Changes in Lipids Composition and Fluidity of Yeast Plasma Membrane as Response to Cold

Abstract

In order to function properly, plasma membranes have to preserve a suitable dynamic state of the bilayer even in changing environments, which alters their fluidity. This is achieved by active restructuring of membrane lipids composition. Perturbations in membrane structure determined by environment may result in significant disruption of its physiological function. Accordingly, its composition is modified as response to environmental changes. Because the fluid state of plasma membrane is mandatory for proper functioning, organisms exposed to changes in the environmental conditions alter their membrane lipid composition, to maintain membrane lipids in a lamellar liquid crystalline phase, and avoid the formation of a lamellar gel phase. One of the main adaptative mechanisms to overcome the negative effect of cold is the ability to finely adjust phospholipid composition and physical properties of their plasma membranes. The minimum growth temperature of a given organism is reached when the degree of fluidity of its plasma membrane becomes too low for allowing the trans-membrane-nutrient transport. Yeasts have long served as an attractive model of a eukaryotic system for studying the regulation of lipid biosynthesis and thermal adaptation of the plasma membrane: the ability of psychrophilic, psychrotolerant and mesophilic yeasts to change the composition of phospholipids may suggest that the extent of such changes may be an important controlling factor, which determines the yeast growth temperature limits and limits for their distribution in the environment. In this chapter, some essential aspects of the changes in lipids composition and fluidity of yeast plasma membrane as response to cold are reported.