Fig. 6

Comparison of the MT domains of TioS and modeled BSLS. a A homology model for MT_BSLS generated with the Swiss-Model server using the MT-A structure from TioS(A_4aM₄A_4b) (pdb ID 5wmm). Sequence identity between the core of MT_4TioS and MT_BSLS is 32%. For context purposes, the A domain of TioS is shown in light gray. The generated model of MT_BSLS is shown in blue. The active site was identified by aligning the TioS structure (which contained S-adenosylhomocysteine, shown in green) with the MT_BSLS model. The N- and C-termini of MT_BSLS are shown in orange and magenta spheres, respectively. b The active site residues of the MT domain in TioS(A_4aM₄A_4b) (pdb ID 5wmm) that are proposed to interact with the valine side chain (magenta) of the enzyme-bound substrate (G525, W526, M540, W543, S632, Q635, D664, R666, and L738, shown in blue). The N-methylated product of the reaction (methyl group in green) was modeled into the active site [4]. c Residues in TioS(A_4aM₄A_4b) that interact with the substrate amino acid are conserved (yellow) in MT_BSLS