Structural and mechanistic insights into C-P bond hydrolysis by phosphonoacetate hydrolase.
Bacteria have evolved pathways to metabolize phosphonates as a nutrient source for phosphorus. In Sinorhizobium meliloti 1021, 2-aminoethylphosphonate is catabolized to phosphonoacetate, which is converted to acetate and inorganic phosphate by phosphonoacetate hydrolase (PhnA). Here we present detailed biochemical and structural characterization of PhnA that provides insights into the mechanism of C-P bond cleavage. The 1.35 Å resolution crystal structure reveals a catalytic core similar to those of alkaline phosphatases and nucleotide pyrophosphatases but with notable differences, such as a longer metal-metal distance. Detailed structure-guided analysis of active site residues and four additional cocrystal structures with phosphonoacetate substrate, acetate, phosphonoformate inhibitor, and a covalently bound transition state mimic provide insight into active site features that may facilitate cleavage of the C-P bond. These studies expand upon the array of reactions that can be catalyzed by enzymes of the alkaline phosphatase superfamily.
Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Vinayak
V
Agarwal
Svetlana A
SA
Borisova
William W
WW
Metcalf
Wilfred A
WA
van der Donk
Satish K
SK
Nair
D000085:Acetates / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000737:chemistry* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D008670:Metals / Q000378:metabolism; D008958:Models, Molecular; D010746:Phosphonoacetic Acid / Q000378:metabolism; D011487:Protein Conformation; D016962:Sinorhizobium meliloti / Q000201:enzymology* / Q000378:metabolism; D013379:Substrate Specificity
D000085:Acetates; D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D008670:Metals; D000469:Alkaline Phosphatase; C097254:phosphonoacetate hydrolase; D010746:Phosphonoacetic Acid