5t13

From Proteopedia

Structure of the Cyanuric Acid Hydrolase TrzD Reveals Product Exit Channel

Structural highlights

5t13 is a 1 chain structure with sequence from Enterobacter cloacae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.19Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

CAH_ENTCL Responsible for the hydrolysis of cyanuric acid, an intermediate formed during catabolism of s-triazine based compounds in herbicides such as atrazine and polymers such as melamine. Catalyzes the hydrolytic opening of the s-triazine ring of cyanuric acid (2,4,6-trihydroxy-s-triazine) to yield carbon dioxide and carboxybiuret, which spontaneously decarboxylates to biuret.[HAMAP-Rule:MF_01989]

Publication Abstract from PubMed

Cyanuric acid hydrolases are of industrial importance because of their use in aquatic recreational facilities to remove cyanuric acid, a stabilizer for the chlorine. Degradation of excess cyanuric acid is necessary to maintain chlorine disinfection in the waters. Cyanuric acid hydrolase opens the cyanuric acid ring hydrolytically and subsequent decarboxylation produces carbon dioxide and biuret. In the present study, we report the X-ray structure of TrzD, a cyanuric acid hydrolase from Acidovorax citrulli. The crystal structure at 2.19 A resolution shows a large displacement of the catalytic lysine (Lys163) in domain 2 away from the active site core, whereas the two other active site lysines from the two other domains are not able to move. The lysine displacement is proposed here to open up a channel for product release. Consistent with that, the structure also showed two molecules of the co-product, carbon dioxide, one in the active site and another trapped in the proposed exit channel. Previous data indicated that the domain 2 lysine residue plays a role in activating an adjacent serine residue carrying out nucleophilic attack, opening the cyanuric acid ring, and the mobile lysine guides products through the exit channel.

Structure of the Cyanuric Acid Hydrolase TrzD Reveals Product Exit Channel.,Bera AK, Aukema KG, Elias M, Wackett LP Sci Rep. 2017 Mar 27;7:45277. doi: 10.1038/srep45277. PMID:28345631^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Bera AK, Aukema KG, Elias M, Wackett LP. Structure of the Cyanuric Acid Hydrolase TrzD Reveals Product Exit Channel. Sci Rep. 2017 Mar 27;7:45277. doi: 10.1038/srep45277. PMID:28345631 doi:http://dx.doi.org/10.1038/srep45277