Figure legend
Figure 1. The crystal structure of apo-GmCHS1. A: The overall structure of apo-GmCHS1 homodimer, with each monomer is colored in either cyan or green. Dotted circle indicates the active site of the monomer, and the catalytic residues are represented in stick models as will be shown in D. B: Surface representations of apo-GmCHS1 homodimer. Left: The view from same direction with panel A. Right: The view of 30° rotated around the y-axis. The arrow and dotted circle (orange) indicates the entrance of the putative CoA-binging tunnel.14 C: An interior cavity of apo-GmCHS1, which is predicted by the CASTp program, is shown in the surface representation. Black arrow indicates the entrance of the CoA-binding tunnel as described above, whereas dotted arrow (red) indicates another tunnel connecting to the active site. Dotted circle highlights the active site, as is shown in panel A. D: A close-up view of the active site of GmCHS1. The 2FoFc electron density maps contoured at 1σ are represented for the catalytic cysteine sulfinic acid (CSD164), His302 and Asn335. Distance (Å) between the sulfur atom of CSD164 and the Nε of His302 is labeled and shown as a dotted line.
Figure 2. The crystal structure of GmCHS1 complexed with naringenin. A: A close-up view of the active site of GmCHS1 with bound naringenin (NAR) and citrate ion (CIT). The 2FoFcelectron density maps contoured at 1σ are shown for naringenin, Phe215 and Phe264. B: Stereo view of the important residues, the naringenin and the citrate ion in the active site of GmCHS1. C: Superposition of the apo- and naringenin-bound structures of GmCHS1(green: the apo-structure, cyan: the complex structure). The active sites from both structures are shown without indicating the citrate ion in the complex structure. The 2FoFc electron density map for naringenin is shown as in panel A except indicating the stick model. Dotted double arrow indicates the possible movement of Phe264. See also Figure S2.