From ancient lipids to synthetic life

The function of the cell membrane as a barrier and a matrix for biochemical activity relies on the properties imparted by lipids. In eukaryotes, sterols are crucial for modulating the molecular order of membranes. Sterol ordering provides the basis for membrane lateral segregation and promotes a fluid, mechanically robust plasma membrane. How do organisms that lack sterols determine membrane order? Hopanoids are ancient bacterial membrane lipids that have been proposed as putative sterol surrogates. We now explore the role of hopanoids, their effect on membranes in Methylobacterium extorquens and reflect on the path to building functional synthetic membranes.