TY  - JOUR
A1  - Hundertmark, Michaela
A1  - Dimova, Rumiana
A1  - Lengefeld, Jan
A1  - Seckler, Robert
A1  - Hincha, Dirk K.
T1  - The intrinsically disordered late embryogenesis abundant protein LEA18 from Arabidopsis thaliana modulates membrane stability through binding and folding.
N2  - 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 ;-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. Research Highlights
Y1  - 2011
SN  - 0006-3002
ER  - 
TY  - JOUR
A1  - Popova, Antoaneta V.
A1  - Hundertmark, Michaela
A1  - Seckler, Robert
A1  - Hincha, Dirk K.
T1  - Structural transitions in the intrinsically disordered plant dehydration stress protein LEA7 upon drying are modulated by the presence of membranes
JF  - Biochimica et biophysica acta : Biomembranes
N2  - Dehydration stress-related late embryogenesis abundant (LEA) proteins have been found in plants, invertebrates and bacteria. Most LEA proteins are unstructured in solution, but some fold into amphipathic a-helices during drying. The Pfam LEA_4 (Group 3) protein LEA7 from the higher plant Arabidopsis thaliana was predicted to be 87% alpha-helical, while CD spectroscopy showed it to be largely unstructured in solution and only 35% alpha-helical in the dry state. However, the dry protein contained 15% beta-sheets. FTIR spectroscopy revealed the (beta-sheets to be largely due to aggregation. beta-Sheet content was reduced and alpha-helix content increased when LEA7 was dried in the presence of liposomes with secondary structure apparently influenced by lipid composition. Secondary structure was also affected by the presence of membranes in the fully hydrated state. A temperature-induced increase in the flexibility of the dry protein was also only observed in the presence of membranes. Functional interactions of LEA7 with membranes in the dry state were indicated by its influence on the thermotropic phase transitions of the lipids and interactions with the lipid headgroup phosphates.
KW  - Desiccation
KW  - CD spectroscopy
KW  - FTIR spectroscopy
KW  - LEA protein
KW  - Protein-membrane interactions
KW  - Protein secondary structure
Y1  - 2011
U6  - https://doi.org/10.1016/j.bbamem.2011.03.009
SN  - 0005-2736
VL  - 1808
IS  - 7
SP  - 1879
EP  - 1887
PB  - Elsevier
CY  - Amsterdam
ER  -