6ZW9 image
Entry Detail
PDB ID:
6ZW9
Keywords:
Title:
[4Fe-4S]-dependent thiouracil desulfidase TudS (DUF523Vcz) soaked with 4-thiouracil (S-SAD data)
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2020-07-28
Release Date:
2020-09-30
Method Details:
Experimental Method:
Resolution:
1.76 Å
R-Value Free:
0.18
R-Value Work:
0.16
R-Value Observed:
0.16
Space Group:
C 1 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:DUF523 domain-containing protein
Chain IDs:A, B
Chain Length:166
Number of Molecules:2
Biological Source:uncultured bacterium
Primary Citation
Structural Evidence for a [4Fe-5S] Intermediate in the Non-Redox Desulfuration of Thiouracil.
Angew.Chem.Int.Ed.Engl. 60 424 431 (2021)
PMID: 32929873 DOI: 10.1002/anie.202011211

Abstact

We recently discovered a [Fe-S]-containing protein with in vivo thiouracil desulfidase activity, dubbed TudS. The crystal structure of TudS refined at 1.5 Å resolution is reported; it harbors a [4Fe-4S] cluster bound by three cysteines only. Incubation of TudS crystals with 4-thiouracil trapped the cluster with a hydrosulfide ligand bound to the fourth non-protein-bonded iron, as established by the sulfur anomalous signal. This indicates that a [4Fe-5S] state of the cluster is a catalytic intermediate in the desulfuration reaction. Structural data and site-directed mutagenesis indicate that a water molecule is located next to the hydrosulfide ligand and to two catalytically important residues, Ser101 and Glu45. This information, together with modeling studies allow us to propose a mechanism for the unprecedented non-redox enzymatic desulfuration of thiouracil, in which a [4Fe-4S] cluster binds and activates the sulfur atom of the substrate.

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