The secret life of RNA and lipids.

There is no life without RNA or lipids. But could there be life with only RNA and lipids? The discovery that RNA can catalyse reactions in addition to encoding information opened new directions for engineering life and the possibility of life emerging from an RNA World. But a key missing ingredient for RNA-based biochemical systems is a mechanism to organize RNAs and regulate their activity. Lipids, which are essential for life and one of the most ancient biomolecules, can spontaneously self-assemble to form membranous bilayers, theoretically providing a surface that can serve to concentrate, protect, and regulate RNAs. This review explores the interactions between RNA and lipids, including the chemical basis for their interactions, and the implications for synthetic biology, RNA World, and modern cell biology. We discuss observations that RNA can selectively bind to lipid membranes in a sequence-dependent manner, and entertain how these interactions might be employed to engineer RNA-based sensors and regulatory elements in synthetic systems. The emerging field of RNA-lipid interactions opens new possibilities for engineering orthogonal biochemistries for synthetic cells, innovations in RNA therapeutics, and discovering potentially new facets of cellular regulation.