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Membrane-Induced Folding of the Plant Stress Dehydrin Lti30
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
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Number of Authors: 5
2016 (English)In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 171, no 2, 932-943 p.Article in journal (Refereed) Published
Abstract [en]

Dehydrins are disordered proteins that are expressed in plants as a response to embryogenesis and water-related stress. The molecular function and structural action of the dehydrins are yet elusive, but increasing evidence points to a role in protecting the structure and functional dynamics of cell membranes. An intriguing example is the cold-induced dehydrin Lti30 that binds to membranes by its conserved K segments. Moreover, this binding can be regulated by pH and phosphorylation and shifts the membrane phase transition to lower temperatures, consistent with the protein's postulated function in cold stress. In this study, we reveal how the Lti30-membrane interplay works structurally at atomic level resolution in Arabidopsis (Arabidopsis thaliana). Nuclear magnetic resonance analysis suggests that negatively charged lipid head groups electrostatically capture the protein's disordered K segments, which locally fold up into a-helical segments on the membrane surface. Thus, Lti30 conforms to the general theme of structure-function relationships by folding upon binding, in spite of its disordered, atypically hydrophilic and repetitive sequence signatures. Moreover, the fixed and well-defined structure of the membrane-bound K segments suggests that dehydrins have the molecular prerequisites for higher level binding specificity and regulation, raising new questions about the complexity of their biological function.

Place, publisher, year, edition, pages
2016. Vol. 171, no 2, 932-943 p.
National Category
Biological Sciences
Research subject
Biochemistry
Identifiers
URN: urn:nbn:se:su:diva-133244DOI: 10.1104/pp.15.01531ISI: 000380699200015PubMedID: 27208263OAI: oai:DiVA.org:su-133244DiVA: diva2:963011
Available from: 2016-09-07 Created: 2016-09-05 Last updated: 2016-12-19Bibliographically 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)
Opponent
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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