Structures of coenzyme F(420) in Mycobacterium species.

The structure of coenzyme F(420) in Mycobacterium smegmatis was examined using proton NMR, amino acid analysis, and HPLC. The two major F(420) structures were shown to be composed of a chromophore identical to that of F(420) from Methanobacterium thermoautotrophicum, with a side chain of a ribityl residue, a lactyl residue and five or six glutamate groups (F(420)-5 and F(420)-6). Peptidase treatment studies suggested that L-glutamate groups are linked by gamma-glutamyl bonds in the side chain. HPLC analysis indicated that Mycobacterium tuberculosis, Mycobacterium bovis BCG, and Mycobacterium fortuitum have F(420)-5 and F(420)-6 as the predominant structures, whereas Mycobacterium avium contains F(420)-5, F(420)-6 and F(420)-7 in significant amounts. 7,8-Didemethyl 8-hydroxy 5-deazariboflavin (FO), an intermediate in F(420) biosynthesis, accounted for about 1-7% of the total deazaflavin in cells. Peptidase treatment of F(420) created F(420) derivatives that may be useful for the assay of enzymes involved in F(420) biosynthesis.