximal regions. Our solution NMR study of the structural and dynamic properties of three constructs containing the ectodomain of gp41 with and without its membrane-proximal regions suggests that these segments do not form inter-helical interactions until the very late steps of the fusion process. Interactions between the polar termini of the heptad regions, which are not associating with the lipid surface, therefore may constitute the main driving force initiating formation of the final post-fusion states. The absence of significant intermolecular ectodomain interactions in the presence of dodecyl phosphocholine highlights the importance of trimerization of gp41's transmembrane helix to prevent complete dissociation of the trimer during the course of fusion.
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Affiliation(s)
- Julien Roche
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA
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25
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A cholesterol consensus motif is required for efficient intracellular transport and raft association of a group 2 HA from influenza virus. Biochem J 2015; 465:305-14. [DOI: 10.1042/bj20141114] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The external part of the transmembrane region of HA (haemagglutinin) of influenza virus contains a cholesterol consensus motif originally identified in G-protein-coupled receptors. Various mutations in this motif retard transport of HA through the Golgi and reduce raft association.
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Fu T, Guerette PA, Tan RYT, Zhao H, Schefer L, Mezzenga R, Miserez A. Biomimetic self-assembly of recombinant marine snail egg capsule proteins into structural coiled-coil units. J Mater Chem B 2015; 3:2671-2684. [DOI: 10.1039/c4tb01434k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We report on the biomimetic production of shock-absorbing proteins from marine snail egg capsules and their self-assembly into coiled-coil filaments.
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Affiliation(s)
- Tianpei Fu
- School of Material Science and Engineering
- Nanyang Technological University (NTU)
- Singapore
- Center for Biomimetic Sensor Science
- NTU
| | - Paul A. Guerette
- School of Material Science and Engineering
- Nanyang Technological University (NTU)
- Singapore
- Center for Biomimetic Sensor Science
- NTU
| | - Raymond Y. T. Tan
- School of Material Science and Engineering
- Nanyang Technological University (NTU)
- Singapore
| | - Hua Zhao
- Institute of Chemical and Engineering Sciences (ICES)
- Agency for Science, Technology, and Research (A*Star)
- Singapore
| | - Larissa Schefer
- Department of Health Sciences and Technology
- Swiss Federal Institute of Technology in Zurich (ETHZ)
- 8092 Zürich
- Switzerland
| | - Raffaele Mezzenga
- Department of Health Sciences and Technology
- Swiss Federal Institute of Technology in Zurich (ETHZ)
- 8092 Zürich
- Switzerland
| | - Ali Miserez
- School of Material Science and Engineering
- Nanyang Technological University (NTU)
- Singapore
- Center for Biomimetic Sensor Science
- NTU
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Holtz KM, Robinson PS, Matthews EE, Hashimoto Y, McPherson CE, Khramtsov N, Reifler MJ, Meghrous J, Rhodes DG, Cox MM, Srivastava IK. Modifications of cysteine residues in the transmembrane and cytoplasmic domains of a recombinant hemagglutinin protein prevent cross-linked multimer formation and potency loss. BMC Biotechnol 2014; 14:111. [PMID: 25540031 PMCID: PMC4320835 DOI: 10.1186/s12896-014-0111-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 12/16/2014] [Indexed: 01/19/2023] Open
Abstract
Background Recombinant hemagglutinin (rHA) is the active component in Flublok®; a trivalent influenza vaccine produced using the baculovirus expression vector system (BEVS). HA is a membrane bound homotrimer in the influenza virus envelope, and the purified rHA protein assembles into higher order rosette structures in the final formulation of the vaccine. During purification and storage of the rHA, disulfide mediated cross-linking of the trimers within the rosette occurs and results in reduced potency. Potency is measured by the Single Radial Immuno-diffusion (SRID) assay to determine the amount of HA that has the correct antigenic form. Results The five cysteine residues in the transmembrane (TM) and cytoplasmic (CT) domains of the rHA protein from the H3 A/Perth/16/2009 human influenza strain have been substituted to alanine and/or serine residues to produce three different site directed variants (SDVs). These SDVs have been evaluated to determine the impact of the TM and CT cysteines on potency, cross-linking, and the biochemical and biophysical properties of the rHA. Modification of these cysteine residues prevents disulfide bond cross-linking in the TM and CT, and the resulting rHA maintains potency for at least 12 months at 25°C. The strategy of substituting TM and CT cysteines to prevent potency loss has been successfully applied to another H3 rHA protein (from the A/Texas/50/2012 influenza strain) further demonstrating the utility of the approach. Conclusion rHA potency can be maintained by preventing non-specific disulfide bonding and cross-linked multimer formation. Substitution of carboxy terminal cysteines is an alternative to using reducing agents, and permits room temperature storage of the vaccine.
