TY  - JOUR
A1  - Bremer, Anne
A1  - Kent, Ben
A1  - Hauss, Thomas
A1  - Thalhammer, Anja
A1  - Yepuri, Nageshwar R.
A1  - Darwish, Tamim A.
A1  - Garvey, Christopher J.
A1  - Bryant, Gary
A1  - Hincha, Dirk K.
T1  - Intrinsically Disordered Stress Protein COR15A Resides at the Membrane Surface during Dehydration
JF  - Biophysical journal
N2  - Plants from temperate climate zones are able to increase their freezing tolerance during exposure to low, above zero temperatures in a process termed cold acclimation. During this process, several cold-regulated (COR) proteins are accumulated in the cells. One of them is COR15A, a small, intrinsically disordered protein that contributes to leaf freezing tolerance by stabilizing cellular membranes. The isolated protein folds into amphipathic a-helices in response to increased crowding conditions, such as high concentrations of glycerol. Although there is evidence for direct COR15A-membrane interactions, the orientation and depth of protein insertion were unknown. In addition, although folding due to high osmolyte concentrations had been established, the folding response of the protein under conditions of gradual dehydration had not been investigated. Here we show, using Fourier transform infrared spectroscopy, that COR15A starts to fold into a-helices already under mild dehydration conditions (97% relative humidity (RH), corresponding to freezing at -3 degrees C) and that folding gradually increases with decreasing RH. Neutron diffraction experiments at 97 and 75% RH established that the presence of COR15A had no significant influence on the structure of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membranes. However, using deuterated POPC we. could clearly establish that COR15A interacts with the membranes and penetrates below the headgroup region into the upper part of the fatty acyl chain region. This localization is in agreement with our hypothesis that COR15A-membrane interaction is at least, in part, driven by a hydrophobic interaction between the lipids and the hydrophobic face of the amphipathic protein alpha-helix.
Y1  - 2017
U6  - https://doi.org/10.1016/j.bpj.2017.06.027
SN  - 0006-3495
SN  - 1542-0086
VL  - 113
SP  - 572
EP  - 579
PB  - Cell Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Shou, Keyun
A1  - Bremer, Anne
A1  - Rindfleisch, Tobias
A1  - Knox-Brown, Patrick
A1  - Hirai, Mitsuhiro
A1  - Rekas, Agata
A1  - Garvey, Christopher J.
A1  - Hincha, Dirk K.
A1  - Stadler, Andreas M.
A1  - Thalhammer, Anja
T1  - Conformational selection of the intrinsically disordered plant stress protein COR15A in response to solution osmolarity - an X-ray and light scattering study
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - The plant stress protein COR15A stabilizes chloroplast membranes during freezing. COR15A is an intrinsically disordered protein (IDP) in aqueous solution, but acquires an alpha-helical structure during dehydration or the increase of solution osmolarity. We have used small- and wide-angle X-ray scattering (SAXS/WAXS) combined with static and dynamic light scattering (SLS/DLS) to investigate the structural and hydrodynamic properties of COR15A in response to increasing solution osmolarity. Coarse-grained ensemble modelling allowed a structure-based interpretation of the SAXS data. Our results demonstrate that COR15A behaves as a biomacromolecule with polymer-like properties which strongly depend on solution osmolarity. Biomacromolecular self-assembly occurring at high solvent osmolarity is initiated by the occurrence of two specific structural subpopulations of the COR15A monomer. The osmolarity dependent structural selection mechanism is an elegant way for conformational regulation and assembly of COR15A. It highlights the importance of the polymer-like properties of IDPs for their associated biological function.
Y1  - 2019
U6  - https://doi.org/10.1039/c9cp01768b
SN  - 1463-9076
SN  - 1463-9084
VL  - 21
IS  - 34
SP  - 18727
EP  - 18740
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -