PH-dependent conformational changes of KcsA tetramer and monomer probed by Raman spectroscopy

verfasst von

Ann Kathrin Kniggendorf, David Schmidt, Bernhard Roth, Oliver Plettenburg, Carsten Zeilinger

Abstract

KcsA is a tetrameric potassium channel formed out of four identical monomeric subunits used as a standard model for selective potassium transport and pH-dependent gating. Large conformational changes are reported for tetramer and monomer upon gating, and the response of the monomer being controversial with the two major studies partially contradicting each other. KcsA was analyzed as functional tetramers embedded in liposomes and as monomer subunits with confocal Raman microscopy under physiological conditions for the active and the closed channel state, using 532 nm excitation to avoid introducing conformational changes during the measurement. Channel function was confirmed using liposome flux assay. While the classic fingerprint region below 1800 rel. cm⁻¹ in the Raman spectrum of the tetramer was unaffected, the CH-stretching region between 2800 and 3200 rel. cm⁻¹ was found to be strongly affected by the conformation. No pH-dependency was observed in the Raman spectra of the monomer subunits, which closely resembled the Raman spectrum of the tetramer in its active conformation, indicating that the open conformation of the monomer and not the closed conformation as postulated may equal the relaxed state of the molecule.

Organisationseinheit(en)

Hannoversches Zentrum für Optische Technologien (HOT)
PhoenixD: Simulation, Fabrikation und Anwendung optischer Systeme
Zentrum für Biomolekulare Wirkstoffe (BMWZ)

Externe Organisation(en)

Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

Typ

Artikel

Journal

International Journal of Molecular Sciences

Band

20

ISSN

1661-6596

Publikationsdatum

01.06.2019

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Katalyse, Molekularbiologie, Spektroskopie, Angewandte Informatik, Physikalische und Theoretische Chemie, Organische Chemie, Anorganische Chemie

Elektronische Version(en)

https://doi.org/10.3390/ijms20112736 (Zugang: Offen)
https://doi.org/10.15488/5102 (Zugang: Offen)