TY - JOUR
T1 - Cyanuric acid hydrolase reveal conformational flexibility and asymmetry important for catalysis
AU - Shi, Ke
AU - Cho, Seunghee
AU - Aukema, Kelly G.
AU - Lee, Thomas
AU - Bera, Asim K.
AU - Seffernick, Jennifer L.
AU - Wackett, Lawrence P.
AU - Aihara, Hideki
N1 - Publisher Copyright:
© 2019 Shi et al.
PY - 2019/6
Y1 - 2019/6
N2 - An ancient enzyme family responsible for the catabolism of the prebiotic chemical cyanuric acid (1,3,5-triazine-2,4,6-triol) was recently discovered and is undergoing proliferation in the modern world due to industrial synthesis and dissemination of 1,3,5-triazine compounds. Cyanuric acid has a highly stabilized ring system such that bacteria require a unique enzyme with a novel fold and subtle active site construction to open the ring. Each cyanuric acid hydrolase monomer consists of three isostructural domains that coordinate and activate the three-fold symmetric substrate cyanuric acid for ring opening. We have now solved a series of X-ray structures of an engineered, thermostable cyanuric acid ring-opening enzyme at 1.51 ~ 2.25 Å resolution, including various complexes with the substrate, a tight-binding inhibitor, or an analog of the reaction intermediate. These structures reveal asymmetric interactions between the enzyme and bound ligands, a metal ion binding coupled to conformational changes and substrate binding important for enzyme stability, and distinct roles of the isostructural domains of the enzyme. The multiple conformations of the enzyme observed across a series of structures and corroborating biochemical data suggest importance of the structural dynamics in facilitating the substrate entry and the ring-opening reaction, catalyzed by a conserved Ser-Lys dyad.
AB - An ancient enzyme family responsible for the catabolism of the prebiotic chemical cyanuric acid (1,3,5-triazine-2,4,6-triol) was recently discovered and is undergoing proliferation in the modern world due to industrial synthesis and dissemination of 1,3,5-triazine compounds. Cyanuric acid has a highly stabilized ring system such that bacteria require a unique enzyme with a novel fold and subtle active site construction to open the ring. Each cyanuric acid hydrolase monomer consists of three isostructural domains that coordinate and activate the three-fold symmetric substrate cyanuric acid for ring opening. We have now solved a series of X-ray structures of an engineered, thermostable cyanuric acid ring-opening enzyme at 1.51 ~ 2.25 Å resolution, including various complexes with the substrate, a tight-binding inhibitor, or an analog of the reaction intermediate. These structures reveal asymmetric interactions between the enzyme and bound ligands, a metal ion binding coupled to conformational changes and substrate binding important for enzyme stability, and distinct roles of the isostructural domains of the enzyme. The multiple conformations of the enzyme observed across a series of structures and corroborating biochemical data suggest importance of the structural dynamics in facilitating the substrate entry and the ring-opening reaction, catalyzed by a conserved Ser-Lys dyad.
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U2 - 10.1371/journal.pone.0216979
DO - 10.1371/journal.pone.0216979
M3 - Article
C2 - 31181074
AN - SCOPUS:85067102749
SN - 1932-6203
VL - 14
JO - PloS one
JF - PloS one
IS - 6
M1 - e0216979
ER -