Researchers have decoded the genetic blueprint of Penicillium citrinum, a common citrus mold, to uncover how nature produces cyclopentachromone — a key building block for bioactive compounds with potential in cancer and inflammation treatments. The team identified a previously unknown enzyme, IscL, that creates a highly reactive sulfur-containing intermediate, offering new insights into fungal chemistry. This discovery could pave the way for novel pharmaceuticals by harnessing nature’s molecular tools.