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

Navarro-Retamal, C., Bremer, A., Ingolfsson, H. I., Alzate-Morales, J., Caballero, J., Thalhammer, A., Gonzalez, W. & Hincha, D. K., 18-Sep-2018, In : Biophysical Journal. 115, 6, p. 968-980 13 p.

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  • Folding and Lipid Composition Determine Membrane Interaction

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  • Carlos Navarro-Retamal
  • Anne Bremer
  • Helgi I. Ingolfsson
  • Jans Alzate-Morales
  • Julio Caballero
  • Anja Thalhammer
  • Wendy Gonzalez
  • Dirk K. Hincha

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 alpha-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.

Original languageEnglish
Pages (from-to)968-980
Number of pages13
JournalBiophysical Journal
Volume115
Issue number6
Publication statusPublished - 18-Sep-2018

    Keywords

  • MOLECULAR-DYNAMICS SIMULATIONS, TRANSFORM INFRARED-SPECTROSCOPY, THERMOTROPIC PHASE-BEHAVIOR, PLANT COLD-ACCLIMATION, COARSE-GRAINED MODEL, MARTINI FORCE-FIELD, ALPHA-SYNUCLEIN, LEA PROTEINS, ARABIDOPSIS-THALIANA, FREEZING TOLERANCE

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