Dihydroxy acid dehydratase(DHAD)is the third enzyme in the plant branched-chain amino acid biosynthetic pathway and the target for commercial herbicide development.We have previously reported the discovery of fungal n...Dihydroxy acid dehydratase(DHAD)is the third enzyme in the plant branched-chain amino acid biosynthetic pathway and the target for commercial herbicide development.We have previously reported the discovery of fungal natural product aspterric acid(AA)as a submicromolar inhibitor of DHAD through self-resistance gene directed genome mining.Here,we reveal the mechanism of AA inhibition on DHAD and the self-resistance mechanism of AstD,which is encoded by the self-resistance gene astD.As a competitive inhibitor,the hydroxycarboxylic acid group of AA mimics the binding of the natural substrate of DHAD,while the hydrophobic moiety of AA occupies the substrate entrance cavity.Compared to DHAD,AstD has a relatively narrow substrate channel to prevent AA from binding.Several mutants of DHAD were generated and assayed to validate the self-resistance mechanism and to confer Arabidopsis thaliana DHAD with AA resistance.These results will lead to the engineering of new type of herbicides targeting DHAD and provide direction for the ecological construction of herbicide-resistant crops.展开更多
基金supported by the National Key Research and Development Program of China 2018YFA0901900 to J.Z.and NIGMS R35GM118056 to Y.T.
文摘Dihydroxy acid dehydratase(DHAD)is the third enzyme in the plant branched-chain amino acid biosynthetic pathway and the target for commercial herbicide development.We have previously reported the discovery of fungal natural product aspterric acid(AA)as a submicromolar inhibitor of DHAD through self-resistance gene directed genome mining.Here,we reveal the mechanism of AA inhibition on DHAD and the self-resistance mechanism of AstD,which is encoded by the self-resistance gene astD.As a competitive inhibitor,the hydroxycarboxylic acid group of AA mimics the binding of the natural substrate of DHAD,while the hydrophobic moiety of AA occupies the substrate entrance cavity.Compared to DHAD,AstD has a relatively narrow substrate channel to prevent AA from binding.Several mutants of DHAD were generated and assayed to validate the self-resistance mechanism and to confer Arabidopsis thaliana DHAD with AA resistance.These results will lead to the engineering of new type of herbicides targeting DHAD and provide direction for the ecological construction of herbicide-resistant crops.
