Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

The protein M2 from influenza is a tetrameric membrane protein with several roles in the viral life cycle. The transmembrane helix (TMH) of M2 has proton channel activity that is required for unpackaging the viral genome. Additionally a C-terminal juxtamembrane region includes an amphipathic helix (APH) important for virus budding and scission. The APH interacts with membranes and is required for M2 localization to the site of viral budding. As a step toward obtaining high resolution information on the structure and lipid interactions of the M2 APH, we sought to develop a fast tumbling bicelle system, which would make studies of M2 in a membrane-like environment by solution NMR possible. Since M2 is highly sensitive to the solubilizing environment, an M2 construct containing the APH was studied under micelle and bicelle conditions while maintaining the same detergent and lipid headgroup chemistry to facilitate interpretation of the spectroscopic results. The sequence from a human H1N1 "swine flu" isolate was used to design an M2 construct (swM2) similar in amino acid sequence to currently circulating viruses. Comparison of swM2 solubilized in either the diacyl detergent 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) or a mixture of DHPC and the lipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) (q = 0.4) indicated that the largest changes were a decrease in helicity at the N-terminus of the TMH and a decrease in dynamics for the juxtamembrane linker residues connecting the TMH and the APH. Whereas the linker region is very dynamic and the amide protons are rapidly exchanged with water protons in micelles, the dynamics and water exchange are largely suppressed in the presence of lipid. Chemical shift changes and relaxation measurements were consistent with an overall stabilization of the linker region, with only modest changes in conformation or environment of the APH itself. Such changes are consistent with differences observed in structures of M2 in lipid bilayers and detergent micelles, indicating that the bicelle system provides a more membrane-like environment.

Original publication

DOI

10.1021/bi401035m

Type

Journal article

Journal

Biochemistry

Publication Date

26/11/2013

Volume

52

Pages

8420 - 8429

Keywords

1,2-Dipalmitoylphosphatidylcholine, Cross-Linking Reagents, Emulsions, Influenza A Virus, H1N1 Subtype, Ion Channels, Lipid Bilayers, Micelles, Models, Molecular, Nuclear Magnetic Resonance, Biomolecular, Peptide Fragments, Phosphatidylcholines, Protein Conformation, Protein Engineering, Protein Interaction Domains and Motifs, Recombinant Proteins, Surface-Active Agents, Viral Matrix Proteins