7,8-didemethyl-8-hydroxy-5-deazariboflavin synthase (EC4.3.1.32, FO synthase) and 5-amino-6-(D-ribitylamino)uracil—L-tyrosine 4-hydroxyphenyl transferase (EC2.5.1.147) are two enzymes always complexed together to achieve synthesis of FO, a precursor to Coenzyme F420. Their systematic names are 5-amino-5-(4-hydroxybenzyl)-6-(D-ribitylimino)-5,6-dihydrouracil ammonia-lyase (7,8-didemethyl-8-hydroxy-5-deazariboflavin-forming) and 5-amino-6-(D-ribitylamino)uracil:L-tyrosine, 4-hydroxyphenyl transferase respectively.[1][2] The enzymes catalyse the following chemical reactions:
Enzyme 2.5.1.147 binds a 4Fe-4S cluster. The condensation reaction is initiated by the 5'-deoxyadenosyl radical. The complex was formerly named as a single entity under EC2.5.1.77.
All members of these enzymes belong to a single clade of the CofH (2.5.1.147) and CofG (4.3.1.32) families, sharing a TIM barrel structure. The two EC numbers represent discrete steps in this reaction. Some enzyme complexes have CofG and CofH (subunits 1 and 2) in different chains assembled into a heterodimer, while others like the bifunctional fbiC has the two domains on one single chain.
^Graham DE, Xu H, White RH (December 2003). "Identification of the 7,8-didemethyl-8-hydroxy-5-deazariboflavin synthase required for coenzyme F(420) biosynthesis". Archives of Microbiology. 180 (6): 455–64. doi:10.1007/s00203-003-0614-8. PMID14593448.
