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Tunable Membrane Binding of the Intrinsically Disordered Dehydrin Lti30, a Cold-Induced Plant Stress Protein
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
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2011 (English)In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 23, no 6, 2391-2404 p.Article in journal (Refereed) Published
Abstract [en]

Dehydrins are intrinsically disordered plant proteins whose expression is upregulated under conditions of desiccation and cold stress. Their molecular function in ensuring plant survival is not yet known, but several studies suggest their involvement in membrane stabilization. The dehydrins are characterized by a broad repertoire of conserved and repetitive sequences, out of which the archetypical K-segment has been implicated in membrane binding. To elucidate the molecular mechanism of these K-segments, we examined the interaction between lipid membranes and a dehydrin with a basic functional sequence composition: Lti30, comprising only K-segments. Our results show that Lti30 interacts electrostatically with vesicles of both zwitterionic (phosphatidyl choline) and negatively charged phospholipids (phosphatidyl glycerol, phosphatidyl serine, and phosphatidic acid) with a stronger binding to membranes with high negative surface potential. The membrane interaction lowers the temperature of the main lipid phase transition, consistent with Lti30's proposed role in cold tolerance. Moreover, the membrane binding promotes the assembly of lipid vesicles into large and easily distinguishable aggregates. Using these aggregates as binding markers, we identify three factors that regulate the lipid interaction of Lti30 in vitro: (1) a pH dependent His on/off switch, (2) phosphorylation by protein kinase C, and (3) reversal of membrane binding by proteolytic digest.

Place, publisher, year, edition, pages
2011. Vol. 23, no 6, 2391-2404 p.
National Category
Biological Sciences
Research subject
Biochemistry
Identifiers
URN: urn:nbn:se:su:diva-67573DOI: 10.1105/tpc.111.085183ISI: 000293224200028OAI: oai:DiVA.org:su-67573DiVA: diva2:470584
Note

authorCount :5

Available from: 2011-12-29 Created: 2011-12-29 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Molecular properties of disordered plant dehydrins: Membrane interaction and function in stress
Open this publication in new window or tab >>Molecular properties of disordered plant dehydrins: Membrane interaction and function in stress
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Dehydrins are intrinsically disordered plant stress-proteins. Repetitively in their sequence are some highly conserved stretches of 7-17 residues, the so called K-, S-, Y- and lysine rich segments. This thesis aims to give insight into the possible role dehydrins have in the stressed plant cell with main focus on membrane interaction and protection. The work includes four recombinant dehydrins from the plant Arabidopsis thaliana: Cor47 (SK3), Lti29 (SK3), Lti30 (K6) and Rab18 (Y2SK2).

Initially, we mimicked crowded cellular environment in vitro to verify that dehydrins are truly disordered proteins. Thereafter, the proposal that the compulsory K-segment determines membrane binding was tested. Experiments show that only Lti30 and Rab18 bind, whereas Cor47 and Lti29 does not. As Lti30 and Rab18 binds they assembles vesicles into clusters in vitro, a feature used to characterize the interaction. From this it was shown that membrane binding of Lti30 is electrostatic and determined by global as well as local charges. Protonation of histidine pairs flanking the K-segments works as an on/off-binding switch. By NMR studies it was shown that the K-segments form a dynamic α-helix upon binding, so called disorder-to-order behaviour. Also, dehydrins electrostatic interaction with lipids can be further tuned by posttranslational phosphorylation or coordination of calcium and zinc ions.

Finally, specific binding of Rab18 to inositol lipids, mainly PI(4,5)P2, is reported. The interaction is mainly coordinated by two arginines neighboring one of the K-segments. In conclusion, the K-segments are indeed involved in the binding of dehydrins to membrane but only in combination with extensions (Lti30) or modified (Rab18). 

Place, publisher, year, edition, pages
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2016. 62 p.
Keyword
abiotic stress, dehydrin, intrinsically disordered proteins, Lea-proteins, phospholipids
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
urn:nbn:se:su:diva-136033 (URN)978-91-7649-065-5 (ISBN)978-91-7649-599-5 (ISBN)
Public defence
2017-01-13, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
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Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.

Available from: 2016-12-20 Created: 2016-11-29 Last updated: 2016-12-21Bibliographically approved

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