The disordered plant dehydrin Lti30 protects the membrane during water-related stress by cross-linking lipids

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The disordered plant dehydrin Lti30 protects the membrane during water-related stress by cross-linking lipids
Title:
The disordered plant dehydrin Lti30 protects the membrane during water-related stress by cross-linking lipids
Journal Title:
Journal of Biological Chemistry
Publication Date:
28 February 2019
Citation:
J. Biol. Chem. 2019 294: 6468-. doi:10.1074/jbc.RA118.007163
Abstract:
Dehydrins are intrinsically disordered proteins, generally expressed in plants as a response to embryogenesis and water-related stress. Their suggested functions are in membrane stabilization and cell protection. All dehydrins contain at least one copy of the highly conserved K-segment, proposed to be a membrane-binding motif. The dehydrin Lti30 (Arabidopsis thaliana) is up-regulated during cold and drought stress conditions and comprises six K-segments, each with two adjacent histidines. Lti30 interacts with the membrane electrostatically via pH-dependent protonation of the histidines. In this work, we seek a molecular understanding of the membrane interaction mechanism of Lti30 by determining the diffusion and molecular organization of Lti30 on model membrane systems by imaging total internal reflection– fluorescence correlation spectroscopy (ITIR-FCS) and molecular dynamics (MD) simulations. The dependence of the diffusion coefficient explored by ITIR-FCS together with MD simulations yields insights into Lti30 binding, domain partitioning, and aggregation. The effect of Lti30 on membrane lipid diffusion was studied on fluorescently labeled supported lipid bilayers of different lipid compositions at mechanistically important pH conditions. In parallel, we compared the mode of diffusion for short individual K-segment peptides. The results indicate that Lti30 binds the lipid bilayer via electrostatics, which restricts the mobility of lipids and bound protein molecules. At low pH, Lti30 binding induced lipid microdomain formation as well as protein aggregation, which could be correlated with one another. Moreover, at physiological pH, Lti30 forms nanoscale aggregates when proximal to the membrane suggesting that Lti30 may protect the cell by “cross-linking” the membrane lipids.
License type:
PublisherCopyrights
Funding Info:
Description:
This research was originally published in the Journal of Biological Chemistry. Anjali Gupta, Jan K. Marzinek, Damien Jefferies, Peter J. Bond, Pia Harryson and Thorsten Wohland, The disordered plant dehydrin Lti30 protects the membrane during water-related stress by cross-linking lipids. J Biol Chem. 2019; Vol:6468-6482. © the American Society for Biochemistry and Molecular Biology
ISSN:
0021-9258
1083-351X
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