Comparative study of molecular mechanisms of sucrose & trehalose mediated protection and stabilization of Escherichia coli lipid membrane during desiccation

Abstract

Desiccation presents considerable challenges to the survival of various bacteria, disrupting cellular functions and damaging the structure of macromolecular assemblies. Dehydration can induce a phase transition in lipid membranes, shifting from a favorable fluid phase to an unfavorable gel-like structure. In response to this stress, various organisms evolve different types of protective mechanisms, among which an accumulation of disaccharides is particularly noteworthy. Despite large number studies are present in the literature, the detailed mechanism of how disaccharides mitigate the deleterious effect of desiccation on lipid membrane is still elusive. Our study examines how disaccharides, like sucrose and trehalose, protect lipid membranes derived from an Escherichia coli (E. coli) bacteria during desiccation, aiming to uncover the mechanisms behind membrane protection and its significance for bacterial survival. We have simulated the lipid membrane at six different hydration levels, ranging from fully hydrated (with a water-to-lipid ratio of 42) to severely dehydrated (with a ratio of 2), both in the presence and absence of sucrose. We monitor various structural and dynamical parameters of the lipid membrane with a reduction of the hydration level. We conduct a comparative analysis between sucrose and trehalose. Our findings indicate that dehydration negatively impacts the fluidity of the membrane, and both the disaccharides demonstrate nearly equal effectiveness in mitigating the adverse effects of extreme dehydration on the lipid membrane. Furthermore, we provide evidence supporting the validity of the vitrification and water replacement hypotheses in understanding the role of disaccharides in protecting lipid membranes.