Conformation and Trimer Association of the Transmembrane Domain of the Parainfluenza Virus Fusion Protein in Lipid Bilayers from Solid-State NMR: Insights into the Sequence Determinants of Trimer Structure and Fusion Activity. Issue 5 (2nd March 2018)

• Record Type: Journal Article
• Authors: Lee, Myungwoon; Yao, Hongwei; Kwon, Byungsu; Waring, Alan J.; Ruchala, Peter; Singh, Chandan; Hong, Mei
• Is Part Of: Journal of molecular biology. Volume 430:Issue 5(2018)
• Page Start: 695
• Page End: 709
• Publication Date: 2018-03-02
• Subjects: magic-angle-spinning NMR -- trimer formation -- conformational plasticity -- spin diffusion; TMD transmembrane domain -- PIV5 parainfluenza virus 5 -- FP fusion peptide -- CODEX Centerband-Only Detection of Exchange -- magic angle spinning MAS; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2018.01.002
• Languages: English
• ISSNs: 0022-2836

Abstract

Abstract: Enveloped viruses enter cells by using their fusion proteins to merge the virus lipid envelope and the cell membrane. While crystal structures of the water-soluble ectodomains of many viral fusion proteins have been determined, the structure and assembly of the C-terminal transmembrane domain (TMD) remains poorly understood. Here we use solid-state NMR to determine the backbone conformation and oligomeric structure of the TMD of the parainfluenza virus 5 fusion protein. 13 C chemical shifts indicate that the central leucine-rich segment of the TMD is α-helical in POPC/cholesterol membranes and POPE membranes, while the Ile- and Val-rich termini shift to the β-strand conformation in the POPE membrane. Importantly, lipid mixing assays indicate that the TMD is more fusogenic in the POPE membrane than in the POPC/cholesterol membrane, indicating that the β-strand conformation is important for fusion by inducing membrane curvature. Incorporation of para-fluorinated Phe at three positions of the α-helical core allowed us to measure interhelical distances using 19 F spin diffusion NMR. The data indicate that, at peptide:lipid molar ratios of ~ 1:15, the TMD forms a trimeric helical bundle with inter-helical distances of 8.2–8.4 Å for L493F and L504F and 10.5 Å for L500F. These data provide high-resolution evidence of trimer formation of a viral fusion protein TMD in phospholipid bilayers, and indicate that the parainfluenza virus 5 fusion protein TMD harbors two functions: the central α-helical core is the trimerization unit of the protein, while the two termini are responsible for inducing membrane curvature by transitioning to a β-sheet conformation. Graphical Abstract: Unlabelled Image Highlights: A viral fusion protein transmembrane domain adopts β-sheet structure at the two termini. The β-sheet structure correlates with fusion activity. The central portion of the transmembrane domain forms an α-helical trimer whose structure is the same between lamellar and negative-curvature membranes. 19 F NMR yields interhelical distances that constrain the trimer structure.