Figure A in S1 File. Crystals of AtzC grown in a PEG-based buffer (top) and a malonate-based buffer (bottom).

The bar is approximately 200 μM in length. Figure B in S1 File. Differential scanning fluorimetry of AtzC and its variants. Figure C in S1 File. pH dependency of AtzC-mediated ammelide deamination. Figure D in S1 File. Comparison of malonic acid and N-isopropylammelide. Overlay of malonate (red) and IPA (blue) highlighting structural similarities between the two. There is excellent spatial overlap of three key H-bond acceptor groups (A) and an H-bond donor (D) which were key in guiding the choice of the starting pose prior for the DFT calculations. Figure E in S1 File. Inhibition of AtzC by malonic acid. Figure F in S1 File. Docking malonic acid in AtzC active site. The DFT optimised structure (cyan) with the crystal structure (purple). Backbone atoms were restrained and all other atoms were allowed to move freely, as in the original calculations. Hydrogen atoms are not shown for clarity. Figure G in S1 File. Overlay of AtzC with bound malonate with CodA with bound inhibitor. CodA (3O7U; green) with bound inhibitor ((2R)-2-amino-2,5-dihydro-1,5,2-diazaphosphinin-6(1H)-one 2-oxide; ADDO) was superposed with AtzC (cyan) using the SSM algorithm as implemented in Coot. 329 residues superpose with a rmsd of 1.52 Angstrom and 15 gaps (out of a possible 402/422 residues for 3O7U/AtzC). The sequence identity between the two proteins is 28.3%. Malonate (mal) in bound the AtzC active site and ADDO bound in the CodA active site are labelled. Table A in S1 File. Oligonucleotides used in this study. (PDF)