@misc{SowemimoKnoxBrownBorcherdsetal.2019,
  author    = {Sowemimo, Oluwakemi T. and Knox-Brown, Patrick and Borcherds, Wade and Rindfleisch, Tobias and Thalhammer, Anja and Daughdrill, Gary W.},
  title     = {Conserved glycines control disorder and function in the cold-regulated protein, COR15A},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1089},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-47221},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-472217},
  pages     = {19},
  year      = {2019},
  abstract  = {Cold-regulated (COR) 15A is an intrinsically disordered protein (IDP) from Arabidopsis thaliana important for freezing tolerance. During freezing-induced cellular dehydration, COR15A transitions from a disordered to mostly alpha-helical structure. We tested whether mutations that increase the helicity of COR15A also increase its protective function. Conserved glycine residues were identified and mutated to alanine. Nuclear magnetic resonance (NMR) spectroscopy was used to identify residue-specific changes in helicity for wildtype (WT) COR15A and the mutants. Circular dichroism (CD) spectroscopy was used to monitor the coil-helix transition in response to increasing concentrations of trifluoroethanol (TFE) and ethylene glycol. The impact of the COR15A mutants on the stability of model membranes during a freeze-thaw cycle was investigated by fluorescence spectroscopy. The results of these experiments showed the mutants had a higher content of alpha-helical structure and the increased alpha-helicity improved membrane stabilization during freezing. Comparison of the TFE- and ethylene glycol-induced coil-helix transitions support our conclusion that increasing the transient helicity of COR15A in aqueous solution increases its ability to stabilize membranes during freezing. Altogether, our results suggest the conserved glycine residues are important for maintaining the disordered structure of COR15A but are also compatible with the formation of alpha-helical structure during freezing induced dehydration.},
  language  = {en}
}
@misc{SowemimoBorcherdsKnoxBrownetal.2019,
  author    = {Sowemimo, Oluwakemi and Borcherds, Wade and Knox-Brown, Patrick and Rindfleisch, Tobias and Thalhammer, Anja and Daughdrill, Gary},
  title     = {Evolution of Transient Helicity and Disorder in Late Embryogenesis Abundant Protein COR15A},
  series = {Biophysical journal},
  volume    = {116},
  journal   = {Biophysical journal},
  number    = {3},
  publisher = {Cell Press},
  address   = {Cambridge},
  issn      = {0006-3495},
  doi       = {10.1016/j.bpj.2018.11.2553},
  pages     = {473A -- 473A},
  year      = {2019},
  abstract  = {Cold regulated protein 15A (COR15A) is a nuclear encoded, intrinsically disordered protein that is found in Arabidopsis thaliana. It belongs to the Late Embryogenesis Abundant (LEA) family of proteins and is responsible for increased freezing tolerance in plants. COR15A is intrinsically disordered in dilute solutions and adopts a helical structure upon dehydration or in the presence of co-solutes such as TFE and ethylene glycol. This helical structure is thought to be important for protecting plants from dehydration induced by freezing. Multiple protein sequence alignments revealed the presence of several conserved glycine residues that we hypothesize keeps COR15A from becoming helical in dilute solutions. Using AGADIR, the change in helical content of COR15A when these conserved glycine residues were mutated to alanine residues was predicted. Based on the predictions, glycine to alanine mutants were made at position 68, and 54,68,81, and 84. Labeled samples of wildtype COR15A and mutant proteins were purified and NMR experiments were performed to examine any structural changes induced by the mutations. To test the effects of dehydration on the structure of COR15A, trifluoroethanol, an alcohol based co solvent that is proposed to induce/stabilize helical structure in peptides was added to the NMR samples, and the results of the experiment showed an increase in helical content, compared to the samples without TFE. To test the functional differences between wild type and the mutants, liposome leakage assays were performed. The results from these assays suggest the more helical mutants may augment membrane stability.},
  language  = {en}
}
@article{SowemimoKnoxBrownBorcherdsetal.2019,
  author    = {Sowemimo, Oluwakemi T. and Knox-Brown, Patrick and Borcherds, Wade and Rindfleisch, Tobias and Thalhammer, Anja and Daughdrill, Gary W.},
  title     = {Conserved Glycines Control Disorder and Function in the Cold-Regulated Protein, COR15A},
  series = {Biomolecules},
  volume    = {9},
  journal   = {Biomolecules},
  number    = {3},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2218-273X},
  doi       = {10.3390/biom9030084},
  pages     = {17},
  year      = {2019},
  abstract  = {Cold-regulated (COR) 15A is an intrinsically disordered protein (IDP) from Arabidopsis thaliana important for freezing tolerance. During freezing-induced cellular dehydration, COR15A transitions from a disordered to mostly alpha-helical structure. We tested whether mutations that increase the helicity of COR15A also increase its protective function. Conserved glycine residues were identified and mutated to alanine. Nuclear magnetic resonance (NMR) spectroscopy was used to identify residue-specific changes in helicity for wildtype (WT) COR15A and the mutants. Circular dichroism (CD) spectroscopy was used to monitor the coil-helix transition in response to increasing concentrations of trifluoroethanol (TFE) and ethylene glycol. The impact of the COR15A mutants on the stability of model membranes during a freeze-thaw cycle was investigated by fluorescence spectroscopy. The results of these experiments showed the mutants had a higher content of alpha-helical structure and the increased alpha-helicity improved membrane stabilization during freezing. Comparison of the TFE- and ethylene glycol-induced coil-helix transitions support our conclusion that increasing the transient helicity of COR15A in aqueous solution increases its ability to stabilize membranes during freezing. Altogether, our results suggest the conserved glycine residues are important for maintaining the disordered structure of COR15A but are also compatible with the formation of alpha-helical structure during freezing induced dehydration.},
  language  = {en}
}