scholarly journals Palmitoylation Contributes to Membrane Curvature in Influenza A Virus Assembly and Hemagglutinin-Mediated Membrane Fusion

2017 ◽  
Vol 91 (21) ◽  
Author(s):  
Petr Chlanda ◽  
Elena Mekhedov ◽  
Hang Waters ◽  
Alexander Sodt ◽  
Cindi Schwartz ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Influenza A Virus ◽  
Influenza A ◽  
Electron Tomography ◽  
Virus Assembly ◽  
Membrane Curvature ◽  
Fusion Pore ◽  
M1 Protein ◽  
Cryo Electron Tomography ◽  
Pore Expansion

ABSTRACT The highly conserved cytoplasmic tail of influenza virus glycoprotein hemagglutinin (HA) contains three cysteines, posttranslationally modified by covalently bound fatty acids. While viral HA acylation is crucial in virus replication, its physico-chemical role is unknown. We used virus-like particles (VLP) to study the effect of acylation on morphology, protein incorporation, lipid composition, and membrane fusion. Deacylation interrupted HA-M1 interactions since deacylated mutant HA failed to incorporate an M1 layer within spheroidal VLP, and filamentous particles incorporated increased numbers of neuraminidase (NA). While HA acylation did not influence VLP shape, lipid composition, or HA lateral spacing, acylation significantly affected envelope curvature. Compared to wild-type HA, deacylated HA is correlated with released particles with flat envelope curvature in the absence of the matrix (M1) protein layer. The spontaneous curvature of palmitate was calculated by molecular dynamic simulations and was found to be comparable to the curvature values derived from VLP size distributions. Cell-cell fusion assays show a strain-independent failure of fusion pore enlargement among H2 (A/Japan/305/57), H3 (A/Aichi/2/68), and H3 (A/Udorn/72) viruses. In contradistinction, acylation made no difference in the low-pH-dependent fusion of isolated VLPs to liposomes: fusion pores formed and expanded, as demonstrated by the presence of complete fusion products observed using cryo-electron tomography (cryo-ET). We propose that the primary mechanism of action of acylation is to control membrane curvature and to modify HA's interaction with M1 protein, while the stunting of fusion by deacylated HA acting in isolation may be balanced by other viral proteins which help lower the energetic barrier to pore expansion. IMPORTANCE Influenza A virus is an airborne pathogen causing seasonal epidemics and occasional pandemics. Hemagglutinin (HA), a glycoprotein abundant on the virion surface, is important in both influenza A virus assembly and entry. HA is modified by acylation whose removal abrogates viral replication. Here, we used cryo-electron tomography to obtain three-dimensional images to elucidate a role for HA acylation in VLP assembly. Our data indicate that HA acylation contributes to the capability of HA to bend membranes and to HA's interaction with the M1 scaffold protein during virus assembly. Furthermore, our data on VLP and, by hypothesis, virus suggests that HA acylation, while not critical to fusion pore formation, contributes to pore expansion in a target-dependent fashion.

scholarly journals Hemagglutinin Palmitoylation Contributes to Membrane Curvature in Influenza a Virus Assembly and Membrane Fusion

2017 ◽  
Vol 112 (3) ◽  
pp. 80a
Author(s):  
Petr Chlanda ◽  
Elena Mekhedov ◽  
Hang Waters ◽  
Alexander Sodt ◽  
Paul S. Blank ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Influenza A Virus ◽  
Influenza A ◽  
Virus Assembly ◽  
Membrane Curvature

scholarly journals Distinct Domains of the Influenza A Virus M2 Protein Cytoplasmic Tail Mediate Binding to the M1 Protein and Facilitate Infectious Virus Production

2006 ◽  
Vol 80 (16) ◽  
pp. 8178-8189 ◽  
Author(s):  
Matthew F. McCown ◽  
Andrew Pekosz
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Reverse Genetics ◽  
Infectious Virus ◽  
Virus Assembly ◽  
Virus Production ◽  
Cytoplasmic Tail ◽  
M2 Protein ◽  
Virus Particles ◽  
M1 Protein

ABSTRACT The cytoplasmic tail of the influenza A virus M2 protein is highly conserved among influenza A virus isolates. The cytoplasmic tail appears to be dispensable with respect to the ion channel activity associated with the protein but important for virus morphology and the production of infectious virus particles. Using reverse genetics and transcomplementation assays, we demonstrate that the M2 protein cytoplasmic tail is a crucial mediator of infectious virus production. Truncations of the M2 cytoplasmic tail result in a drastic decrease in infectious virus titers, a reduction in the amount of packaged viral RNA, a decrease in budding events, and a reduction in budding efficiency. The M1 protein binds to the M2 cytoplasmic tail, but the M1 binding site is distinct from the sequences that affect infectious virus particle formation. Influenza A virus strains A/Udorn/72 and A/WSN/33 differ in their requirements for M2 cytoplasmic tail sequences, and this requirement maps to the M1 protein. We conclude that the M2 protein is required for the formation of infectious virus particles, implicating the protein as important for influenza A virus assembly in addition to its well-documented role during virus entry and uncoating.

scholarly journals Structural Analysis of the Roles of Influenza A Virus Membrane-Associated Proteins in Assembly and Morphology

2015 ◽  
Vol 89 (17) ◽  
pp. 8957-8966 ◽  
Author(s):  
Petr Chlanda ◽  
Oliver Schraidt ◽  
Susann Kummer ◽  
James Riches ◽  
Heike Oberwinkler ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Electron Tomography ◽  
Virus Assembly ◽  
Viral Proteins ◽  
Particle Release ◽  
Virus Like Particles ◽  
Virus Particles ◽  
M Proteins ◽  
Associated Proteins