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Efficient replication of a paramyxovirus independent of full zippering of the fusion protein six-helix bundle domain. Proc Natl Acad Sci U S A 2014; 111:E3795-804. [PMID: 25157143 DOI: 10.1073/pnas.1403609111] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Enveloped viruses such as HIV and members of the paramyxovirus family use metastable, proteinaceous fusion machineries to merge the viral envelope with cellular membranes for infection. A hallmark of the fusogenic glycoproteins of these pathogens is refolding into a thermodynamically highly stable fusion core structure composed of six antiparallel α-helices, and this structure is considered instrumental for pore opening and/or enlargement. Using a paramyxovirus fusion (F) protein, we tested this paradigm by engineering covalently restricted F proteins that are predicted to be unable to close the six-helix bundle core structure fully. Several candidate bonds formed efficiently, resulting in F trimers and higher-order complexes containing covalently linked dimers. The engineered F complexes were incorporated into recombinant virions efficiently and were capable of refolding into a postfusion conformation without temporary or permanent disruption of the disulfide bonds. They efficiently formed fusion pores based on virus replication and quantitative cell-to-cell and virus-to-cell fusion assays. Complementation of these F mutants with a monomeric, fusion-inactive F variant enriched the F oligomers for heterotrimers containing a single disulfide bond, without affecting fusion complementation profiles compared with standard F protein. Our demonstration that complete closure of the fusion core does not drive paramyxovirus entry may aid the design of strategies for inhibiting virus entry.
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Kalani MR, Moradi A, Moradi M, Tajkhorshid E. Characterizing a histidine switch controlling pH-dependent conformational changes of the influenza virus hemagglutinin. Biophys J 2014; 105:993-1003. [PMID: 23972851 DOI: 10.1016/j.bpj.2013.06.047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 06/06/2013] [Accepted: 06/17/2013] [Indexed: 12/11/2022] Open
Abstract
During the fusion of the influenza virus to the host cell, bending of the HA2 chain of hemagglutinin into a hairpin-shaped structure in a pH-dependent manner facilitates the fusion of the viral envelope and the endosomal membrane. To characterize the structural and dynamical responses of the hinge region of HA2 to pH changes and examine the role of a conserved histidine in this region (the hinge histidine), we have performed an extensive set of molecular dynamics (MD) simulations of 26-residue peptides encompassing the hinge regions of several hemagglutinin subtypes under both neutral and low pH conditions, modeled by the change of the protonation state of the hinge histidine. More than 70 sets of MD simulations (collectively amounting to 25.1 μs) were performed in both implicit and explicit solvents to study the effect of histidine protonation on structural dynamics of the hinge region. In both explicit and implicit solvent simulations, hinge bending was consistently observed upon the protonation of the histidine in all the simulations starting with an initial straight helical conformation, whereas the systems with a neutral histidine retained their primarily straight conformation throughout the simulations. Conversely, the MD simulations starting from an initially bent conformation resulted in the formation of a straight helical structure upon the neutralization of the hinge histidine, whereas the bent structure was maintained when the hinge histidine remained protonated. Finally, mutation of the hinge histidine to alanine abolishes the bending response of the peptide altogether. A molecular mechanism based on the interaction of the hinge histidine with neighboring acidic residues is proposed to be responsible for its role in controlling the conformation of the hinge. We propose that this might present a common mechanism for pH-controlled structural changes in helical structures when histidines act as the pH sensor.
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Affiliation(s)
- Mohamad R Kalani
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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30
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Mintaev RR, Alexeevski AV, Kordyukova LV. Co-evolution analysis to predict protein-protein interactions within influenza virus envelope. J Bioinform Comput Biol 2014; 12:1441008. [PMID: 24712535 DOI: 10.1142/s021972001441008x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Interactions between integral membrane proteins hemagglutinin (HA), neuraminidase (NA), M2 and membrane-associated matrix protein M1 of influenza A virus are thought to be crucial for assembly of functionally competent virions. We hypothesized that the amino acid residues located at the interface of two different proteins are under physical constraints and thus probably co-evolve. To predict co-evolving residue pairs, the EvFold ( http://evfold.org ) program searching the (nontransitive) Direct Information scores was applied for large samplings of amino acid sequences from Influenza Research Database ( http://www.fludb.org/ ). Having focused on the HA, NA, and M2 cytoplasmic tails as well as C-terminal domain of M1 (being the less conserved among the protein domains) we captured six pairs of correlated positions. Among them, there were one, two, and three position pairs for HA-M2, HA-M1, and M2-M1 protein pairs, respectively. As expected, no co-varying positions were found for NA-HA, NA-M1, and NA-M2 pairs obviously due to high conservation of the NA cytoplasmic tail. The sum of frequencies calculated for two major amino acid patterns observed in pairs of correlated positions was up to 0.99 meaning their high to extreme evolutionary sustainability. Based on the predictions a hypothetical model of pair-wise protein interactions within the viral envelope was proposed.
