Microbial Primer: Bacterial metallophores - their role for metal homeostasis and social interactions

Metals are essential trace elements for almost all organisms including bacteria. Yet, metals are toxic at high concentrations, requiring fine-tuned regulatory mechanisms to steer metal homeostasis inside cells. In this primer, we explain how bacterial metallophores - small secreted secondary metabolites - act as gatekeepers by carefully orchestrating the scavenging and uptake of essential metals whilst preventing intracellular toxicity and keeping toxic metals outside the cell. We further introduce metallophore diversity together with main synthesis, secretion and uptake mechanisms. Finally, we show how secreted metallophores shape ecological interactions between bacteria and with eukaryotic organisms and how fundamental research on metallophores opens promising avenues for therapeutic and biotechnological applications.