Iron-sulfur cluster-binding SPASM domain of mycofactocin radical SAM maturase MftC and similar proteins
This group is composed of Mycobacterium tuberculosis putative mycofactocin radical SAM maturase MftC and similar proteins. MftC is a radical S-adenosylmethionine (SAM) enzyme that may function to modify mycofactocin, a conserved polypeptide that might serve as an electron carrier. Radical SAM enzymes are characterized by a conserved CxxxCxxC motif, which coordinates the conserved iron-sulfur cluster that is involved in the reductive cleavage of SAM and generates a 5'-deoxyadenosyl radical, which in turn abstracts a hydrogen from the appropriately positioned carbon atom of the substrate. Radical SAM enzymes with a C-terminal SPASM domain contain at least one other iron-sulfur cluster. This group appears to contain one auxillary Fe-S cluster that is similar to the second auxillary 4Fe-4S cluster (AuxII) of Clostridium perfringens anaerobic sulfatase-maturating enzyme (anSME).