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Affiliation(s)
- Ramil R Mintaev
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskie Gory 1-40, Moscow 119991, Russia
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Zhou J, Xu S, Ma J, Lei W, Liu K, Liu Q, Ren Y, Xue C, Cao Y. Recombinant influenza A H3N2 viruses with mutations of HA transmembrane cysteines exhibited altered virological characteristics. Virus Genes 2013; 48:273-82. [PMID: 24272698 DOI: 10.1007/s11262-013-1011-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 11/06/2013] [Indexed: 01/20/2023]
Abstract
Influenza A H3N2 virus as the cause of 1968 pandemic has since been circulating in human and swine. Our earlier study has shown that mutations of one or two cysteines in the transmembrane domain of H3 hemagglutinin (HA) affected the thermal stability and fusion activity of recombinant HA proteins. Here, we report the successful generation of three recombinant H3N2 mutant viruses (C540S, C544L, and 2C/SL) with mutations of one or two transmembrane cysteines of HA in the background of A/swine/Guangdong/01/98 [H3N2] using reverse genetics, indicating that the mutated cysteines were not essential for virus assembly and growth. Further characterization revealed that recombinant H3N2 mutant viruses exhibited larger plaque sizes, increased growth rate in cells, enhanced fusion activity, reduced thermal and acidic resistances, and increased virulence in embryonated eggs. These results demonstrated that the transmembrane cysteines (C540 and C544) in H3 HA have profound effects on the virological features of H3N2 viruses.
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Affiliation(s)
- Jianqiang Zhou
- State Key Laboratory of Biocontrol, Life Sciences School, Guangzhou Higher Education Mega Center, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China
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Smith EC, Smith SE, Carter JR, Webb SR, Gibson KM, Hellman LM, Fried MG, Dutch RE. Trimeric transmembrane domain interactions in paramyxovirus fusion proteins: roles in protein folding, stability, and function. J Biol Chem 2013; 288:35726-35. [PMID: 24178297 DOI: 10.1074/jbc.m113.514554] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Paramyxovirus fusion (F) proteins promote membrane fusion between the viral envelope and host cell membranes, a critical early step in viral infection. Although mutational analyses have indicated that transmembrane (TM) domain residues can affect folding or function of viral fusion proteins, direct analysis of TM-TM interactions has proved challenging. To directly assess TM interactions, the oligomeric state of purified chimeric proteins containing the Staphylococcal nuclease (SN) protein linked to the TM segments from three paramyxovirus F proteins was analyzed by sedimentation equilibrium analysis in detergent and buffer conditions that allowed density matching. A monomer-trimer equilibrium best fit was found for all three SN-TM constructs tested, and similar fits were obtained with peptides corresponding to just the TM region of two different paramyxovirus F proteins. These findings demonstrate for the first time that class I viral fusion protein TM domains can self-associate as trimeric complexes in the absence of the rest of the protein. Glycine residues have been implicated in TM helix interactions, so the effect of mutations at Hendra F Gly-508 was assessed in the context of the whole F protein. Mutations G508I or G508L resulted in decreased cell surface expression of the fusogenic form, consistent with decreased stability of the prefusion form of the protein. Sedimentation equilibrium analysis of TM domains containing these mutations gave higher relative association constants, suggesting altered TM-TM interactions. Overall, these results suggest that trimeric TM interactions are important driving forces for protein folding, stability and membrane fusion promotion.
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Affiliation(s)
- Everett Clinton Smith
- From the Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536
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Mineev KS, Lyukmanova EN, Krabben L, Serebryakova MV, Shulepko MA, Arseniev AS, Kordyukova LV, Veit M. Structural investigation of influenza virus hemagglutinin membrane-anchoring peptide. Protein Eng Des Sel 2013; 26:547-52. [PMID: 23873663 DOI: 10.1093/protein/gzt034] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hemagglutinin (HA), the trimeric spike of influenza virus, catalyzes fusion of viral and cellular membranes. We have synthesized the anchoring peptide including the linker, transmembrane region and cytoplasmic tail (HA-TMR-CT) in a cell-free system. Furthermore, to mimic the palmitoylation of three conserved cysteines within the CT, we chemically alkylated HA-TMR-CT using hexadecyl-methanethiosulfonate. While the nuclear magnetic resonance spectroscopy showed pure and refolded peptides, the formation of multiple oligomers of higher order impeded further structural analysis. Circular dichroism spectroscopy of both alkylated and non-alkylated HA-TMR-CT revealed an α-helical secondary structure. No major impact of the fatty acids on the secondary structure was detected.
