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Biophys J. 2018 Sep 18;115(6):968-980. doi: 10.1016/j.bpj.2018.08.014. Epub 2018 Aug 18.

Folding and Lipid Composition Determine Membrane Interaction of the Disordered Protein COR15A.

Author information

1
Center for Bioinformatics and Molecular Simulations, Universidad de Talca, Casilla, Talca, Chile.
2
Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam, Germany.
3
Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, AG Groningen, The Netherlands.
4
Physikalische Biochemie, Universität Potsdam, Potsdam, Germany.
5
Center for Bioinformatics and Molecular Simulations, Universidad de Talca, Casilla, Talca, Chile; Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Talca, Casilla, Talca, Chile.
6
Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam, Germany. Electronic address: hincha@mpimp-golm.mpg.de.

Abstract

Plants from temperate climates, such as the model plant Arabidopsis thaliana, are challenged with seasonal low temperatures that lead to increased freezing tolerance in fall in a process termed cold acclimation. Among other adaptations, this involves the accumulation of cold-regulated (COR) proteins, such as the intrinsically disordered chloroplast-localized protein COR15A. Together with its close homolog COR15B, it stabilizes chloroplast membranes during freezing. COR15A folds into amphipathic α-helices in the presence of high concentrations of low-molecular-mass crowders or upon dehydration. Under these conditions, the (partially) folded protein binds peripherally to membranes. In our study, we have used coarse-grained molecular dynamics simulations to elucidate the details of COR15A-membrane binding and its effects on membrane structure and dynamics. Simulation results indicate that at least partial folding of COR15A and the presence of highly unsaturated galactolipids in the membranes are necessary for efficient membrane binding. The bound protein is stabilized on the membrane by interactions of charged and polar amino acids with galactolipid headgroups and by interactions of hydrophobic amino acids with the upper part of the fatty acyl chains. Experimentally, the presence of liposomes made from a mixture of lipids mimicking chloroplast membranes induces additional folding in COR15A under conditions of partial dehydration, in agreement with the simulation results.

PMID:
30195939
PMCID:
PMC6139882
DOI:
10.1016/j.bpj.2018.08.014

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