Year: 2019
Type: article
Abstract: Influenza A and B viruses cause seasonal flu epidemics. The M2 protein of influenza B (BM2) is a membrane-embedded tetrameric proton channel that is essential for the viral lifecycle. BM2 is a functional analog of AM2 but shares only 24% sequence identity for the transmembrane (TM) domain. The structure and function of AM2, which is targeted by two antiviral drugs, have been well characterized. In comparison, much less is known about the structure of BM2 and no drug is so far available to inhibit this protein. Here we use solid-state NMR spectroscopy to investigate the conformation of BM2(1–51) in phospholipid bilayers at high pH, which corresponds to the closed state of the channel. Using 2D and 3D correlation NMR experiments, we resolved and assigned the13C and15N chemical shifts of 29 residues of the TM domain, which yielded backbone (φ, ψ) torsion angles. Residues 6–28 form a well-ordered α-helix, whereas residues 1–5 and 29–35 display chemical shifts that are indicative of random coil or β-sheet conformations. The length of the BM2-TM helix resembles that of AM2-TM, despite their markedly different amino acid sequences. In comparison, large15N chemical shift differences are observed between bilayer-bound BM2 and micelle-bound BM2, indicating that the TM helix conformation and the backbone hydrogen bonding in lipid bilayers differ from the micelle-bound conformation. Moreover, HNchemical shifts of micelle-bound BM2 lack the periodic trend expected for coiled coil helices, which disagree with the presence of a coiled coil structure in micelles. These results establish the basis for determining the full three-dimensional structure of the tetrameric BM2 to elucidate its proton-conduction mechanism.
Source: Scientific Reports
Institution: Massachusetts Institute of Technology
Language: English
Subfield: Epidemiology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $1,790
Funders: National Science Foundation, U.S. Department of Health and Human Services, National High Magnetic Field Laboratory, National Institutes of Health, National Institute of General Medical Sciences, National Institute of Allergy and Infectious Diseases, Division of Materials Research, High Magnetic Field Laboratory, Chinese Academy of Sciences, State of Florida
Awards: G1138554163, National High Magnetic Field Laboratory Renewal 2018-2022, G2336362177, Structures and Dynamics of Proton and Cation-Dependent Channels and Transporters, G354028113, G3560959519, G3816623069, G410635398, G5272545174, G5597825783, G6010147111, Solid-state NMR studies of the dynamic interactions of the influenza A M2 membrane protein with water, antiviral drugs, and the M1 protein
OpenAlex ID: W2919042205