The Evolutionary Journey of the Sterol Synthesis Pathways in EukaryotesEvolution of sterol synthesis in eukaryotes

Abstract Sterols play key roles in eukaryotic cell membrane stability and dynamics, as signaling molecules, and as precursors in sterol-based metabolic pathways, including the production of steroid hormones. The sterol biosynthetic pathway, based on a common set of core reactions, has been subject to intense diversification in each major eukaryotic clade. As a result, these organisms display a bewildering panoply of sterol-derived compounds that correlate with their multiple lifestyles and adaptations. In this work, we provide new insights on sterol synthesis evolution and diversification in extant eukaryotes, with a special focus on algae and plants. In particular, we provide detailed information on the sterol synthesis pathway in bryophytes. A comprehensive phylogenetic analysis of bryophyte sterol biosynthetic enzymes suggests that duplications and divergence of the final enzymes of the canonical sterol pathway are taking place in this group.