title: Mechanism of influenza A M2 transmembrane domain assembly in lipid membranes.
abstract: M2 from influenza A virus functions as an oligomeric proton channel essential for the viral cycle, hence it is a high-priority pharmacological target whose structure and functions require better understanding. We studied the mechanism of M2 transmembrane domain (M2TMD) assembly in lipid membranes by the powerful biophysical technique of double electron-electron resonance (DEER) spectroscopy. By varying the M2TMD-to-lipid molar ratio over a wide range from 1:18,800 to 1:160, we found that M2TMD exists as monomers, dimers, and tetramers whose relative populations shift to tetramers with the increase of peptide-to-lipid (P/L) molar ratio. Our results strongly support the tandem mechanism of M2 assembly that is monomers-to-dimer then dimers-to-tetramer, since tight dimers are abundant at small P/L's, and thereafter they assemble as dimers of dimers in weaker tetramers. The stepwise mechanism found for a single-pass membrane protein oligomeric assembly should contribute to the knowledge of the association steps in membrane protein folding.
authors.affiliation: 1] Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 [2] National Biomedical Center for Advanced ESR Technology, Cornell University, Ithaca, NY 14853.
authors.forename: Elka R
authors.initials: ER
authors.lastname: Georgieva
authors.affiliation: 1] Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 [2] National Biomedical Center for Advanced ESR Technology, Cornell University, Ithaca, NY 14853.
authors.forename: Peter P
authors.initials: PP
authors.lastname: Borbat
authors.affiliation: School of Engineering, Cornell University, Ithaca, NY 14853.
authors.forename: Haley D
authors.initials: HD
authors.lastname: Norman
authors.affiliation: 1] Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 [2] National Biomedical Center for Advanced ESR Technology, Cornell University, Ithaca, NY 14853.
authors.forename: Jack H
authors.initials: JH
authors.lastname: Freed
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009980:Influenza A virus / Q000378:metabolism*; D008051:Lipid Bilayers / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D014763:Viral Matrix Proteins / Q000737:chemistry / Q000378:metabolism*; D000086082:Viroporin Proteins
chemical_list: D008051:Lipid Bilayers; D008563:Membrane Lipids; D010455:Peptides; D014763:Viral Matrix Proteins; C488937:M2 protein, Influenza A virus; D000086082:Viroporin Proteins