The myxobacterial lipidome - Unusual structural features and specific changes during fruiting body development

Myxobacteria are Gram-negative soil bacteria with a complex life cycle. In response to starvation, they form multicellular aggregates named fruiting bodies, in which the cells differentiate into heatand desiccation-resistant myxospores. The biochemical changes during this process are mostly unknown. In this study, the lipidome of the model organism Myxococcus xanthus has been analyzed, in particular during the time course of fruiting body development. Besides deeper insights into fatty acid biosynthesis in these organisms, the analyses revealed an accumulation of unusual branched-chain ether lipids and the formation of triacylglycerol vesicles under developmental conditions. Furthermore, an activation of fatty acid -oxidation could be observed, and a family of stereospecific fatty acid -hydroxylases involved in this process has been identified. Evidence is presented that myxobacteria contain sphingolipids as another unusual structural feature in the lipidome. These data will help to shed more light into the lipid metabolism and the mechanisms governing the complex life cycle of myxobacteria. Enzymes of the bacterial lipid metabolism are interesting targets for the development of antibacterial agents, and the results gained from myxobacteria may give helpful hints to find homologous enzymes in pathogenic bacteria. Furthermore, the biosynthesis of several myxobacterial secondary metabolites relies on certain reactions from lipid metabolism. The data presented here will help to understand how primary and secondary metabolism work together to produce promising lead structures for pharmaceutical and agricultural use.