3RMZ: Crystal Structure Of The W199f-MaugPRE-Methylamine Dehydrogenase Complex

Citation:
Abstract
The diheme enzyme MauG catalyzes the posttranslational modification of the precursor protein of methylamine dehydrogenase (preMADH) to complete biosynthesis of its protein-derived tryptophan tryptophylquinone (TTQ) cofactor. Catalysis proceeds through a high valent bis-Fe(IV) redox state and requires long-range electron transfer (ET), as the distance between the modified residues of preMADH and the nearest heme iron of MauG is 19.4 A. Trp199 of MauG resides at the MauG-preMADH interface, positioned midway between the residues that are modified and the nearest heme. W199F and W199K mutations did not affect the spectroscopic and redox properties of MauG, or its ability to stabilize the bis-Fe(IV) state. Crystal structures of complexes of W199F/K MauG with preMADH showed no significant perturbation of the MauG-preMADH structure or protein interface. However, neither MauG variant was able to synthesize TTQ from preMADH. In contrast, an ET reaction from diferrous MauG to quinone MADH, which does not require the bis-Fe(IV) intermediate, was minimally affected by the W199F/K mutations. W199F/K MauGs were able to oxidize quinol MADH to form TTQ, the putative final two-electron oxidation of the biosynthetic process, but with k(cat)/K(m) values approximately 10% that of wild-type MauG. The differential effects of the W199F/K mutations on these three different reactions are explained by a critical role for Trp199 in mediating multistep hopping from preMADH to bis-Fe(IV) MauG during the long-range ET that is required for TTQ biosynthesis.
PDB ID: 3RMZDownload
MMDB ID: 94042
PDB Deposition Date: 2011/4/21
Updated in MMDB: 2011/10
Experimental Method:
x-ray diffraction
Resolution: 1.72  Å
Source Organism:
Similar Structures:
Biological Unit for 3RMZ: hexameric; determined by author and by software (PISA)
Molecular Components in 3RMZ
Label Count Molecule
Proteins (6 molecules)
2
Methylamine Utilization Protein Maug
Molecule annotation
2
Methylamine Dehydrogenase Light Chain
Molecule annotation
2
Methylamine Dehydrogenase Heavy Chain
Molecule annotation
Chemicals (17 molecules)
1
2
2
4
3
4
4
2
5
1
6
1
7
1
8
1
9
1
* Click molecule labels to explore molecular sequence information.

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