Phospholipid tail asymmetry allows cellular adaptation to anoxic environments

Membrane biophysical properties are critical to cell fitness and depend on unsaturated phospholipid acyl tails. These can only be produced in aerobic environments since eukaryotic desaturases require molecular oxygen. This raises the question of how cells maintain bilayer properties in anoxic environments. Here, we demonstrate the existence of an alternative pathway to regulate membrane fluidity that exploits phospholipid acyl-tail length asymmetry, replacing unsaturated species in the membrane lipidome. We show that the fission yeast, S. japonicus, which can grow in aerobic and anaerobic conditions, is capable of utilizing this strategy whereas its sister species, the well-known model organism S. pombe, cannot. The incorporation of asymmetric-tailed phospholipids might be a general adaptation to hypoxic environmental niches.