Abstract
MauG is a diheme enzyme responsible for the post-translational formation of the catalytic tryptophan tryptophylquinone (TTQ) cofactor in methylamine dehydrogenase (MADH). MauG can utilize hydrogen peroxide, or molecular oxygen and reducing equivalents, to complete this reaction via a catalytic bis-Fe(IV) intermediate. Crystal structures of diferrous, Fe(II)-CO, and Fe(II)-NO forms of MauG in complex with its preMADH substrate have been determined and compared to one another as well as to the structure of the resting diferric MauG-preMADH complex. CO and NO each bind exclusively to the 5-coordinate high-spin heme with no change in ligation of the 6-coordinate low-spin heme. These structures reveal likely roles for amino acid residues in the distal pocket of the high-spin heme in oxygen binding and activation. Glu113 is implicated in the protonation of heme-bound diatomic oxygen intermediates in promoting cleavage of the O-O bond. Pro107 is shown to change conformation on the binding of each ligand and may play a steric role in oxygen activation by positioning the distal oxygen near Glu113. Gln103 is in a position to provide a hydrogen bond to the Fe(IV)═O moiety that may account for the unusual stability of this species in MauG.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, Non-U.S. Gov't
-
Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
-
Amino Acid Sequence
-
Bacterial Proteins / chemistry
-
Bacterial Proteins / genetics
-
Bacterial Proteins / metabolism*
-
Binding Sites
-
Biocatalysis
-
Carbon Monoxide / chemistry*
-
Crystallography, X-Ray
-
Cytochrome-c Peroxidase / chemistry
-
Cytochrome-c Peroxidase / genetics
-
Cytochrome-c Peroxidase / metabolism*
-
Ferrous Compounds / chemistry
-
Glutamic Acid / chemistry
-
Glutamic Acid / genetics
-
Glutamic Acid / metabolism
-
Heme / chemistry
-
Heme / metabolism
-
Hemeproteins / chemistry
-
Hemeproteins / genetics
-
Hemeproteins / metabolism*
-
Indolequinones / chemistry
-
Indolequinones / metabolism
-
Models, Chemical
-
Models, Molecular
-
Molecular Sequence Data
-
Molecular Structure
-
Nitric Oxide / chemistry*
-
Oxidoreductases / metabolism
-
Oxidoreductases Acting on CH-NH Group Donors / chemistry
-
Oxidoreductases Acting on CH-NH Group Donors / genetics
-
Oxidoreductases Acting on CH-NH Group Donors / metabolism*
-
Oxygen / chemistry
-
Oxygen / metabolism
-
Paracoccus denitrificans / genetics
-
Paracoccus denitrificans / metabolism
-
Protein Binding
-
Protein Structure, Tertiary
-
Sequence Homology, Amino Acid
-
Spectrophotometry
-
Substrate Specificity
-
Tryptophan / analogs & derivatives
-
Tryptophan / chemistry
-
Tryptophan / metabolism
Substances
-
Bacterial Proteins
-
Ferrous Compounds
-
Hemeproteins
-
Indolequinones
-
tryptophan tryptophylquinone
-
Nitric Oxide
-
Glutamic Acid
-
Heme
-
Carbon Monoxide
-
Tryptophan
-
Oxidoreductases
-
Cytochrome-c Peroxidase
-
methylamine dehydrogenase
-
Oxidoreductases Acting on CH-NH Group Donors
-
diheme cytochrome c
-
Oxygen
Associated data
-
PDB/3PXS
-
PDB/3PXT
-
PDB/3PXW