Why use many lipids when one is enough? Minimal membrane systems for deciphering the role of lipid complexity

There is no life without lipids. Lipids are essential for cell-environment interactions, cellular organization, and could have been instrumental in the emergence of life itself. Despite significant evolutionary divergence in the molecular composition of biological membranes, all known life forms converge on a single strategy for building responsive interfaces – the lipid membrane. Although a membrane can be assembled from only one type of lipid, biological membranes are built from a staggering diversity of lipid species. Why have cells evolved to make membranes that are so diverse? In this talk I will introduce two approaches to study how life employs the emergent properties of lipids to build responsive organizational interfaces between cells and their environment. First, we have developed the Minimal Cell (JCVI-Syn3B) and its pathogenic parent organism Mycoplasma mycoides as experimental platforms in which lipidome size can be manipulated. By tuning lipidome size from fewer than 10 to more than 100 lipid species we are beginning to decipher the role of lipidome complexity for cellular fitness in the context of a changing environment. Second, we are studying how two of the most ancient biomolecules on Earth, RNA and lipids, can selectively interact to form responsive systems. Our observations reveal a functional interaction between RNA and lipids, providing a simple answer to a fundamental question in the debate on the origin of life – how could primordial RNA molecules be regulated?