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Affiliation(s)
- Konstantin S Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, 117997 Moscow, Russia
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Tatulian SA. Structural characterization of membrane proteins and peptides by FTIR and ATR-FTIR spectroscopy. Methods Mol Biol 2013; 974:177-218. [PMID: 23404277 DOI: 10.1007/978-1-62703-275-9_9] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Fourier transform infrared (FTIR) spectroscopy is widely used in structural characterization of proteins or peptides. While the method does not have the capability of providing the precise, atomic-resolution molecular structure, it is exquisitely sensitive to conformational changes occurring in proteins upon functional transitions or upon intermolecular interactions. Sensitivity of vibrational frequencies to atomic masses has led to development of "isotope-edited" FTIR spectroscopy, where structural effects in two proteins, one unlabeled and the other labeled with a heavier stable isotope, such as (13)C, are resolved simultaneously based on spectral downshift (separation) of the amide I band of the labeled protein. The same isotope effect is used to identify site-specific conformational changes in proteins by site-directed or segmental isotope labeling. Negligible light scattering in the infrared region provides an opportunity to study intermolecular interactions between large protein complexes, interactions of proteins and peptides with lipid vesicles, or protein-nucleic acid interactions without light scattering problems often encountered in ultraviolet spectroscopy. Attenuated total reflection FTIR (ATR-FTIR) is a surface-sensitive version of infrared spectroscopy that has proved useful in studying membrane proteins and lipids, protein-membrane interactions, mechanisms of interfacial enzymes, and molecular architecture of membrane pore or channel forming proteins and peptides. The purpose of this article was to provide a practical guide to analyze protein structure and protein-membrane interactions by FTIR and ATR-FTIR techniques, including procedures of sample preparation, measurements, and data analysis. Basic background information on FTIR spectroscopy, as well as some relatively new developments in structural and functional characterization of proteins and peptides in lipid membranes, are also presented.
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Affiliation(s)
- Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, FL, USA.
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35
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Victor BL, Baptista AM, Soares CM. Structural determinants for the membrane insertion of the transmembrane peptide of hemagglutinin from influenza virus. J Chem Inf Model 2012; 52:3001-12. [PMID: 23101989 DOI: 10.1021/ci3003396] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Membrane fusion is a process involved in a high range of biological functions, going from viral infections to neurotransmitter release. Fusogenic proteins increase the slow rate of fusion by coupling energetically downhill conformational changes of the protein to the kinetically unfavorable fusion of the membrane lipid bilayers. Hemagglutinin is an example of a fusogenic protein, which promotes the fusion of the membrane of the influenza virus with the membrane of the target cell. The N-terminus of the HA2 subunit of this protein contains a fusion domain described to act as a destabilizer of the target membrane bilayers, leading eventually to a full fusion of the two membranes. On the other hand, the C-terminus of the same subunit contains a helical transmembrane domain which was initially described to act as the anchor of the protein to the membrane of the virus. However, in recent years the study of this peptide segment has been gaining more attention since it has also been described to be involved in the membrane fusion process. Yet, the structural characterization of the interaction of such a protein domain with membrane lipids is still very limited. Therefore, in this work, we present a study of this transmembrane peptide domain in the presence of DMPC membrane bilayers, and we evaluate the effect of several mutations, and the effect of peptide oligomerization in this interaction process. Our results allowed us to identify and confirm amino acid residue motifs that seem to regulate the interaction between the segment peptide and membrane bilayers. Besides these sequence requirements, we have also identified length and tilt requirements that ultimately contribute to the hydrophobic matching between the peptide and the membrane. Additionally, we looked at the association of several transmembrane peptide segments and evaluated their direct interaction and stability inside a membrane bilayer. From our results we could conclude that three independent TM peptide segments arrange themselves in a parallel arrangement, very similarly to what is observed for the C-terminal regions of the hemagglutinin crystallographic structure of the protein, to where the segments are attached.
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Affiliation(s)
- Bruno L Victor
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa Avenida da República, EAN Apartado 127, 2781-901 Oeiras, Portugal.
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Reuven EM, Dadon Y, Viard M, Manukovsky N, Blumenthal R, Shai Y. HIV-1 gp41 transmembrane domain interacts with the fusion peptide: implication in lipid mixing and inhibition of virus-cell fusion. Biochemistry 2012; 51:2867-78. [PMID: 22413880 PMCID: PMC3335273 DOI: 10.1021/bi201721r] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fusion of the human immunodeficiency virus (HIV) with target cells is mediated by the gp41 subunit of the envelope protein. Mutation and deletion studies within the transmembrane domain (TMD) of intact gp41 influenced its fusion activity. In addition, current models suggest that the TMD is in proximity with the fusion peptide (FP) at the late fusion stages, but there are no direct experimental data to support this hypothesis. Here, we investigated the TMD focusing on two regions: the N-terminal containing the GxxxG motif and the C-terminal containing the GLRI motif, which is conserved among the TMDs of HIV and the T-cell receptor. Studies utilizing the ToxR expression system combined with synthetic peptides and their fluorescent analogues derived from TMD revealed that the GxxxG motif is important for TMD self-association, whereas the C-terminal region is for its heteroassociation with FP. Functionally, all three TMD peptides induced lipid mixing that was enhanced significantly upon mixing with FP. Furthermore, the TMD peptides inhibited virus-cell fusion apparently through their interaction with their endogenous counterparts. Notably, the R2E mutant (in the GLRI) was significantly less potent than the two others. Overall, our findings provide experimental evidence that HIV-1 TMD contributes to membrane assembly and function of the HIV-1 envelope. Owing to similarities between functional domains within viruses, these findings suggest that the TMDs and FPs may contribute similarly in other viruses as well.
