Delineating the rules for structural adaptation of membrane-associated proteins to evolutionary changes in membrane lipidome

Summary Membrane function is fundamental to life. Each species explores membrane lipid diversity within a genetically predefined range of possibilities. How membrane lipid composition in turn defines the functional space available for evolution of membrane-centered processes remains largely unknown. We address this fundamental question using related fission yeasts Schizosaccharomyces pombe and Schizosaccharomyces japonicus. We show that, unlike S. pombe that generates membranes where both glycerophospholipid acyl tails are predominantly 16–18 carbons long, S. japonicus synthesizes unusual “asymmetrical” glycerophospholipids where the tails differ in length by 6–8 carbons. This results in stiffer bilayers with distinct lipid packing properties. Retroengineered S. pombe synthesizing the S.-japonicus-type phospholipids exhibits unfolded protein response and downregulates secretion. Importantly, our protein sequence comparisons and domain swap experiments support the hypothesis that transmembrane helices co-evolve with membranes, suggesting that, on the evolutionary scale, changes in membrane lipid composition may necessitate extensive adaptation of the membrane-associated proteome.
Highlights • The two acyl tails in S. japonicus phospholipids tend to differ by 6–8 carbons • S. japonicus but not S. pombe FAS makes both medium and long-chain fatty acids • S. japonicus membranes are more ordered than membranes of its relative S. pombe • Changes in membrane lipids may drive co-evolution of transmembrane helices
Makarova et al. show that membranes of related fission yeasts S. pombe and S. japonicus are made of structurally distinct phospholipids because of the difference in fatty acid synthase activities. Bioinformatics and retro-engineering experiments reveal that evolutionary changes in lipid metabolism require adaptation of the membrane-associated proteome.