Tryptophan tryptophylquinone biosynthesis: A radical approach to posttranslational modification

►MauG stabilizes a bis-Fe(IV) state with one heme as His-Fe(IV)=O and another as His-Fe(IV)-Tyr. ►MauG post-translationally modifies two tryptophan residues within a protein substrate. ►MauG mediates long range electron transfer from the protein substrate to the high valent hemes.