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Affiliation(s)
- Eliran Moshe Reuven
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, 76100 Israel
| | - Yakir Dadon
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, 76100 Israel
| | - Mathias Viard
- Basic Research Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702
- Nanobiology Program, Center of Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Nurit Manukovsky
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, 76100 Israel
| | - Robert Blumenthal
- Basic Research Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702
| | - Yechiel Shai
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, 76100 Israel
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Collins R, Holz R, Zimmerberg J. 5.14 The Biophysics of Membrane Fusion. COMPREHENSIVE BIOPHYSICS 2012. [PMCID: PMC7151979 DOI: 10.1016/b978-0-12-374920-8.00523-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A crucial interplay between protein conformations and lipid membrane energetics emerges as the guiding principle for the regulation and mechanism of membrane fusion in biological systems. As some of the basics of fusion become clear, a myriad of compelling questions come to the fore. Is the interior of the fusion pore protein or lipid? Why is synaptic release so fast? Why is PIP2 needed for exocytosis? How does fusion peptide insertion lead to fusion of viruses to cell membranes? What role does the TMD play? How can studies on membrane fission contribute to our understanding of membrane fusion? What exactly are SNARE proteins doing?
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38
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Keller RCA. New user-friendly approach to obtain an Eisenberg plot and its use as a practical tool in protein sequence analysis. Int J Mol Sci 2011; 12:5577-91. [PMID: 22016610 PMCID: PMC3189734 DOI: 10.3390/ijms12095577] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 08/22/2011] [Accepted: 08/22/2011] [Indexed: 12/26/2022] Open
Abstract
The Eisenberg plot or hydrophobic moment plot methodology is one of the most frequently used methods of bioinformatics. Bioinformatics is more and more recognized as a helpful tool in Life Sciences in general, and recent developments in approaches recognizing lipid binding regions in proteins are promising in this respect. In this study a bioinformatics approach specialized in identifying lipid binding helical regions in proteins was used to obtain an Eisenberg plot. The validity of the Heliquest generated hydrophobic moment plot was checked and exemplified. This study indicates that the Eisenberg plot methodology can be transferred to another hydrophobicity scale and renders a user-friendly approach which can be utilized in routine checks in protein–lipid interaction and in protein and peptide lipid binding characterization studies. A combined approach seems to be advantageous and results in a powerful tool in the search of helical lipid-binding regions in proteins and peptides. The strength and limitations of the Eisenberg plot approach itself are discussed as well. The presented approach not only leads to a better understanding of the nature of the protein–lipid interactions but also provides a user-friendly tool for the search of lipid-binding regions in proteins and peptides.
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Affiliation(s)
- Rob C A Keller
- Section Chemistry, Charlemagne College, Wilhelminastraat 13-15, 6524 AJ Nijmegen, The Netherlands; E-Mail: ; Tel.: +0031-243820460
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Abstract
As all the enveloped viruses, the entry of influenza viruses includes a number of steps in host cell infection. This chapter summarizes the current knowledge of the entry pathway and the role of the fusion protein of influenza virus, hemagglutinin, in this process. Hemagglutinin (HA) is a trimeric glycoprotein that is present in multiple copies in the membrane envelope of influenza virus. HA contains a fusion peptide, a receptor binding site, a metastable structural motif, and the transmembrane domain. The first step of influenza virus entry is the recognition of the host cell receptor molecule, terminal α-sialic acid, by HA. This multivalent attachment by multiple copies of trimetric HA triggers endocytosis of influenza virus that is contained in the endosome. The endosome-trapped virus traffics via a unidirectional pathway to near the nucleus. At this location, the interior pH of the endosome becomes acidic that induces a dramatic conformational change in HA to insert the fusion peptide into the host membrane, induce juxtaposition of the two membranes, and form a fusion pore that allows the release of the genome segments of influenza virus. HA plays a key role in the entire entry pathway. Inhibitors of virus entry are potentially effective antiviral drugs of influenza viruses.
