The structural biology of phenazine biosynthesis.

•Phenazines are bacterial and archeal virulence factors and respiratory pigments.•Their biosynthesis from chorismate involves five enzymes encoded in the phz-operon.•Structural biology was instrumental in finding the unique activities of PhzF and PhzB.•The tricyclic phenazine scaffold forms from two identical but unstable aminoketones.•Unrefined handling of reactive intermediates impacts pathway end-product ratios.