Biophysical Society Conference | Tahoe 2022

Molecular Biophysics of Membranes

Poster Abstracts

25-POS Board 7 AMMONIA SELECTIVITY THROUGH AQUAPORIN ATTIP2;1 IN GEL PHASE LIPID BILAYER Deepak Kumar 1 ; Tomas Kubar 1 ; 1 Karlsruhe Institute of Technology, Institute of Physical Chemistry (IPC), Karlsruhe, Germany Aquaporins are highly efficient transmembrane protein channels that selectively, yet efficiently allow water and other small solutes to pass through lipid bilayer. Aquaporin AtTIP2;1 facilitates the permeation of water as well as ammonia across the vacuolar membrane of plants. Experimentally, it has been suggested that the selective filter region plays a pivotal role in the permeation of ammonia across the aquaporin. The main objective of this work is to study the permeabilities of water and ammonia through AtTIP2;1 in liquid and gel phase lipid by means of microsecond molecular dynamics simulation. Our simulations shows that all channels are open in either ways, in both phases of the lipid. The passage of ammonia across the channels are in the direction of the flow of the water. Whereas ammonia permeates through the channels in liquid phase lipid, that process is largely blocked in gel phase lipid, in agreement with experimental observations. Additionally, potentials of the mean force generated by means of extended sampling simulations for the permeation of water along the pore of the aquaporins in both lipid phases revealed a low barrier to the permeation, corroborating with the observed frequent permeation events.

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