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Affiliation(s)
- Michael G. Rossmann
- grid.169077.e0000000419372197Dept. Biological Sciences, Purdue University, W. State St. 915, West Lafayette, 47907-2054 Indiana USA
| | - Venigalla B. Rao
- grid.39936.360000000121746686Dept. Biology, Catholic University of America, Washington, 20064 District of Columbia USA
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Neumann S, Langosch D. Conserved conformational dynamics of membrane fusion protein transmembrane domains and flanking regions indicated by sequence statistics. Proteins 2011; 79:2418-27. [DOI: 10.1002/prot.23063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Revised: 03/26/2011] [Accepted: 04/19/2011] [Indexed: 11/07/2022]
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Ge M, Freed JH. Two conserved residues are important for inducing highly ordered membrane domains by the transmembrane domain of influenza hemagglutinin. Biophys J 2011; 100:90-7. [PMID: 21190660 PMCID: PMC3010018 DOI: 10.1016/j.bpj.2010.11.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/25/2010] [Accepted: 11/08/2010] [Indexed: 11/25/2022] Open
Abstract
The interaction with lipids of a synthetic peptide corresponding to the transmembrane domain of influenza hemagglutinin was investigated by means of electron spin resonance. A detailed analysis of the electron spin resonance spectra from spin-labeled phospholipids revealed that the major effect of the peptide on the dynamic membrane structure is to induce highly ordered membrane domains that are associated with electrostatic interactions between the peptide and negatively charged lipids. Two highly conserved residues in the peptide were identified as being important for the membrane ordering effect. Aggregation of large unilamellar vesicles induced by the peptide was also found to be correlated with the membrane ordering effect of the peptide, indicating that an increase in membrane ordering, i.e., membrane dehydration, is important for vesicle aggregation. The possibility that hydrophobic interaction between the highly ordered membrane domains plays a role in vesicle aggregation and viral fusion is discussed.
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42
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Kordyukova LV, Serebryakova MV, Polyansky AA, Kropotkina EA, Alexeevski AV, Veit M, Efremov RG, Filippova IY, Baratova LA. Linker and/or transmembrane regions of influenza A/Group-1, A/Group-2, and type B virus hemagglutinins are packed differently within trimers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1843-54. [PMID: 21420932 DOI: 10.1016/j.bbamem.2011.03.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2010] [Revised: 03/11/2011] [Accepted: 03/15/2011] [Indexed: 11/19/2022]
Abstract
Influenza virus hemagglutinin is a homotrimeric spike glycoprotein crucial for virions' attachment, membrane fusion, and assembly reactions. X-ray crystallography data are available for hemagglutinin ectodomains of various types/subtypes but not for anchoring segments. To get structural information for the linker and transmembrane regions of hemagglutinin, influenza A (H1-H16 subtypes except H8 and H15) and B viruses were digested with bromelain or subtilisin Carlsberg, either within virions or in non-ionic detergent micelles. Proteolytical fragments were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Within virions, hemagglutinins of most influenza A/Group-1 and type B virus strains were more susceptible to digestion with bromelain and/or subtilisin compared to A/Group-2 hemagglutinins. The cleavage sites were always located in the hemagglutinin linker sequence. In detergent, 1) bromelain cleaved hemagglutinin of every influenza A subtype in the linker region; 2) subtilisin cleaved Group-2 hemagglutinins in the linker region; 3) subtilisin cleaved Group-1 hemagglutinins in the transmembrane region; 4) both enzymes cleaved influenza B virus hemagglutinin in the transmembrane region. We propose that the A/Group-2 hemagglutinin linker and/or transmembrane regions are more tightly associated within trimers than type A/Group-1 and particularly type B ones. This hypothesis is underpinned by spatial trimeric structure modeling performed for transmembrane regions of both Group-1 and Group-2 hemagglutinin representatives. Differential S-acylation of the hemagglutinin C-terminal anchoring segment with palmitate/stearate residues possibly contributes to fine tuning of transmembrane trimer packing and stabilization since decreased stearate amount correlated with deeper digestion of influenza B and some A/Group-1 hemagglutinins.
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Affiliation(s)
- Larisa V Kordyukova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
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43
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Helix-destabilizing, beta-branched, and polar residues in the baboon reovirus p15 transmembrane domain influence the modularity of FAST proteins. J Virol 2011; 85:4707-19. [PMID: 21367887 DOI: 10.1128/jvi.02223-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The fusogenic reoviruses induce syncytium formation using the fusion-associated small transmembrane (FAST) proteins. A recent study indicated the p14 FAST protein transmembrane domain (TMD) can be functionally replaced by the TMDs of the other FAST proteins but not by heterologous TMDs, suggesting that the FAST protein TMDs are modular fusion units. We now show that the p15 FAST protein is also a modular fusogen, as indicated by the functional replacement of the p15 ectodomain with the corresponding domain from the p14 FAST protein. Paradoxically, the p15 TMD is not interchangeable with the TMDs of the other FAST proteins, implying that unique attributes of the p15 TMD are required when this fusion module is functioning in the context of the p15 ecto- and/or endodomain. A series of point substitutions, truncations, and reextensions were created in the p15 TMD to define features that are specific to the functioning of the p15 TMD. Removal of only one or two residues from the N terminus or four residues from the C terminus of the p15 TMD eliminated membrane fusion activity, and there was a direct correlation between the fusion-promoting function of the p15 TMD and the presence of N-terminal, hydrophobic β-branched residues. Substitution of the glycine residues and triserine motif present in the p15 TMD also impaired or eliminated the fusion-promoting activity of the p15 TMD. The ability of the p15 TMD to function in an ecto- and endodomain-specific context is therefore influenced by stringent sequence requirements that reflect the importance of TMD polar residues and helix-destabilizing residues.
