The intricate link between membrane lipid structure and composition and membrane structural properties in bacterial membranes

Abstract

It is now evident that the cell manipulates lipid composition to regulate different processes such as membrane protein insertion, assembly and function. Moreover, changes in membrane structure and properties, lipid homeostasis during growth and differentiation with associated changes in cell size and shape, and responses to external stress have been related to drug resistance across mammalian species and a range of microorganisms. While it is well known that the biomembrane is a fluid self-assembled nanostructure, the link between the lipid components and the structural properties of the lipid bilayer are not well understood. This perspective aims to address this topic with a view to a more detailed understanding of the factors that regulate bilayer structure and flexibility. We describe a selection of recent studies that address the dynamic nature of bacterial lipid diversity and membrane properties in response to stress conditions. This emerging area has important implications for a broad range of cellular processes and may open new avenues of drug design for selective cell targeting.

Fig. 1. Lipid compositions and structural organisations of bacterial membranes. (A) The main lipid classes and chemical structures of individual lipid species commonly found in bacterial membranes. (B) The chemical structures of fatty acyl chains identified in bacterial membranes. (C) The distinctive difference of lipid compositions and structures between G(−) such as E. coli and G(+) such as S. aureus. (D) The molecular shape of phospholipids in bacterial membranes and the molecular disorder-order transitions between the fluid liquid-disordered phase and gel-ordered phase. The assembly of lipids with different molecular shape can organise the lamellar phases into planar, positive and negative curved structures.

Fig. 2. The interrelated physical, structural and mechanical properties of bulk membranes and various parameters for each membrane property.

Fig. 3. The dynamic parameters for individual lipids and bulk membrane assembly, and the different extrinsic properties that can influence the dynamic behavior of membranes.