Article
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Triplin: Mechanistic Basis for Voltage-Gating
Version 1
: Received: 23 June 2023 / Approved: 26 June 2023 / Online: 26 June 2023 (13:47:56 CEST)
A peer-reviewed article of this Preprint also exists.
Colombini, M.; Liu, P.; Dee, C. Triplin: Mechanistic Basis for Voltage Gating. Int. J. Mol. Sci. 2023, 24, 11473. Colombini, M.; Liu, P.; Dee, C. Triplin: Mechanistic Basis for Voltage Gating. Int. J. Mol. Sci. 2023, 24, 11473.
Abstract
The outer membrane of Gram-negative bacteria contains a variety of pore-forming structures collectively referred to as porins. Some of these are voltage-dependent, but weakly so, closing at high voltages. Triplin, a novel bacterial pore-former, is a three-pore structure, highly voltage dependent, with a complex gating process. The three pores close sequentially: pore 1 at positive potentials, 2 at negative and 3 at positive. A positive domain containing 14 positive charges (the voltage sensor) translocates through the membrane during the closing process and the translocation is proposed to take place by the domain entering the pore and thus blocking it resulting in the closed conformation. This mechanism of pore closure is supported by kinetic measurements that show that in the closing process the voltage sensor travels through most of the transmembrane voltage before reaching the energy barrier. Voltage-dependent blockage of the pores by polyarginine but not by a 500 fold higher concentrations of polylysine, is consistent with the model of pore closure, with the sensor consisting mainly of arginine residues, and with the presence, in each pore, of a complementary surface that serves as a binding site for the sensor.
Keywords
voltage dependence; voltage sensor; porin; prokaryote; kinetics; polyarginine; cooperativity; pore
Subject
Biology and Life Sciences, Biophysics
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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