Data Sheet 8_AHAS structural changes caused by mutations result in differences in binding affinity and resistance to two herbicides in Cyperus difformis L..pdf

The AHAS with a site 376 mutation had higher GR₅₀ and I₅₀ values for bensulfuron-methyl than for pyrazosulfuron-ethyl, while the GR₅₀ and I₅₀ values of the AHAS with a site 574 mutation were the highest. The affinity of purified AHAS for the substrate revealed that all the mutations increased the affinity except for the Pro-197-Arg mutation. In addition, all the AHAS mutants had greater affinity for bensulfuron-methyl than for pyrazosulfuron-ethyl.

Molecular docking results revealed that AHAS formed hydrogen bonds, π–π bonds, and hydrophobic interactions with pyrazosulfuron-ethyl and bensulfuron-methyl. The total number and types of interactions with pyrazosulfuron-ethyl and benzosulfuron-methyl were obviously different between the mutant AHAS and wild-type AHAS. Therefore, in this study, different mutations in AHAS induced distinct structural alterations, which reduced the affinity of the enzyme for herbicides, consequently leading to the development of weed resistance.

The difference in affinity between the same mutant and the two herbicides led to a difference in resistance to the two herbicides. The results of this study are helpful for understanding the causes of weed resistance to herbicides at the structural level.</p>