Mechanistic insights into staphylopine-mediated metal acquisition

Metal acquisition is vital to pathogens for successful infection within hosts. Staphylopine (StP), a broad-spectrum metallophore biosynthesized by the major human pathogen, Staphylococcus aureus, plays a central role in transition-metal acquisition and bacterial virulence. The StP-like biosynthesis loci are present in various pathogens, and the proteins responsible for StP/metal transportation have been determined. However, the molecular mechanisms of how StP/metal complexes are recognized and transported remain unknown. We report multiple structures of the extracytoplasmic solute-binding protein CntA from the StP/metal transportation system in apo form and in complex with StP and three different metals. We elucidated a sophisticated metal-bound StP recognition mechanism and determined that StP/metal binding triggers a notable interdomain conformational change in CntA. Furthermore, CRISPR/Cas9-mediated single-base substitution mutations and biochemical analysis highlight the importance of StP/metal recognition for StP/metal acquisition. These discoveries provide critical insights into the study of novel metal-acquisition mechanisms in microbes.