Resolving the 3D spatial orientation of helix I in the closed state of the colicin E1 channel domain by FRET. Insights into the integration mechanism

Lugo, Miguel R.; Ho, Derek; Merrill, A. Rod

doi:10.1016/j.abb.2016.08.007

Cited by 2 publications

(1 citation statement)

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“…The X-ray crystallographic structure of the colicin E1 C-domain consists of 10 α-helices, in which helices VIII and IX are highly hydrophobic . A plethora of biophysical studies have been conducted on colicin E1, including fluorescence resonance energy transfer, , solid-state NMR spectroscopy, and molecular dynamics simulations . These investigations revealed key insights into the closed-channel state, where the hydrophobic helices VIII and IX insert into the nonpolar core of the lipid bilayer to form a hydrophobic hairpin, while the other eight helices are embedded in the membrane interfacial layer.…”

Section: Introductionmentioning

confidence: 99%

In Situ Electrochemical and PM-IRRAS Studies of Colicin E1 Ion Channels in the Floating Bilayer Lipid Membrane

Merrill

et al. 2019

Langmuir

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Colicin E1 is a channel-forming bacteriocin produced by certain E. coli cells in an effort to reduce competition from other bacterial strains. The colicin E1 channel domain was incorporated into a 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) floating bilayer situated on a 1-thio--D-glucose modified gold (111) surface. The electrochemical properties of the colicin E1 channel in the floating bilayer were measured by electrochemical impedance spectroscopy (EIS); the configuration and orientation of colicin E1 in the bilayer were determined by polarization-modulation-infrared-reflection absorption spectroscopy (PM-IRRAS). The EIS and IR results indicate that colicin E1 adopts a closed channel state at the positive transmembrane potential, leading to high membrane resistance and a large tilt This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright @ American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see: angle of -helices. When the transmembrane potential becomes negative, colicin E1 begins to insert into the lipid bilayer, corresponding to low membrane resistance and a low tilt angle of -helices. The insertion of colicin E1 into the lipid bilayer is driven by the negative transmembrane potential, and the ion channel open and closed states are potential reversible. The data in this report provide new insights into the voltagegated mechanism of colicin E1 ion channels in phospholipid bilayers and illustrate that the floating bilayer lipid membrane at the metal electrode surface is a robust platform to study membrane-active proteins and peptides in a quasi-natural environment.

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