Catalyzes the radical-mediated synthesis of 7,8-didemethyl-8-hydroxy-5-deazariboflavin (FO) from 5-amino-6-(D-ribitylamino)uracil and L-tyrosine. 5-amino-6-(D-ribitylamino)uracil + L-tyrosine + S-adenosyl-L-methionine = 2-iminoacetate + 5'-deoxyadenosine + 5-amino-5-(4-hydroxybenzyl)-6-(D-ribitylimino)-5,6-dihydrouracil + H(+) + L-methionine 5-amino-5-(4-hydroxybenzyl)-6-(D-ribitylimino)-5,6-dihydrouracil + S-adenosyl-L-methionine = 5'-deoxyadenosine + 7,8-didemethyl-8-hydroxy-5-deazariboflavin + H(+) + L-methionine + NH4(+) Binds 2 [4Fe-4S] clusters. The clusters are coordinated with 3 cysteines and an exchangeable S-adenosyl-L-methionine. Cofactor biosynthesis; coenzyme F0 biosynthesis. In the N-terminal section; belongs to the radical SAM superfamily. CofG family. In the C-terminal section; belongs to the radical SAM superfamily. CofH family.