Browsing by Author "Hauß, T"

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    Intrinsically disordered stress protein COR15A resides at the membrane surface during dehydration
    (Biophysical Society, 2017-08-08) Bremer, A; Kent, B; Hauß, T; Thalhammer, A; Yepuri, NR; Darwish, TA; Garvey, CJ; Bryant, G; Hincha, DK
    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 α-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 α-helices already under mild dehydration conditions (97% relative humidity (RH), corresponding to freezing at −3°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 α-helix. © 2017 Biophysical Society - Open access
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    New sources and instrumentation for neutrons in biology
    (Elsevier, 2008-04-18) Teixeira, SCM; Zaccai, G; Ankner, J; Bellissent-Funel, MC; Bewley, RI; Blakeley, MP; Callow, P; Coates, L; Dahint, R; Dalgliesh, R; Dencher, NA; Forsyth, VT; Fragneto, G; Frick, B; Gilles, R; Gutberlet, T; Haertlein, M; Hauß, T; Häußler, W; Heller, WT; Herwig, K; Holderer, O; Juranyi, F; Kampmann, R; Knott, RB; Krueger, S; Langan, P; Lechner, RE; Lynn, GW; Majkrzak, CF; May, RP; Meilleur, F; Mo, Y; Mortensen, K; Myles, DAA; Natali, F; Neylon, C; Niimura, N; Ollivier, J; Ostermann, A; Peters, J; Pieper, J; Rühm, A; Schwahn, D; Shibata, K; Soper, AK; Strässle, T; Suzuki, J; Tanaka, I; Tehei, M; Timmins, P; Torikai, N; Unruh, T; Urban, V; Vavrin, R; Weiss, K
    Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed. © 2008, Elsevier Ltd.
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    Small molecule interactions with lipid bilayers by neutron diffraction
    (International Conference on Neutron Scattering, 2017-07-12) Garvey, CJ; Kent, B; Hauß, T; Georgii, R; Demé, B; Cristiglio, V; Darwish, TA; Wu, CM; Mancera, RL; Bryant, G
    While well established for studying the internal structure of bilayers and orientation of peptides and proteins with respect to bilayers, neutron lamellar diffraction is also a powerful tool for studying the average locus of solubilisation of small molecules in stacks of lipid bilayers. The approach has provided unique insights into important issues in anhydrobiology and cryobiology, where previously only molecular dynamics simulations (MD) had been able to provide molecular scale insights. Currently we use the methodology to understand the interaction of cryo-protectants with bilayers, with the aim of providing important validation of MD parameters to further enhance the utility of the method. Here we discuss the experimental approach, both in terms of the use of contrast variation and the use of selective deuteration to simplify the extraction of scattering length density profiles within the bilayer.