Methanococcus jannaschii coenzyme F420 analogues contain a terminal alpha-linked glutamate

Analyses of the F420s present in Methanococcus jannaschii have shown that these cells contain a series of -glutamyl-linked F420s capped with a single, terminal -linked L-glutamate. The predominant form of F420 was designated as -F420-3 and represented 86 % of the F420s in these cells. Analyses of Methanosarcina thermophila, Methanosarcina barkeri, Methanobacterium thermoautotrophicum, Archaeoglobus fulgidus, and Myco-bacterium smegmatis showed that they contained only -glutamyl-linked F420s. Coenzyme F420 (Fig. 1) is a name given to a group of redox active cofactors that are presently known to have only a limited distribution among the archaea and high GC gram-positive bacteria (3). Although playing a crucial role in methanoar-chaeal metabolism (4), coenzyme F420 has also been found in various eubacteria such as Streptomyces, Rhodococcus, Nocar-dioides, and Mycobacterium spp. and their relatives (3). The coenzyme, in fact, was first isolated in 1960 as a cofactor involved in the biosynthesis of chlortetracycline in Streptomyces aureofaciens (18). The coenzyme is presently known to be in