2GAG: Heteroteterameric Sarcosine: Structure Of A Diflavin Metaloenzyme At 1.85 A Resolution

Citation:
Abstract
The crystal structure of heterotetrameric sarcosine oxidase (TSOX) from Pseudomonas maltophilia has been determined at 1.85 A resolution. TSOX contains three coenzymes (FAD, FMN and NAD+), four different subunits (alpha, 103 kDa; beta, 44 kDa; gamma, 21 kDa; delta, 11 kDa) and catalyzes the oxidation of sarcosine (N-methylglycine) to yield hydrogen peroxide, glycine and formaldehyde. In the presence of tetrahydrofolate, the oxidation of sarcosine is coupled to the formation of 5,10-methylenetetrahydrofolate. The NAD+ and putative folate binding sites are located in the alpha-subunit. The FAD binding site is in the beta-subunit. FMN is bound at the interface of the alpha and beta-subunits. The FAD and FMN rings are separated by a short segment of the beta-subunit with the closest atoms located 7.4 A apart. Sulfite, an inhibitor of oxygen reduction, is bound at the FMN site. 2-Furoate, a competitive inhibitor with respect to sarcosine, is bound at the FAD site. The sarcosine dehydrogenase and 5,10-methylenetetrahydrofolate synthase sites are 35 A apart but connected by a large internal cavity (approximately 10,000 A3). An unexpected zinc ion, coordinated by three cysteine and one histidine side-chains, is bound to the delta-subunit. The N-terminal half of the alpha subunit of TSOX (alphaA) is closely similar to the FAD-binding domain of glutathione reductase but with NAD+ replacing FAD. The C-terminal half of the alpha subunit of TSOX (alphaB) is similar to the C-terminal half of dimethylglycine oxidase and the T-protein of the glycine cleavage system, proteins that bind tetrahydrofolate. The beta-subunit of TSOX is very similar to monomeric sarcosine oxidase. The gamma-subunit is similar to the C-terminal sub-domain of alpha-TSOX. The delta-subunit shows little similarity with any PDB entry. The alphaA domain/beta-subunit sub-structure of TSOX closely resembles the alphabeta dimer of L-proline dehydrogenase, a heteroctameric protein (alphabeta)4 that shows highest overall similarity to TSOX.
PDB ID: 2GAGDownload
MMDB ID: 40906
PDB Deposition Date: 2006/3/8
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 1.85  Å
Source Organism:
Similar Structures:
Biological Unit for 2GAG: tetrameric; determined by author and by software (PISA)
Molecular Components in 2GAG
Label Count Molecule
Proteins (4 molecules)
1
Heterotetrameric Sarcosine Oxidase Alpha-subunit
Molecule annotation
1
Heterotetrameric Sarcosine Oxidase Beta-subunit
Molecule annotation
1
Heterotetrameric Sarcosine Oxidase Gamma-subunit
Molecule annotation
1
Heterotetrameric Sarcosine Oxidase Delta-subunit
Molecule annotation
Chemicals (8 molecules)
1
2
2
1
3
1
4
1
5
1
6
1
7
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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