The intrinsically disordered late embryogenesis abundant protein LEA18 from Arabidopsis thaliana modulates membrane stability through binding and folding

• Published in: Biochimica et biophysica acta Vol. 1808; no. 1; pp. 446 - 453
• Main Authors: Hundertmark, Michaela, Dimova, Rumiana, Lengefeld, Jan, Seckler, Robert, Hincha, Dirk K.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2011
• Subjects: Arabidopsis - genetics; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Biophysics - methods; Calorimetry - methods; Electrophoresis, Polyacrylamide Gel; Intrinsically disordered protein; Late embryogenesis abundant protein; Liposomes - chemistry; Membrane stability; Particle Size; Plant Physiological Phenomena; Protein Binding; Protein Conformation; Protein Folding; Protein Structure, Secondary; Protein–membrane interaction; Recombinant Proteins - chemistry; Time Factors; CD; Membrane stability; CF; LEA; NBD-PE; Protein–membrane interaction; Late embryogenesis abundant protein; IDP; Protein folding; POPC; ITC; FRET; MBP; EPE; Intrinsically disordered protein; EPG; Rh-PE
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2010.09.010

Intrinsically disordered proteins (IDPs) constitute a substantial part of cellular proteomes. Late embryogenesis abundant (LEA) proteins are mostly predicted to be IDPs associated with dehydration tolerance in many plant, animal and bacterial species. Their functions, however, are largely unexplored and also their structure and interactions with potential target molecules have only recently been experimentally investigated in a small number of proteins. Here, we report on the structure and interactions with membranes of the Pfam LEA_1 protein LEA18 from the higher plant Arabidopsis thaliana. This functionally uncharacterized positively charged protein specifically aggregated and destabilized negatively charged liposomes. Isothermal titration calorimetry showed binding of the protein to both charged and uncharged membranes. LEA18 alone was largely unstructured in solution. While uncharged membranes had no influence on the secondary structure of LEA18, the protein partially folded into β-sheet structure in the presence of negatively charged liposomes. These data suggest that LEA18 does not function as a membrane stabilizing protein, as suggested for other LEA proteins. Instead, a possible function of LEA18 could be the composition-dependent modulation of membrane stability, e.g., during signaling or vesicle-mediated transport. ►LEA18 is a plant IDP that induces leakage from liposomes during freezing. ►In solution only negatively charged membranes are destabilized and aggregated. ►Binding to negatively charged membranes induces partial folding in LEA18. ►ITC data show strong binding to negatively charged and weak binding to neutral lipids.