Authors:	Ahlswede, Lena Siebenaller, Carmen Junglas, Benedikt Hellmann, Nadja Schneider, Dirk
Title:	Human Claudin-7 cis-interactions are not crucial for membrane-membrane (trans-) interactions
Online publication date:	26-Oct-2022
Year of first publication:	2022
Language:	english
Abstract:	Human Claudin-7 (Cldn7) is a member of the Claudin (Cldn) superfamily. In vivo, these proteins form tight junctions, which establish constricted connections between cells. Cldns oligomerize within the membrane plane (= cis-interaction), and also interact with Cldns from adjacent cells (= trans-interaction). Interactions of Cldns are typically studied in vivo and structural analyses of isolated Cldns are limited. Here, we describe heterologous expression in E. coli and purification of human Cldn7, enabling in vitro analyses of the isolated protein using detergent and model membrane systems. Cldn7 exists as a monomer, hexamer, and various higher oligomers in micelles. While only limited unfolding of the protein was observed in the presence of the anionic detergent sodium dodecyl sulfate, decreased ionic strength did affect Cldn7 cis-interactions. Furthermore, we identified two amino acids which mediate electrostatic cis-interactions and analyzed the impact of disturbed cis-interaction on trans-contacts via atomic force microscopy and monitoring Förster resonance energy transfer between fluorescently labeled Cldn7-containing proteoliposomes. Our results indicate that Cldn7 cis-oligomerization might not be a prerequisite for establishing trans-contacts.
DDC:	570 Biowissenschaften 570 Life sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-8174
Version:	Published version
Publication type:	Zeitschriftenaufsatz
Document type specification:	Scientific article
License:	CC BY
Information on rights of use:	https://creativecommons.org/licenses/by/4.0/
Journal:	Frontiers in molecular biosciences 9
Pages or article number:	908383
Publisher:	Frontiers Media
Publisher place:	Lausanne
Issue date:	2022
ISSN:	2296-889X
Publisher URL:	https://doi.org/10.3389/fmolb.2022.908383
Publisher DOI:	10.3389/fmolb.2022.908383
Appears in collections:	DFG-491381577-G