title: X-ray structure of the amidase domain of AtzF, the allophanate hydrolase from the cyanuric acid-mineralizing multienzyme complex.
abstract: The activity of the allophanate hydrolase from Pseudomonas sp. strain ADP, AtzF, provides the final hydrolytic step for the mineralization of s-triazines, such as atrazine and cyanuric acid. Indeed, the action of AtzF provides metabolic access to two of the three nitrogens in each triazine ring. The X-ray structure of the N-terminal amidase domain of AtzF reveals that it is highly homologous to allophanate hydrolases involved in a different catabolic process in other organisms (i.e., the mineralization of urea). The smaller C-terminal domain does not appear to have a physiologically relevant catalytic function, as reported for the allophanate hydrolase of Kluyveromyces lactis, when purified enzyme was tested in vitro. However, the C-terminal domain does have a function in coordinating the quaternary structure of AtzF. Interestingly, we also show that AtzF forms a large, ca. 660-kDa, multienzyme complex with AtzD and AtzE that is capable of mineralizing cyanuric acid. The function of this complex may be to channel substrates from one active site to the next, effectively protecting unstable metabolites, such as allophanate, from solvent-mediated decarboxylation to a dead-end metabolic product.
authors.affiliation: CSIRO Land and Water Flagship, Black Mountain, Canberra, ACT, Australia Research School of Chemistry, Australian National University, Canberra, ACT, Ausralia.
authors.forename: Sahil
authors.initials: S
authors.lastname: Balotra
authors.affiliation: CSIRO Biomedical Manufacturing Program, Parkville, VIC, Australia.
authors.forename: Janet
authors.initials: J
authors.lastname: Newman
authors.affiliation: Australian Synchrotron, Clayton, VIC, Australia.
authors.forename: Nathan P
authors.initials: NP
authors.lastname: Cowieson
authors.affiliation: CSIRO Land and Water Flagship, Black Mountain, Canberra, ACT, Australia.
authors.forename: Nigel G
authors.initials: NG
authors.lastname: French
authors.affiliation: CSIRO Land and Water Flagship, Black Mountain, Canberra, ACT, Australia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Campbell
authors.affiliation: CSIRO Land and Water Flagship, Black Mountain, Canberra, ACT, Australia.
authors.forename: Lyndall J
authors.initials: LJ
authors.lastname: Briggs
authors.affiliation: CSIRO Land and Water Flagship, Black Mountain, Canberra, ACT, Australia.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Warden
authors.affiliation: Research School of Chemistry, Australian National University, Canberra, ACT, Ausralia.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Easton
authors.affiliation: CSIRO Biomedical Manufacturing Program, Parkville, VIC, Australia.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Peat
authors.affiliation: CSIRO Land and Water Flagship, Black Mountain, Canberra, ACT, Australia colin.scott@csiro.au.
authors.forename: Colin
authors.initials: C
authors.lastname: Scott
mesh_terms: D000492:Allophanate Hydrolase / Q000737:chemistry* / Q000378:metabolism*; D000581:Amidohydrolases / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D011549:Pseudomonas / Q000201:enzymology; D014227:Triazines / Q000378:metabolism*
chemical_list: D009097:Multienzyme Complexes; D014227:Triazines; D000581:Amidohydrolases; C019665:amidase; D000492:Allophanate Hydrolase; C004632:cyanuric acid