Mimicking the plant-cell interior under water stress by macromolecular crowding: disordered dehydrin proteins are highly resistant to structural collapse
2008 (English)In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 148, no 4, 1925-1937 p.Article in journal (Refereed) Published
The dehydrins are a class of drought-induced proteins in plants that lack a fixed three-dimensional structure. Their specific molecular action, as well as the reason for their disordered character, is as yet poorly understood. It has been speculated, however, that the dehydrins are tuned to acquire a biologically active structure only under the conditions at which they normally function, i.e. upon dehydration. To test this idea, we here investigate the effect of reduced water content and macromolecular crowding on three dehydrins from Arabidopsis thaliana. As a simplistic model for mimicking cellular dehydration we used polyethylene glycol (PEG), glycerol, and sugars which plants naturally employ as compatible solutes, i.e. sucrose and glucose. Macromolecular crowding was induced by the large polysaccharides ficoll and dextran. The results show that the dehydrins are remarkably stable in their disordered state and are only modestly affected by the solvent alterations. A notable exception is the dehydrin Cor47 which shows a small, intrinsic increase in helical structure at high concentrations of osmolytes. We also examined the effect of phosphorylation but found no evidence that such post-translational modifications of the dehydrin sequences modulate their structural response to osmolytes and crowding agents. The results suggest that the dehydrins are highly specialised proteins that have evolved to maintain their disordered character under conditions where unfolded states of several globular proteins would tend to collapse.
Place, publisher, year, edition, pages
2008. Vol. 148, no 4, 1925-1937 p.
dehydrin, intrinsically disordered protein, macromolecular crowding, circular dichroism (CD)
Research subject Biochemistry
IdentifiersURN: urn:nbn:se:su:diva-17653DOI: 10.1104/pp.108.124099ISI: 000261501500016OAI: oai:DiVA.org:su-17653DiVA: diva2:184174