@phdthesis{Hundertmark2008,
  author    = {Hundertmark, Michaela},
  title     = {Characterization of LEA genes and proteins from Arabidopsis thaliana (L.)},
  pages     = {VI, 135 S.},
  year      = {2008},
  language  = {en}
}
@article{ThalhammerHundertmarkPopovaetal.2010,
  author    = {Thalhammer, Anja and Hundertmark, Michaela and Popova, Antoaneta V. and Seckler, Robert and Hincha, Dirk K.},
  title     = {Interaction of two intrinsically disordered plant stress proteins (COR15A and COR15B) with lipid membranes in the dry state},
  issn      = {0005-2736},
  doi       = {10.1016/j.bbamem.2010.05.015},
  year      = {2010},
  abstract  = {COR15A and COR15B form a tandem repeat of highly homologous genes in Arabidopsis thaliana. Both genes are highly cold induced and the encoded proteins belong to the Pfam LEA_4 group (group 3) of the late embryogenesis abundant (LEA) proteins. Both proteins were predicted to be intrinsically disordered in solution. Only COR15A has previously been characterized and it was shown to be localized in the soluble stroma fraction of chloroplasts. Ectopic expression of COR15A in Arabidopsis resulted in increased freezing tolerance of both chloroplasts after freezing and thawing of intact leaves and of isolated protoplasts frozen and thawed in vitro. In the present study we have generated recombinant mature COR15A and COR15B for a comparative study of their structure and possible function as membrane protectants. CD spectroscopy showed that both proteins are predominantly unstructured in solution and mainly a-helical after drying. Both proteins showed similar effects on the thermotropic phase behavior of dry liposomes. A decrease in the gel to liquid-crystalline phase transition temperature depended on both the unsaturation of the fatty acyl chains and lipid headgroup structure. FTIR spectroscopy indicated no strong interactions between the proteins and the lipid phosphate and carbonyl groups, but significant interactions with the galactose headgroup of the chloroplast lipid monogalactosyldiacylglycerol. These findings were rationalized by modeling the secondary structure of COR15A and COR15B. Helical wheel projection indicated the presence of amphipathic a-helices in both proteins. The helices lacked a clear separation of positive and negative charges on the hydrophilic face, but contained several hydroxylated amino acids.},
  language  = {en}
}
@article{HundertmarkDimovaLengefeldetal.2011,
  author    = {Hundertmark, Michaela and Dimova, Rumiana and Lengefeld, Jan and Seckler, Robert and Hincha, Dirk K.},
  title     = {The intrinsically disordered late embryogenesis abundant protein LEA18 from Arabidopsis thaliana modulates membrane stability through binding and folding.},
  issn      = {0006-3002},
  year      = {2011},
  abstract  = {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},
  language  = {en}
}
@article{PopovaHundertmarkSeckleretal.2011,
  author    = {Popova, Antoaneta V. and Hundertmark, Michaela and Seckler, Robert and Hincha, Dirk K.},
  title     = {Structural transitions in the intrinsically disordered plant dehydration stress protein LEA7 upon drying are modulated by the presence of membranes},
  series = {Biochimica et biophysica acta : Biomembranes},
  volume    = {1808},
  journal   = {Biochimica et biophysica acta : Biomembranes},
  number    = {7},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0005-2736},
  doi       = {10.1016/j.bbamem.2011.03.009},
  pages     = {1879 -- 1887},
  year      = {2011},
  abstract  = {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.},
  language  = {en}
}
@article{HundertmarkDimovaLengefeldetal.2011,
  author    = {Hundertmark, Michaela and Dimova, Rumiana and Lengefeld, Jan and Seckler, Robert and Hincha, Dirk K.},
  title     = {The intrinsically disordered late embryogenesis abundant protein LEA18 from Arabidopsis thaliana modulates membrane stability through binding and folding},
  series = {Biochimica et biophysica acta : Biomembranes},
  volume    = {1808},
  journal   = {Biochimica et biophysica acta : Biomembranes},
  number    = {1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0005-2736},
  doi       = {10.1016/j.bbamem.2010.09.010},
  pages     = {446 -- 453},
  year      = {2011},
  abstract  = {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 beta-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.},
  language  = {en}
}
@article{HundertmarkPopovaRauschetal.2012,
  author    = {Hundertmark, Michaela and Popova, Antoaneta V. and Rausch, Saskia and Seckler, Robert and Hincha, Dirk K.},
  title     = {Influence of drying on the secondary structure of intrinsically disordered and globular proteins},
  series = {Biochemical and biophysical research communications},
  volume    = {417},
  journal   = {Biochemical and biophysical research communications},
  number    = {1},
  publisher = {Elsevier},
  address   = {San Diego},
  issn      = {0006-291X},
  doi       = {10.1016/j.bbrc.2011.11.067},
  pages     = {122 -- 128},
  year      = {2012},
  abstract  = {Circular dichroism (CD) spectroscopy of five Arabidopsis late embryogenesis abundant (LEA) proteins constituting the plant specific families LEA_5 and LEA_6 showed that they are intrinsically disordered in solution and partially fold during drying. Structural predictions were comparable to these results for hydrated LEA_6, but not for LEA_5 proteins. FTIR spectroscopy showed that verbascose, but not sucrose, strongly affected the structure of the dry proteins. The four investigated globular proteins were only mildly affected by drying in the absence, but strongly in the presence of sugars. These data highlight the larger structural flexibility of disordered compared to globular proteins and the impact of sugars on the structure of both disordered and globular proteins during drying.},
  language  = {en}
}