Publications

• Mechanistic elucidation of the mycofactocin-biosynthetic radical S-adenosylmethionine protein, MftC.

  Khaliullin B., Ayikpoe R., Tuttle M., Latham J.A.

  Ribosomally synthesized and posttranslationally modified peptide (RiPP) pathways produce a diverse array of natural products. A subset of these pathways depends on radical <i>S</i>-adenosylmethionine proteins to modify the RiPP-produced peptide. Mycofactocin biosynthesis is one example of an <i>S< ... >> More

  Ribosomally synthesized and posttranslationally modified peptide (RiPP) pathways produce a diverse array of natural products. A subset of these pathways depends on radical <i>S</i>-adenosylmethionine proteins to modify the RiPP-produced peptide. Mycofactocin biosynthesis is one example of an <i>S</i>-adenosylmethionine protein-dependent RiPP pathway. Recently, it has been shown that MftC catalyzes the oxidative decarboxylation of the C-terminal tyrosine (Tyr-30) on the mycofactocin precursor peptide MftA; however, this product has not been verified by techniques other than MS. Herein, we provide a more detailed study of MftC catalysis and report a revised mechanism for MftC chemistry. We show that MftC catalyzes the formation of two isomeric products. Using a combination of MS, isotope labeling, and ¹H and ¹³C NMR techniques, we established that the major product, MftA*, is a tyramine-valine-cross-linked peptide formed by MftC through two <i>S</i>-adenosylmethionine-dependent turnovers. In addition, we show that the hydroxyl group on MftA Tyr-30 is required for MftC catalysis. Furthermore, we show that a substitution in the penultimate MftA Val-29 position causes the accumulation of an MftA** minor product. The ¹H NMR spectrum indicates that this minor product contains an αβ-unsaturated bond that likely arises from an aborted intermediate of MftA* synthesis. The finding that MftA* is the major product formed during MftC catalysis could have implications for the further elucidation of mycofactocin biosynthesis. << Less

  J. Biol. Chem. 292:13022-13033(2017) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Spectroscopic and Electrochemical Characterization of the Mycofactocin Biosynthetic Protein, MftC, Provides Insight into Its Redox Flipping Mechanism.

  Ayikpoe R., Ngendahimana T., Langton M., Bonitatibus S., Walker L.M., Eaton S.S., Eaton G.R., Pandelia M.E., Elliott S.J., Latham J.A.

  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 matu ... >> 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. << Less

  Biochemistry 58:940-950(2019) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.