Secondary structure prediction of acetolactate synthase protein in sulfonylurea herbicide resistant Limnophila sessiliflora

Here, we cloned and sequenced fragments encoding ALS genes from biotypes of Limnophila sessiliflora susceptible and resistant to SU-herbicide. Comparisons of deduced amino acid sequences and secondary protein structures were implemented. The results showed that Pro was substituted with Gln and a G-X-X-P motif was abolished in Domain A of resistant ALS, and the secondary protein structure was converted from extended strands to an a-helix around Domain A by the Pro mutation. We suggest that resistance to SU-herbicides is caused by the mutation of ALS and conformational change of its secondary structure.