Cholesterol-Dependent Conformational Exchange of the C-Terminal Domain of the Influenza A M2 Protein. Biochemistry 2015 Dec 15;54(49):7157-67
Date
11/17/2015Pubmed ID
26569023Pubmed Central ID
PMC4734095DOI
10.1021/acs.biochem.5b01065Scopus ID
2-s2.0-84949947657 (requires institutional sign-in at Scopus site) 34 CitationsAbstract
The C-terminal amphipathic helix of the influenza A M2 protein plays a critical cholesterol-dependent role in viral budding. To provide atomic-level detail on the impact cholesterol has on the conformation of M2 protein, we spin-labeled sites right before and within the C-terminal amphipathic helix of the M2 protein. We studied the spin-labeled M2 proteins in membranes both with and without cholesterol. We used a multipronged site-directed spin-label electron paramagnetic resonance (SDSL-EPR) approach and collected data on line shapes, relaxation rates, accessibility of sites to the membrane, and distances between symmetry-related sites within the tetrameric protein. We demonstrate that the C-terminal amphipathic helix of M2 populates at least two conformations in POPC/POPG 4:1 bilayers. Furthermore, we show that the conformational state that becomes more populated in the presence of cholesterol is less dynamic, less membrane buried, and more tightly packed than the other state. Cholesterol-dependent changes in M2 could be attributed to the changes cholesterol induces in bilayer properties and/or direct binding of cholesterol to the protein. We propose a model consistent with all of our experimental data that suggests that the predominant conformation we observe in the presence of cholesterol is relevant for the understanding of viral budding.
Author List
Kim SS, Upshur MA, Saotome K, Sahu ID, McCarrick RM, Feix JB, Lorigan GA, Howard KPAuthor
Jimmy B. Feix PhD Professor in the Biophysics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
CholesterolInfluenza A virus
Membranes, Artificial
Models, Chemical
Phosphatidylcholines
Phosphatidylglycerols
Protein Structure, Secondary
Protein Structure, Tertiary
Viral Matrix Proteins
