title: Phosphatidylserine Lateral Organization Influences the Interaction of Influenza Virus Matrix Protein 1 with Lipid Membranes.
abstract: Influenza A virus matrix protein 1 (M1) is an essential component involved in the structural stability of the virus and in the budding of new virions from infected cells. A deeper understanding of the molecular basis of virion formation and the budding process is required in order to devise new therapeutic approaches. We performed a detailed investigation of the interaction between M1 and phosphatidylserine (PS) (i.e., its main binding target at the plasma membrane [PM]), as well as the distribution of PS itself, both in model membranes and in living cells. To this end, we used a combination of techniques, including Förster resonance energy transfer (FRET), confocal microscopy imaging, raster image correlation spectroscopy, and number and brightness (N&B) analysis. Our results show that PS can cluster in segregated regions in the plane of the lipid bilayer, both in model bilayers constituted of PS and phosphatidylcholine and in living cells. The viral protein M1 interacts specifically with PS-enriched domains, and such interaction in turn affects its oligomerization process. Furthermore, M1 can stabilize PS domains, as observed in model membranes. For living cells, the presence of PS clusters is suggested by N&B experiments monitoring the clustering of the PS sensor lactadherin. Also, colocalization between M1 and a fluorescent PS probe suggest that, in infected cells, the matrix protein can specifically bind to the regions of PM in which PS is clustered. Taken together, our observations provide novel evidence regarding the role of PS-rich domains in tuning M1-lipid and M1-M1 interactions at the PM of infected cells.IMPORTANCEInfluenza virus particles assemble at the plasma membranes (PM) of infected cells. This process is orchestrated by the matrix protein M1, which interacts with membrane lipids while binding to the other proteins and genetic material of the virus. Despite its importance, the initial step in virus assembly (i.e., M1-lipid interaction) is still not well understood. In this work, we show that phosphatidylserine can form lipid domains in physical models of the inner leaflet of the PM. Furthermore, the spatial organization of PS in the plane of the bilayer modulates M1-M1 interactions. Finally, we show that PS domains appear to be present in the PM of living cells and that M1 seems to display a high affinity for them.
authors.affiliation: Institute for Biology, IRI Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.|Institute for Biochemistry and Biology, Potsdam Universität, Potsdam, Germany.
authors.forename: Sara
authors.initials: S
authors.lastname: Bobone
authors.affiliation: Institute for Biology, IRI Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
authors.forename: Malte
authors.initials: M
authors.lastname: Hilsch
authors.affiliation: Institute for Biology, IRI Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Storm
authors.affiliation: Institute for Biochemistry and Biology, Potsdam Universität, Potsdam, Germany.
authors.forename: Valentin
authors.initials: V
authors.lastname: Dunsing
authors.affiliation: Institute for Biology, IRI Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Herrmann
authors.affiliation: Institute for Biochemistry and Biology, Potsdam Universität, Potsdam, Germany chiantia@gmail.com.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Chiantia
mesh_terms: D000954:Antigens, Surface / Q000378:metabolism; D002460:Cell Line; D005453:Fluorescence; D057809:HEK293 Cells; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009980:Influenza A virus / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism; D018613:Microscopy, Confocal; D008894:Milk Proteins / Q000378:metabolism; D010718:Phosphatidylserines / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D014763:Viral Matrix Proteins / Q000737:chemistry / Q000378:metabolism*; D014771:Virion; D019065:Virus Assembly; D057074:Virus Release
chemical_list: D000954:Antigens, Surface; D008051:Lipid Bilayers; C098942:MFGE8 protein, human; D008563:Membrane Lipids; D008894:Milk Proteins; D010718:Phosphatidylserines; D014763:Viral Matrix Proteins
keywords: assembly; confocal microscopy; fluorescence image analysis; influenza; lipid rafts; matrix protein; model membranes; phosphatidylserine; plasma membrane