Coenzyme F420 is a family of
coenzymes involved in
redox reactions in a number of bacteria and archaea. It is derived from coenzyme FO (7,8-didemethyl-8-hydroxy-5-deazariboflavin) and differs by having a
oligoglutamyl tail attached via a 2-phospho-L-lactate bridge. F420 is so named because it is a
flavin derivative with an
absorption maximum at 420 nm.
F420 is structurally similar to
FMN, but catalytically it is similar to
NAD and
NADP: it has low
redox potential and always transfer a
hydride. As a result, it is not only a versatile cofactor in biochemical reactions, but also being eyed for potential as an industrial catalyst. Similar to FMN, it has two states: one reduced state, notated as F420-H2, and one oxidized state, written as just F420.[5] FO has largely similar redox properties, but cannot carry an electric charge and as a result probably slowly leaks out of the cellular membrane.[3]
A number of F420 molecules, differing by the length of the oligoglutamyl tail, are possible; F420-2, for example, refers to the version with two glutamyl units attached. Lengths from 4 to 9 are typical.[3]
Biosynthesis
Coenzyme F420 is synthesized via a multi-step pathway:
2-phospho-L-lactate transferase (FbiA) produces Coenzyme F420-0, the portion containing the head, the diphosphate bridge, and ending with a carboxylic acid group.
Coenzyme F420-1:gamma-L-glutamate ligase (other part of FbiB) puts a gamma-glutamate residue at the -COOH end, producing Coenzyme F420-2, the final compound (in its oxidized form). Also responsible for adding additional units.
A long list of other enzymes use F420 to oxidize (dehydrogenate) or F420-H2 to reduce substrates.[5]
Clinical relevance
Delamanid, a drug used to treat
multi-drug-resistant tuberculosis (MDRTB) in combination with other antituberculosis medications, is activated in the mycobacterium by
deazaflavin-dependent nitroreductase (Ddn), an enzyme which uses dihydro-F420 (reduced form). The activated form of the drug is highly reactive and attacks cell wall synthesis enzymes such as DprE2.
Pretomanid works in the same way. Clinical isolates resistant to these two drugs tend to have mutations in the biosynthetic pathway for F420.[9]
^Hagemeier CH, Shima S, Thauer RK, Bourenkov G, Bartunik HD, Ermler U (October 2003). "Coenzyme F420-dependent methylenetetrahydromethanopterin dehydrogenase (Mtd) from Methanopyrus kandleri: a methanogenic enzyme with an unusual quarternary structure". Journal of Molecular Biology. 332 (5): 1047–57.
doi:
10.1016/S0022-2836(03)00949-5.
PMID14499608.
^te Brömmelstroet BW, Geerts WJ, Keltjens JT, van der Drift C, Vogels GD (September 1991). "Purification and properties of 5,10-methylenetetrahydromethanopterin dehydrogenase and 5,10-methylenetetrahydromethanopterin reductase, two coenzyme F420-dependent enzymes, from Methanosarcina barkeri". Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology. 1079 (3): 293–302.
doi:
10.1016/0167-4838(91)90072-8.
PMID1911853.