Interdomain flexibility and pH-induced conformational changes of AcrA revealed by molecular dynamics simulations

The Journal of Physical Chemistry. B
Beibei WangWenning Wang

Abstract

The membrane fusion protein (MFP) AcrA is proposed to link the inner membrane transporter AcrB and outer membrane protein TolC, forming the tripartite AcrAB-TolC efflux pump, and was shown to be functionally indispensible. Structural and EPR studies showed that AcrA has high conformational flexibility and exhibited pH-induced conformational change. In this study, we built the complete structure of AcrA through homology modeling and performed atomistic simulations of AcrA at different pH values. It was shown that the conformational flexibility of AcrA originates from the motions of α-hairpin and MP domains. The conformational dynamics of AcrA is sensitive to specific point mutations and pH values. In agreement with the EPR experiments, the interdomain motions were restrained upon lowering pH from 7.0 to 5.0 in the simulations. It was found that the protonation/deprotonation of His285 underlies the pH-regulated conformational dynamics of AcrA by disturbing the local hydrogen bond interactions, suggesting that the changes of pH in the periplasm accompanying the drug efflux could act as a signal to trigger the action of AcrA, which undergoes reversible conformational rearrangement.

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Citations

Jan 28, 2014·Interdisciplinary Sciences, Computational Life Sciences·Nadine FischerChristian Kandt
Jun 16, 2015·Frontiers in Microbiology·Martyn F SymmonsVassiliy N Bavro
Jan 1, 2013·Computational and Structural Biotechnology Journal·Paolo RuggeroneChristian Kandt
Mar 12, 2015·Frontiers in Microbiology·Helen I ZgurskayaDavid Wolloscheck
Feb 17, 2015·BioMed Research International·Robert SchulzUlrich Kleinekathöfer
Jan 30, 2019·Biophysical Journal·Zbigniew M DarzynkiewiczHelen I Zgurskaya
Sep 14, 2019·ACS Infectious Diseases·Anthony J HazelJames C Gumbart

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