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Activation pH and Gating Dynamics of Influenza A M2 Proton Channel Revealed by Single‐Molecule Spectroscopy
Author(s) -
Lin ChunWei,
Mensa Bruk,
BarniolXicota Marta,
DeGrado William F.,
Gai Feng
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201701874
Subject(s) - chemistry , proton , gating , biophysics , molecule , crystallography , transmembrane protein , chemical physics , nuclear magnetic resonance , physics , biochemistry , biology , organic chemistry , receptor , quantum mechanics
Abstract Because of its importance in viral replication, the M2 proton channel of the influenza A virus has been the focus of many studies. Although we now know a great deal about the structural architecture underlying its proton conduction function, we know little about its conformational dynamics, especially those controlling the rate of this action. Herein, we employ a single‐molecule fluorescence method to assess the dynamics of the inter‐helical channel motion of both full‐length M2 and the transmembrane domain of M2. The rate of this motion depends not only on the identity of the channel and membrane composition but also on the pH in a sigmoidal manner. For the full‐length M2 channel, the rate is increased from approximately 190 μs −1 at high pH to approximately 80 μs −1 at low pH, with a transition midpoint at pH 6.1. Because the latter value is within the range reported for the conducting p K a value of the His37 tetrad, we believe that this inter‐helical motion accompanies proton conduction.