Systematic lipidomic mapping of Mycobacterium tuberculosis reveals that over half of detectable lipids remain uncharacterized, enabling the discovery of lysyldiacylglycerol as a conserved virulence lipid produced by the lysX gene in mycobacteria and the mprF gene in Staphylococcus aureus, where lysX disruption attenuates infection across evolutionarily diverse host models.

Unlike gene-first approaches to understanding bacterial pathogenesis, molecule-forward discovery can uncover unexpected chemical diversity. Here, new lipidomic analytical methods and quality metrics defined the large scope of unknown lipids in the world’s deadliest pathogen, Mycobacterium tuberculosis (Mtb). This map allowed rapid discovery of Mtb lysyldiacylglycerol linked to the biosynthetic gene lysX, which controls in vivo infection outcomes in moth larvae, mice, guinea pigs, and here, zebrafish. A broader search for orthologous lysyltransferase domains identified the Staphylococcus aureus virulence gene mprF, where the same lipoamino acid was shown to be a previously unknown biosynthetic product. Thus, lipidomic mapping showed that the cell envelope composition of well-studied bacterial pathogens remains substantially unsolved and offers a new way to generate lists of discoverable lipids to accelerate molecular discovery.