期刊
NATURE STRUCTURAL & MOLECULAR BIOLOGY
卷 27, 期 2, 页码 160-+出版社
NATURE PORTFOLIO
DOI: 10.1038/s41594-019-0371-2
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资金
- National Institutes of Health (NIH) [GM088204]
- NIH [P41GM111135]
The influenza B M2 (BM2) proton channel is activated by acidic pH to mediate virus uncoating. Unlike influenza A M2 (AM2), which conducts protons with strong inward rectification, BM2 conducts protons both inward and outward. Here we report 1.4- and 1.5-angstrom solid-state NMR structures of the transmembrane domain of the closed and open BM2 channels in a phospholipid environment. Upon activation, the transmembrane helices increase the tilt angle by 6 degrees and the average pore diameter enlarges by 2.1 angstrom. BM2 thus undergoes a scissor motion for activation, which differs from the alternating-access motion of AM2. These results indicate that asymmetric proton conduction requires a backbone hinge motion, whereas bidirectional conduction is achieved by a symmetric scissor motion. The proton-selective histidine and gating tryptophan in the open BM2 reorient on the microsecond timescale, similar to AM2, indicating that side chain dynamics are the essential driver of proton shuttling. Solid-state NMR structures of the influenza B M2 (BM2) proton channel transmembrane domain in a phospholipid environment reveal open and closed conformations and indicate that side chain dynamics are essential for proton shuttling by BM2.
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