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

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

Dehydrins are intrinsically disordered proteins, generally expressed in plants as a response to embryogenesis and waterrelated 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 withMDsimulations 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.

0021-9258
6468-6482
Gupta, Anjali
21d25dce-1320-4d3a-9174-3ce1b76ed228
Marzinek, Jan K.
64e75d21-98b8-44d8-96f7-5076859e13ec
Jefferies, Damien
8df97e21-8df6-4571-bfbe-3edc41e16967
Bond, Peter J.
08f46940-85e8-44c4-a368-d94342a10fd6
Harryson, Pia
2eb9cb80-c88a-4b64-8ed9-a753a9d844fc
Wohland, Thorsten
5d1071c9-69bb-4d34-94c1-56f039e77d2a
Gupta, Anjali
21d25dce-1320-4d3a-9174-3ce1b76ed228
Marzinek, Jan K.
64e75d21-98b8-44d8-96f7-5076859e13ec
Jefferies, Damien
8df97e21-8df6-4571-bfbe-3edc41e16967
Bond, Peter J.
08f46940-85e8-44c4-a368-d94342a10fd6
Harryson, Pia
2eb9cb80-c88a-4b64-8ed9-a753a9d844fc
Wohland, Thorsten
5d1071c9-69bb-4d34-94c1-56f039e77d2a

Gupta, Anjali, Marzinek, Jan K., Jefferies, Damien, Bond, Peter J., Harryson, Pia and Wohland, Thorsten (2019) The disordered plant dehydrin Lti30 protects the membrane during water-related stress by cross-linking lipids. Journal of Biological Chemistry, 294 (16), 6468-6482. (doi:10.1074/jbc.RA118.007163).

Record type: Article

Abstract

Dehydrins are intrinsically disordered proteins, generally expressed in plants as a response to embryogenesis and waterrelated 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 withMDsimulations 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.

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More information

Accepted/In Press date: 14 December 2018
e-pub ahead of print date: 28 February 2019
Published date: 19 April 2019

Identifiers

Local EPrints ID: 431260
URI: http://eprints.soton.ac.uk/id/eprint/431260
ISSN: 0021-9258
PURE UUID: 5c3b5010-ce17-48e6-b629-f17c2c2f1c8e

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Date deposited: 29 May 2019 16:30
Last modified: 07 Oct 2020 01:07

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Contributors

Author: Anjali Gupta
Author: Jan K. Marzinek
Author: Damien Jefferies
Author: Peter J. Bond
Author: Pia Harryson
Author: Thorsten Wohland

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