Figure 2

Structure of the Ss-SibL protein. (a) Ribbon representation of the dimeric Ss-SibL structure is viewed down its 2-fold axis. Subunits A and B are shown in green and blue, respectively. The SAH and 3-HK are shown as magenta and orange stick models. (b) and (c) The composite omit maps for the ligands in the binary and ternary complex crystals are contoured at the 1.5 σ level and drawn as grey mesh presentations. Each subunit of the bound Ss-SibL includes both SAH and 3-HK in the cleft. SAH is depicted as sticks with the carbon, oxygen, nitrogen and sulfur atoms in magenta, red, blue and yellow, whereas 3-HK is illustrated with the carbon, oxygen and nitrogen in orange, red and blue, respectively.