On the Origins of Cyanuric Acid Hydrolase: Purification, Substrates, and Prevalence of AtzD from Pseudomonas sp. Strain ADP

Abstract

Cyanuric acid hydrolase (AtzD) from Pseudomonas sp. strain ADP was purified to homogeneity. Of 22 cyclic amides and triazine compounds tested, only cyanuric acid and N-methylisocyanuric acid were substrates. Other cyclic amidases were found not to hydrolyze cyanuric acid. Ten bacteria that use cyanuric acid as a sole nitrogen source for growth were found to contain either atzD or trzD, but not both genes.

Defining Sequence Space and Reaction Products within the Cyanuric Acid Hydrolase (AtzD)/Barbiturase Protein Family

“…2). Many of these genes have been associated with plasmids and transposons and could have spread to a variety of organisms via horizontal gene transfer (5,7,12,26,32). It is possible that some of these genes have spread more rapidly in recent times with the inadvertent selection pressure provided by the use of billions of pounds of anthropogenic s-triazine compounds.…”

“…Those masses with profiles that reflected increasing abundance and then subsequent decreasing abundance were noted. The associated masses from the experiment with unlabeled cyanuric acid were then compared to those from the experiment with [U- 13 C]cyanuric acid to generate a list of paired ions, where the difference between their masses could be attributed to the difference between 12 C and 13 C. For each of the paired ions selected, the average mass from each time point was averaged and the standard deviation determined (Microsoft Excel 2003) to obtain the mass and tolerance to use in the Elemental Composition software.…”

“…1B). Purified cyanuric acid hydrolases have been reported by several groups (12,20,36) to yield biuret and carbon dioxide, which represents an apparent cleavage of two carbon to nitrogen bonds within the six-membered ring of cyanuric acid (Fig. 1A).…”

“…The cyanuric acid hydrolases designated AtzD and TrzD were the first members of this family to be identified (12,20). The atzD gene in Pseudomonas sp.…”

“…TrzD is functionally identical to AtzD, catalyzing the cyanuric acid ring-opening reaction in the pathway. AtzD and TrzD were identified as being homologous, but they were not connected to any other proteins or protein families in those studies (12,20,26). Barbiturase was first purified to homogeneity from Rhodococcus erythropolis JCM3132 and shown to catalyze the hydrolytic opening of barbituric acid, an intermediate in the oxidative pyrimidine catabolic pathway (34,35).…”