Fig. 2.

Residues interacting with the sulfur atom. a Close-up view of the sulfur-binding cavity on ScoMcrA-SBD. The sulfur atom of PT-DNA is recognized by the pyrolidine ring of P165, the β-methylene groups of Y164 and H116, the β-methyl group of A168, and the γ-methylene group of R117 by hydrophobic interactions, as well as by the guanidinium group of R117 through electrostatic interaction. Electrostatic interactions are indicated as magenta dashed lines. b The view in a was rotated 90° towards left. c Schematic summary of the interactions between ScoMcrA-SBD and PT-DNA. d Mutations of key sulfur-recognizing or base-contacting residues disrupted or decreased the association between ScoMcrA-SBD and PT-DNA as analyzed by the EMSA assay. The original EMSA gels are shown in Supplementary Fig. 9