期刊
BIOCHEMISTRY
卷 50, 期 14, 页码 2931-2938出版社
AMER CHEMICAL SOC
DOI: 10.1021/bi200023n
关键词
-
资金
- NIH [GM-66569, GM-41574]
- Minnesota Partnership for Biotechnology and Medical Genomics Grant [SPAP-05-0013-P-FY06]
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 herne-bound diatomic oxygen intermediates in promoting cleavage of the O-O bond. Pro 107 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.
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