Disaccharides Impact the Lateral Organization of Lipid Membranes

Disaccharides are well known for their membrane protective ability. Interaction between sugars and multi-component membranes, however, remains largely unexplored. Here, we combine molecular dynamics simulations and fluorescence microscopy to study the effect of mono- and disaccharides on membranes that phase separate into Lo and Ld domains. We find that non-reducing disaccharides, sucrose and trehalose, strongly destabilize the phase separation leading to uniformly mixed membranes as opposed to monosaccharides and reducing disaccharides. To unveil the driving force for this process, simulations were performed in which the sugar linkage was artificially modified. The availability of accessible interfacial binding sites that can accommodate the non-reducing disaccharides is key for their strong impact on lateral membrane organization. These exclusive interactions between the non-reducing sugars and the membranes may rationalize why organisms such as yeasts, tardigrades, nematodes, bacteria and plants accumulate sucrose and trehalose, offering cell protection under anhydrobiotic conditions. The proposed mechanism might prove to be a more generic way by which surface bound agents could affect membranes.