Structures of coenzyme F₄₂₀ in Mycobacterium species

Abstract.

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.