Computational simulations of structural role of the active-site W374C mutation of acetyl-coenzyme-A carboxylase: multi-drug resistance mechanism.
Herbicides targeting grass plastidic acetyl-CoA carboxylase (ACCase, EC 6.4.1.2) are selectively effective against graminicides. The intensive worldwide use of this herbicide family has selected for resistance genes in a number of grass weed species. Recently, the active-site W374C mutation was found to confer multi-drug resistance toward haloxyfop (HF), fenoxaprop (FR), Diclofop (DF), and clodinafop (CF) in A. myosuroides. In order to uncover the resistance mechanism due to W374C mutation, the binding of above-mentioned four herbicides to both wild-type and the mutant-type ACCase was investigated in the current work by molecular docking and molecular dynamics (MD) simulations. The binding free energies were calculated by molecular mechanics-Poisson-Boltzmann surface area (MM/PBSA) method. The calculated binding free energy values for four herbicides were qualitatively consistent with the experimental order of IC(50) values. All the computational model and energetic results indicated that the W374C mutation has great effects on the conformational change of the binding pocket and the ligand-protein interactions. The most significant conformational change was found to be associated with the aromatic amino acid residues, such as Phe377, Tyr161' and Trp346. As a result, the π-π interaction between the ligand and the residue of Phe377 and Tyr161', which make important contributions to the binding affinity, was decreased after mutation and the binding affinity for the inhibitors to the mutant-type ACCase was less than that to the wild-type enzyme, which accounts for the molecular basis of herbicidal resistance. The structural role and mechanistic insights obtained from computational simulations will provide a new starting point for the rational design of novel inhibitors to overcome drug resistance associated with W374C mutation.
Zhu
Xiao-Lei
XL
Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079, People's Republic of China.
Yang
Wen-Chao
WC
Yu
Ning-Xi
NX
Yang
Sheng-Gang
SG
Yang
Guang-Fu
GF
D000103:Acetyl-CoA Carboxylase / Q000737:chemistry* / Q000235:genetics; D019943:Amino Acid Substitution; D020134:Catalytic Domain; D003198:Computer Simulation; D018432:Drug Resistance, Multiple / Q000235:genetics*; D053209:Herbicide Resistance / Q000235:genetics*; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D006109:Poaceae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
D010940:Plant Proteins; D000103:Acetyl-CoA Carboxylase