Posttranslational Biosynthesis of the Protein-Derived Cofactor Tryptophan Tryptophylquinone

    Authors

    V. L. Davidson;C. M. Wilmot

    Comments

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    Abbreviated Journal Title

    Annu. Rev. Biochem..

    Keywords

    electron transfer; heme; enzyme; high-valent iron; hole hopping; QUINOHEMOPROTEIN AMINE DEHYDROGENASE; ELECTRON-TRANSFER COMPLEX; MAU; GENE-CLUSTER; METHYLAMINE DEHYDROGENASE; PARACOCCUS-DENITRIFICANS; CRYSTAL-STRUCTURE; QUINONE COFACTOR; LYSYL OXIDASE; DIFFERENT FORMS; REDOX COFACTOR; Biochemistry & Molecular Biology

    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 O-2. 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 similar to 40 angstrom 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.

    Journal Title

    Annual Review of Biochemistry, Vol 82

    Volume

    82

    Publication Date

    1-1-2013

    Document Type

    Review; Book Chapter

    Language

    English

    First Page

    531

    Last Page

    550

    WOS Identifier

    WOS:000321698100019

    ISSN

    0066-4154

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