AFM visualization of mobile influenza A M2 molecules in planar bilayers.
We report the observation of influenza A M2 (M2) incorporated in a dipalmitoylphosphatidylcholine (DPPC) supported planar bilayer on mica, formed by use of a modified vesicle fusion method from proteoliposomes and visualized with contact mode atomic force microscopy. Incubation of proteoliposomes in a hyperosmotic solution and increased DPPC/M2 weight ratios improved supported planar bilayer formation by M2/DPPC proteoliposomes. M2's extra-bilayer domains were observed as particles estimated to protrude 1-1.5 nm above the bilayer surface and <4 nm in diameter. Particle density was 5-18% of the nominal tetramer density. Movement of observable M2 particles was independent of the probe tip. The mean lateral diffusion coefficient (D) of M2 was 4.4 +/- 1.0 x 10(-14) cm(2)/s. Eighty-two percent of observable particles were mobile on the observable timescale (D > 6 x 10(-15) cm(2)/s). Protein-protein interactions were also observed directly.
Hughes
Travis
T
Department of Physics and Astronomy, Brigham Young University, Provo, Utah, USA. Travis.Hughes@colorado.edu
Strongin
Bradley
B
Gao
Fei Philip
FP
Vijayvergiya
Viksita
V
Busath
David D
DD
Davis
Robert C
RC
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D009980:Influenza A virus / Q000737:chemistry*; D008051:Lipid Bilayers / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D009995:Osmosis; D011485:Protein Binding; D014763:Viral Matrix Proteins / Q000378:metabolism* / Q000648:ultrastructure; D000086082:Viroporin Proteins
D015060:1,2-Dipalmitoylphosphatidylcholine; D008051:Lipid Bilayers; D014763:Viral Matrix Proteins; C488937:M2 protein, Influenza A virus; D000086082:Viroporin Proteins