Mycofactocin is a putative redox cofactor and is classified as a ribosomally synthesized and post-translationally modified peptide (RiPP). Some RiPP natural products， including mycofactocin， rely on a radical S-adenosylmethionine (RS， SAM) protein to modify the precursor peptide. Mycofactocin maturase， MftC， is a unique RS protein that catalyzes the oxidative decarboxylation and C-C bond formation on the precursor peptide MftA. However， the number， chemical nature， and catalytic roles for the MftC [Fe-S] clusters remain unknown. Here， we report that MftC binds a RS [4Fe-4S] cluster and two auxiliary [4Fe-4S] clusters that are required for MftA modification. Furthermore， electron paramagnetic... More
Mycofactocin is a putative redox cofactor and is classified as a ribosomally synthesized and post-translationally modified peptide (RiPP). Some RiPP natural products， including mycofactocin， rely on a radical S-adenosylmethionine (RS， SAM) protein to modify the precursor peptide. Mycofactocin maturase， MftC， is a unique RS protein that catalyzes the oxidative decarboxylation and C-C bond formation on the precursor peptide MftA. However， the number， chemical nature， and catalytic roles for the MftC [Fe-S] clusters remain unknown. Here， we report that MftC binds a RS [4Fe-4S] cluster and two auxiliary [4Fe-4S] clusters that are required for MftA modification. Furthermore， electron paramagnetic resonance spectra of MftC suggest that SAM and MftA affect the environments of the RS and Aux I cluster， whereas the Aux II cluster is unaffected by the substrates. Lastly， reduction potential assignments of individual [4Fe-4S] clusters by protein film voltammetry show that their potentials are within 100 mV of each other.