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Nikolaus J, Warner JM, O'Shaughnessy B, Herrmann A. The pathway to membrane fusion through hemifusion. CURRENT TOPICS IN MEMBRANES 2011; 68:1-32. [PMID: 21771493 DOI: 10.1016/b978-0-12-385891-7.00001-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Jörg Nikolaus
- Department of Biology, Faculty of Mathematics and Natural Sciences I, Humboldt-University Berlin, Berlin, Germany
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45
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Nikolaus J, Scolari S, Bayraktarov E, Jungnick N, Engel S, Pia Plazzo A, Stöckl M, Volkmer R, Veit M, Herrmann A. Hemagglutinin of influenza virus partitions into the nonraft domain of model membranes. Biophys J 2010; 99:489-98. [PMID: 20643067 DOI: 10.1016/j.bpj.2010.04.027] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 04/07/2010] [Accepted: 04/12/2010] [Indexed: 11/16/2022] Open
Abstract
The HA of influenza virus is a paradigm for a transmembrane protein thought to be associated with membrane-rafts, liquid-ordered like nanodomains of the plasma membrane enriched in cholesterol, glycosphingolipids, and saturated phospholipids. Due to their submicron size in cells, rafts can not be visualized directly and raft-association of HA was hitherto analyzed by indirect methods. In this study, we have used GUVs and GPMVs, showing liquid disordered and liquid ordered domains, to directly visualize partition of HA by fluorescence microscopy. We show that HA is exclusively (GUVs) or predominantly (GPMVs) present in the liquid disordered domain, regardless of whether authentic HA or domains containing its raft targeting signals were reconstituted into model membranes. The preferential partition of HA into ld domains and the difference between lo partition in GUV and GPMV are discussed with respect to differences in packaging of lipids in membranes of model systems and living cells suggesting that physical properties of lipid domains in biological membranes are tightly regulated by protein-lipid interactions.
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Affiliation(s)
- Jörg Nikolaus
- Department of Biology, Molecular Biophysics, Humboldt University Berlin, Berlin, Germany
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46
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Chan RB, Tanner L, Wenk MR. Implications for lipids during replication of enveloped viruses. Chem Phys Lipids 2010; 163:449-59. [PMID: 20230810 PMCID: PMC7124286 DOI: 10.1016/j.chemphyslip.2010.03.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 03/08/2010] [Indexed: 01/27/2023]
Abstract
Enveloped viruses, which include many medically important viruses such as human immunodeficiency virus, influenza virus and hepatitis C virus, are intracellular parasites that acquire lipid envelopes from their host cells. Success of replication is intimately linked to their ability to hijack host cell mechanisms, particularly those related to membrane dynamics and lipid metabolism. Despite recent progress, our knowledge of lipid mediated virus-host interactions remains highly incomplete. In addition, diverse experimental systems are used to study different stages of virus replication thus complicating comparisons. This review aims to present a unifying view of the widely diverse strategies used by enveloped viruses at distinct stages of their replication cycles.
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Affiliation(s)
- Robin B Chan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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47
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Abstract
Membrane-active peptides or protein segments play an important role in many biological processes at the cellular interface to the environment. They are involved, e.g., in cellular fusion or host defense, where they can cause not only merging but also the destabilization of cell membranes. Many factors determine how these typically amphipathic peptides interact with the lipid bilayer. For example, the peptide orientation in the membrane determines which parts of the peptide are exposed to the hydrophobic bilayer interior or to the polar lipid/water interface. As another example, oligomerization is required for many activities such as pore formation. Peptides have been often classified according to a single characteristic mode of interaction with the bilayer, but over the years a more versatile picture has emerged. It appears that any single peptide can adopt several different alignments and/or oligomeric states in response to changes in the environment. For instance, many antimicrobial peptides adopt a surface-parallel alignment at low concentration, but they tilt obliquely into or even fully insert transmembrane into the bilayer above a critical peptide-to-lipid ratio, often in the form of oligomeric pores. Similar changes in peptide orientation or oligomeric state have been observed as a function of, e.g., temperature, lipid composition, pH, or induced by a synergistic partner peptide. Such transitions between peptide states can be regarded as the result of a re-adjustment in the balance between peptide-peptide and peptide-lipid interactions, as the environment conditions are changed. Though often studied in model membrane systems, such rich variety of peptide states is even more likely to occur in native biomembranes with their diverse compositions and physicochemical properties. The ability to undergo transitions between different states thus plays a fundamental role for the biological activities of membrane-active peptides.
