Characterization of the L.lambda. phase in trehalose-stabilized dry membranes by solid-state NMR and x-ray diffraction

Abstract

Solid-state nuclear magnetic resonance (NMR) spectroscopy and X-ray powder diffraction were used to investigate the mechanism of trehalose (TRE) stabilization of lipid bilayers. Calorimetric investigation of dry TRE-stabilized bilayers reveals a first-order phase transition (L kappa----L lambda) at temperatures similar to the L beta'----(P beta')----L alpha transition of hydrated lipid bilayers. X-ray diffraction studies show that dry mixtures of TRE and 1,2-dipalmitoyl-sn-phosphatidylcholine (DPPC) have a lamellar structure with excess crystalline TRE being present. The L kappa phase shows typical gel-phase X-ray diffraction patterns. In contrast, the L lambda-phase diffraction patterns indicate disordered hydrocarbon chains. 2H NMR of specifically 2H chain-labeled DPPC confirmed that the acyl chains are disordered in the L lambda phase over their entire lengths. 2H spectra of the choline headgroup show hindered molecular motions as compared to dry DPPC alone, and 13C spectra of the sn-2-carbonyl show rigid lattice powder patterns indicating very little motion at the headgroup and interfacial regions. Thus, the sugar interacts extensively with the hydrophilic regions of the lipid, from the choline and the phosphate moieties in the headgroup to the glycerol and carbonyls in the interfacial region. We postulate that the sugar and the lipid form an extensive hydrogen-bonded network with the sugar acting as a spacer to expand the distance between lipids in the bilayer. The fluidity of the hydrophobic region in the L lambda phase together with the bilayer stabilization at the headgroup contributes to membrane viability in anhydrobiotic organisms.

Trehalose-protected lipid membranes for determining membrane protein structure and insertion

“…2) indicate that at the highest temperature at which the lipid headgroups are rigid, the chains in the hydrated membrane are frozen (233 K) while the chains in the TRE-POPC membrane remain partly mobile (263 K). The deferred freezing of the acyl chains compared to the headgroup was also observed in TRE-DPPC membrane [6]. At the same temperature, the lipid chain dynamics is similar between the hydrated and the trehalose-protected POPC membranes, as seen, for example, in the 2 H spectra at 263 K (Fig.…”

“…We show here that trehalose-containing dry lipid membranes preserve the lipid bilayer structure while removing the headgroup and glycerol backbone motions at higher temperatures than the hydrated membranes, thus facilitating the measurement of protein-lipid distances. While the phase properties of trehalose-DPPC mixtures had been investigated by NMR before [6,7], a comparison of the conformation of the hydrated and trehalose-containing membranes for protein structure determination has not been reported.…”

Membrane-dependent oligomeric structure and pore formation of a β-hairpin antimicrobial peptide in lipid bilayers from solid-state NMR

“…Trehalose preserves the lameller structure of dry membranes in the absence of water by replacing the hydration water around the lipid headgroups (48). Small amounts of trehalose raise the phase-transition temperature of the membrane compared with the hydrated bilayer, thus reducing lipid motion (49) and allowing the CODEX experiments to be conducted at milder temperatures (M.T., unpublished data). Experiments on hydrated and trehalose-containing POPC͞PG-1 membranes confirmed that the oligomeric state of PG-1 is the same between the two.…”

Salt tolerance of Microcoleus vaginatus Gom., a cyanobacterium isolated from desert algal crust, was enhanced by exogenous carbohydrates

“…As known, sucrose does not undergo Millard reactions with the amino groups of proteins, as one of the non-reducing sugars it mainly accumulates as storage or regulatory solute in response to stress (Lee et al, 1989;Page-Sharp et al, 1999). The EPS layer surrounding cells creates a microenvironment that buffers the osmotic disequilibrium across the cell membrane preserving hypersaline conditions in marine algae (Liu and Buskey, 2000).…”