FeGP
FeGP is an iron-containing glycoprotein identified in several archaea and some bacteria. It is associated with the biosynthesis of cofactor F430, a nickel-containing tetrapyrrole used by methanogenic archaea to catalyze methane production. FeGP genes are typically located within operons that encode other components of the F430 biosynthetic pathway, suggesting a dedicated role in assembling or modifying the tetrapyrrole scaffold. Biochemical and genetic studies indicate that FeGP binds iron at a central site and contributes to the chemistry required to convert a tetrapyrrole precursor into FeGP or into a downstream intermediate that is further processed to F430. The exact catalytic mechanism is not fully resolved; proposed roles include substrate activation, metal-assisted transformations, or stabilization of reactive intermediates during cofactor assembly. Structural analyses in some members reveal a conserved core fold with residues coordinated to the metal, although the precise active site architecture can vary among organisms.
Distribution and significance: FeGP is predominantly found in methane-producing archaea and, less commonly, in affiliated bacteria