ABSTRACTThe assembly of influenza A virus at the plasma membrane of infected cells leads to release of enveloped virions that are typically round in tissue culture-adapted strains but filamentous in strains isolated from patients. The viral proteins hemagglutinin (HA), neuraminidase (NA), matrix protein 1 (M1), and M2 ion channel all contribute to virus assembly. When expressed individually or in combination in cells, they can all, under certain conditions, mediate release of membrane-enveloped particles, but their relative roles in virus assembly, release, and morphology remain unclear. To investigate these roles, we produced membrane-enveloped particles by plasmid-derived expression of combinations of HA, NA, and M proteins (M1 and M2) or by infection with influenza A virus. We monitored particle release, particle morphology, and plasma membrane morphology by using biochemical methods, electron microscopy, electron tomography, and cryo-electron tomography. Our data suggest that HA, NA, or HANA (HA plus NA) expression leads to particle release through nonspecific induction of membrane curvature. In contrast, coexpression with the M proteins clusters the glycoproteins into filamentous membrane protrusions, which can be released as particles by formation of a constricted neck at the base. HA and NA are preferentially distributed to differently curved membranes within these particles. Both the budding intermediates and the released particles are morphologically similar to those produced during infection with influenza A virus. Together, our data provide new insights into influenza virus assembly and show that the M segment together with either of the glycoproteins is the minimal requirement to assemble and release membrane-enveloped particles that are truly virus-like.IMPORTANCEInfluenza A virus is a major respiratory pathogen. It assembles membrane-enveloped virus particles whose shapes vary from spherical to filamentous. Here we examine the roles of individual viral proteins in mediating virus assembly and determining virus shape. To do this, we used a range of electron microscopy techniques to obtain and compare two- and three-dimensional images of virus particles and virus-like particles during and after assembly. The virus-like particles were produced using different combinations of viral proteins. Among our results, we found that coexpression of one or both of the viral surface proteins (hemagglutinin and neuraminidase) with the viral membrane-associated proteins encoded by the M segment results in assembly and release of filamentous virus-like particles in a manner very similar to that of the budding and release of influenza virions. These data provide novel insights into the roles played by individual viral proteins in influenza A virus assembly.

scholarly journals Cyclophilin A interacts with influenza A virus M1 protein and impairs the early stage of the viral replication

2009 ◽  
Vol 11 (5) ◽  
pp. 730-741 ◽  
Author(s):  
Xiaoling Liu ◽  
Lei Sun ◽  
Maorong Yu ◽  
Zengfu Wang ◽  
Chongfeng Xu ◽  
...  
Keyword(s):  
Viral Replication ◽  
Influenza A Virus ◽  
Influenza A ◽  
Early Stage ◽  
Cyclophilin A ◽  
M1 Protein

Chemoreactive-Inspired Discovery of Influenza A Virus Dual Inhibitor to Block Hemagglutinin-Mediated Adsorption and Membrane Fusion

2020 ◽  
Vol 63 (13) ◽  
pp. 6924-6940
Author(s):  
Guangwei Wu ◽  
Guihong Yu ◽  
Yunjia Yu ◽  
Shuang Yang ◽  
Zhongwei Duan ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Influenza A Virus ◽  
Influenza A ◽  
Dual Inhibitor

Matrix proteins of enveloped viruses: a case study of Influenza A virus M1 protein

2018 ◽  
Vol 37 (3) ◽  
pp. 671-690 ◽  
Author(s):  
Larisa V. Kordyukova ◽  
Eleonora V. Shtykova ◽  
Lyudmila A. Baratova ◽  
Dmitri I. Svergun ◽  
Oleg V. Batishchev
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Matrix Proteins ◽  
Enveloped Viruses ◽  
M1 Protein

scholarly journals Influenza Virus Matrix Protein Is the Major Driving Force in Virus Budding

2000 ◽  
Vol 74 (24) ◽  
pp. 11538-11547 ◽  
Author(s):  
Paulino Gómez-Puertas ◽  
Carmen Albo ◽  
Esperanza Pérez-Pastrana ◽  
Amparo Vivo ◽  
Agustı́n Portela
Keyword(s):  
Virus Particle ◽  
Influenza A ◽  
Matrix Protein ◽  
Virus Assembly ◽  
Microscopic Analysis ◽  
Tubular Structures ◽  
Electron Microscopic ◽  
Particle Assembly ◽  
M1 Protein ◽  
The Matrix

ABSTRACT To get insights into the role played by each of the influenza A virus polypeptides in morphogenesis and virus particle assembly, the generation of virus-like particles (VLPs) has been examined in COS-1 cell cultures expressing, from recombinant plasmids, different combinations of the viral structural proteins. The presence of VLPs was examined biochemically, following centrifugation of the supernatants collected from transfected cells through sucrose cushions and immunoblotting, and by electron-microscopic analysis. It is demonstrated that the matrix (M1) protein is the only viral component which is essential for VLP formation and that the viral ribonucleoproteins are not required for virus particle formation. It is also shown that the M1 protein, when expressed alone, assembles into virus-like budding particles, which are released in the culture medium, and that the recombinant M1 protein accumulates intracellularly, forming tubular structures. All these results are discussed with regard to the roles played by the virus polypeptides during virus assembly.

Sign in / Sign up

Export Citation Format

Share Document