METABOLIC ENGINEERING OF LIPIDS AT SEA: VIRAL INFECTION INDUCES THE LIPIDOME REMODELING OF THE BLOOM FORMING ALGAL CELL

Phytoplankton are marine photosynthetic microorganisms responsible for nearly half of the biosphere`s net photosynthesis, thus serving as the basis for the oceanic food chain. Viruses that infect phytoplankton turn over more than a quarter of the total photosynthetically fixed carbon. By that viruses serve as major ecological and evolutionary drivers of the oceanic food webs.

The ubiquitous marine microalga Emiliania huxleyi forms massive seasonal blooms in the North Atlantic Ocean that impact nutrient recycling and earth climate. Recent observations have indicated the involvement of cocclithoviruses (EhV) in the coordinated rapid demise of these blooms.

We applied LC/MS-based lipidomics approach to explore the modulation of lipids during interaction in this unique host-pathogen system. We show that lytic viral infection leads to massive remodeling of the cellular lipidome, predominantly inducing the biosynthesis of viral specific glycosphingolipids as well as the accumulation of highly saturated triacylglycerol lipids. In accord, up-regulation of genes encoding host de-novo fatty acids biosynthesis enzymes as well as the viral encoded de-novo sphingolipid biosynthesis enzymes was observed. These viral-induced lipids were found to accumulate in the infected algal cell as well as in the purified virion, thus pointing to the central role of these lipids for viral assembly.