Figure 4. Structural and mutational analysis of the AlbS active site.

(A) Structural models of AlbS and Bnd4 displaying key active site residues (sticks) with a docked model of GGPP (gray ball and stick). The three Mg²⁺ ions (green spheres) from selinadiene synthase (PDB ID 4OKZ)³⁴ were overlaid to show their approximate positions.

(B) Relative cyclization activities of AlbS and mutants forming 1. Values are the mean of three independent experiments, which are shown as overlaid orange circles, with error bars representing standard deviations. The absence of a bar denotes no activity detected; NS denotes not soluble. Mutants marked with asterisks produced other products (see also Figs. 3 and S61).