title: Posttranslational biosynthesis of the protein-derived cofactor tryptophan tryptophylquinone.
abstract: Methylamine dehydrogenase (MADH) catalyzes the oxidative deamination of methylamine to formaldehyde and ammonia. Tryptophan tryptophylquinone (TTQ) is the protein-derived cofactor of MADH required for this catalytic activity. TTQ is biosynthesized through the posttranslational modification of two tryptophan residues within MADH, during which the indole rings of two tryptophan side chains are cross-linked and two oxygen atoms are inserted into one of the indole rings. MauG is a c-type diheme enzyme that catalyzes the final three reactions in TTQ formation. In total, this is a six-electron oxidation process requiring three cycles of MauG-dependent two-electron oxidation events using either H2O2 or O2. The MauG redox form responsible for the catalytic activity is an unprecedented bis-Fe(IV) species. The amino acids of MADH that are modified are ≈ 40 Å from the site where MauG binds oxygen, and the reaction proceeds by a hole hopping electron transfer mechanism. This review addresses these highly unusual aspects of the long-range catalytic reaction mediated by MauG.
authors.affiliation: Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32827, USA. victor.davidson@ucf.edu
authors.forename: Victor L
authors.initials: VL
authors.lastname: Davidson
authors.forename: Carrie M
authors.initials: CM
authors.lastname: Wilmot
mesh_terms: D002384:Catalysis; D004579:Electron Transport; D006418:Heme / Q000378:metabolism*; D045563:Indolequinones / Q000096:biosynthesis*; D010084:Oxidation-Reduction; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000378:metabolism*; D010231:Paracoccus denitrificans / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D045563:Indolequinones; C070569:tryptophan tryptophylquinone; D006418:Heme; D014364:Tryptophan; C021567:methylamine dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors