Identification of Autoinducing Thiodepsipeptides from Staphylococci Enabled by Native Chemical Ligation

Staphylococci secrete autoinducing peptides (AIPs) as signalling molecules to regulate population-wide behaviour. AIPs from non-Staphylococcus aureus staphylococci have received attention as potential antivirulence agents to inhibit quorum sensing and virulence gene expression in the human pathogen Staphylococcus aureus. However, only a limited number of AIP structures from non-S. aureus staphylococci have been identified to date, as the minute amounts secreted in complex media render it difficult. Here, we report a method for the identification of AIPs by exploiting their thiolactone functionality for chemoselective trapping and enrichment of the compounds from the bacterial supernatant. Standard liquid chromatography mass spectrometry analysis, guided by genome sequencing data, then readily provides the AIP identities. Using this approach, we confirm the identity of five known AIPs and identify the AIPs of eleven non-S. aureus species, and we expect that the method should be extendable to AIP-expressing Gram-positive bacteria beyond the Staphylococcus genus.