Nature Chem. Biol. doi:10.1038/nchembio.145 (2009)

Bacteria use two biosynthetic pathways to create iron-scavenging molecules, called siderophores, that are essential to their proliferation. Most siderophore research has focused on one of these — the nonribosomal peptide synthetase (NRPS)-dependent pathway — whereas the other, the NRPS-independent siderophore (NIS) pathway, has been largely ignored.

James Naismith of the University of St Andrews in Scotland and his colleagues are the first to solve a NIS enzyme's structure: that of AcsD, which occurs in the plant pathogen Pectobacterium chrysanthemi.

The structure reveals that AcsD catalyses reactions between ATP, citric acid and an amino acid, l-serine, making a probable precursor to the siderophore. The authors hope their work will help in the design of inhibitors of siderophore-making enzymes from human pathogens.