Fig. 3. SMFS measurements of XMod-Doc-binding mode mutants.

a Arginine 191 and leucine 195 on Doc were mutated to alanine and glutamic acid, respectively, to disrupt their interaction with Coh in binding mode A. Arginine 140 and methionine 144 were mutated to alanine and glutamic acid, respectively, to disrupt their interaction with Coh in binding mode B. b Percentages of the two binding modes measured with WT XMod-Doc, BM^A-KO mutant, and BM^B-KO mutant at 400 nm/s pulling speed. The BM^A-KO mutant preferentially populates binding mode B while the BM^B-KO mutant preferentially populates binding mode A.