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Affiliation(s)
- Stephan L Grage
- Karlsruhe Institute of Technology, Institute for Biological Interfaces (IBG-2), Institute of Organic Chemistry, Karlsruhe, Germany
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48
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Liu J, Strzalka J, Tronin A, Johansson JS, Blasie JK. Mechanism of interaction between the general anesthetic halothane and a model ion channel protein, II: Fluorescence and vibrational spectroscopy using a cyanophenylalanine probe. Biophys J 2009; 96:4176-87. [PMID: 19450488 DOI: 10.1016/j.bpj.2009.01.055] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Revised: 12/02/2008] [Accepted: 01/07/2009] [Indexed: 11/15/2022] Open
Abstract
We demonstrate that cyano-phenylalanine (Phe(CN)) can be utilized to probe the binding of the inhalational anesthetic halothane to an anesthetic-binding, model ion channel protein hbAP-Phe(CN). The Trp to Phe(CN) mutation alters neither the alpha-helical conformation nor the 4-helix bundle structure. The halothane binding properties of this Phe(CN) mutant hbAP-Phe(CN), based on fluorescence quenching, are consistent with those of the prototype, hbAP1. The dependence of fluorescence lifetime as a function of halothane concentration implies that the diffusion of halothane in the nonpolar core of the protein bundle is one-dimensional. As a consequence, at low halothane concentrations, the quenching of the fluorescence is dynamic, whereas at high concentrations the quenching becomes static. The 4-helix bundle structure present in aqueous detergent solution and at the air-water interface, is preserved in multilayer films of hbAP-Phe(CN), enabling vibrational spectroscopy of both the protein and its nitrile label (-CN). The nitrile groups' stretching vibration band shifts to higher frequency in the presence of halothane, and this blue-shift is largely reversible. Due to the complexity of this amphiphilic 4-helix bundle model membrane protein, where four Phe(CN) probes are present adjacent to the designed cavity forming the binding site within each bundle, all contributing to the infrared absorption, molecular dynamics (MD) simulation is required to interpret the infrared results. The MD simulations indicate that the blue-shift of -CN stretching vibration induced by halothane arises from an indirect effect, namely an induced change in the electrostatic protein environment averaged over the four probe oscillators, rather than a direct interaction with the oscillators. hbAP-Phe(CN) therefore provides a successful template for extending these investigations of the interactions of halothane with the model membrane protein via vibrational spectroscopy, using cyano-alanine residues to form the anesthetic binding cavity.
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Affiliation(s)
- Jing Liu
- Departments of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Schibli DJ, Weissenhorn W. Class I and class II viral fusion protein structures reveal similar principles in membrane fusion (Review). Mol Membr Biol 2009; 21:361-71. [PMID: 15764366 DOI: 10.1080/09687860400017784] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Recent crystal structures of Flavivirus and Alphavirus fusion proteins (class II) confirm two major principles of protein machineries that mediate the merger of two opposing lipid bilayers. First, the fusion protein can bridge both membranes tethered by two membrane anchors. Second, refolding or domain rearrangement steps lead to the positioning of both anchors into close proximity at the same end of an elongated structure. Although these two steps are in principle sufficient to pull two opposing membranes together and initiate membrane fusion, accumulating evidence suggests that the process requires the concerted action of a number of fusion proteins at and outside the contact sites. This review will focus on the structures of viral class I and class II fusion proteins and their similarities in facilitating membrane fusion.
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50
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Langosch D, Arkin IT. Interaction and conformational dynamics of membrane-spanning protein helices. Protein Sci 2009; 18:1343-58. [PMID: 19530249 PMCID: PMC2775205 DOI: 10.1002/pro.154] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 04/19/2009] [Accepted: 04/20/2009] [Indexed: 12/23/2022]
Abstract
Within 1 or 2 decades, the reputation of membrane-spanning alpha-helices has changed dramatically. Once mostly regarded as dull membrane anchors, transmembrane domains are now recognized as major instigators of protein-protein interaction. These interactions may be of exquisite specificity in mediating assembly of stable membrane protein complexes from cognate subunits. Further, they can be reversible and regulatable by external factors to allow for dynamic changes of protein conformation in biological function. Finally, these helices are increasingly regarded as dynamic domains. These domains can move relative to each other in different functional protein conformations. In addition, small-scale backbone fluctuations may affect their function and their impact on surrounding lipid shells. Elucidating the ways by which these intricate structural features are encoded by the amino acid sequences will be a fascinating subject of research for years to come.
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Affiliation(s)
- Dieter Langosch
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany.
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