Structures of coenzyme F420 in Mycobacterium species

The structure of coenzyme F420 in Mycobacterium smegmatis was examined using proton NMR, amino acid analysis, and HPLC. The two major F420 structures were shown to be composed of a chromophore identical to that of F420 from Methanobacterium thermoautotrophicum, with a side chain of a ribityl residue, a lactyl residue and five or six glutamate groups (F420–5 and F420–6). Peptidase treatment studies suggested that L-glutamate groups are linked by γ-glutamyl bonds in the side chain. HPLC analysis indicated that Mycobacterium tuberculosis, Mycobacterium bovis BCG, and Mycobacterium fortuitum have F420–5 and F420–6 as the predominant structures, whereas Mycobacterium avium contains F420–5, F420–6 and F420–7 in significant amounts. 7,8-Didemethyl 8-hydroxy 5-deazariboflavin (FO), an intermediate in F420 biosynthesis, accounted for about 1–7% of the total deazaflavin in cells. Peptidase treatment of F420 created F420 derivatives that may be useful for the assay of enzymes involved in F420 biosynthesis.