title: Tunable membrane binding of the intrinsically disordered dehydrin Lti30, a cold-induced plant stress protein.
abstract: 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.
authors.affiliation: Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: Sylvia K
authors.initials: SK
authors.lastname: Eriksson
authors.forename: Michael
authors.initials: M
authors.lastname: Kutzer
authors.forename: Jan
authors.initials: J
authors.lastname: Procek
authors.forename: Gerhard
authors.initials: G
authors.lastname: Gröbner
authors.forename: Pia
authors.initials: P
authors.lastname: Harryson
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002152:Calorimetry, Differential Scanning; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D057773:Cold Shock Proteins and Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D055672:Static Electricity; D020349:Surface Plasmon Resonance; D013696:Temperature; D020524:Thylakoids / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; D057773:Cold Shock Proteins and Peptides; D010743:Phospholipids; C090418:XERO2 protein, Arabidopsis