Dataset Information

Engineering Herbicide-Tolerance Rice Expressing an Acetohydroxyacid Synthase with a Single Amino Acid Deletion.

ABSTRACT: The acetohydroxyacid synthase (AHAS) is an essential enzyme involved in branched amino acids. Several herbicides wither weeds via inhibiting AHAS activity, and the AHAS mutants show tolerance to these herbicides. However, most AHAS mutations are residue substitutions but not residue deletion. Here, residue deletion was used to engineering the AHAS gene and herbicide-tolerant rice. Molecular docking analysis predicted that the W548 of the AHAS was a residue deletion to generate herbicide tolerance. The AHAS-?W548 protein was generated in vitro to remove the W548 residue. Interestingly, the deletion led to the tetramer dissociation of the AHAS, while this dissociation did not reduce the activity of the AHAS. Moreover, the W548 deletion contributed to multi-family herbicides tolerance. Specially, it conferred more tolerance to sulfometuron-methyl and bispyribac-sodium than the W548L substitution. Further analysis revealed that AHAS-?W548 had the best performance on the sulfometuron-methyl tolerance compared to the wild-type control. Over-expression of the AHAS-?W548 gene into rice led to the tolerance of multiple herbicides in the transgenic line. The T-DNA insertion and the herbicide treatment did not affect the agronomic traits and yields, while more branched-chain amino acids were detected in transgenic rice seeds. Residue deletion of W548 in the AHAS could be a useful strategy for engineering herbicide tolerant rice. The increase of branched-chain amino acids might improve the umami tastes of the rice.

SUBMITTER: Fang J

PROVIDER: S-EPMC7072996 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Engineering Herbicide-Tolerance Rice Expressing an Acetohydroxyacid Synthase with a Single Amino Acid Deletion.

Fang Jun J Wan Changzhao C Wang Wei W Ma Liuyin L Wang Xinqi X Cheng Can C Zhou Jihua J Qiao Yongjin Y Wang Xiao X

International journal of molecular sciences 20200213 4

The acetohydroxyacid synthase (AHAS) is an essential enzyme involved in branched amino acids. Several herbicides wither weeds via inhibiting AHAS activity, and the <i>AHAS</i> mutants show tolerance to these herbicides. However, most AHAS mutations are residue substitutions but not residue deletion. Here, residue deletion was used to engineering the <i>AHAS</i> gene and herbicide-tolerant rice. Molecular docking analysis predicted that the W548 of the AHAS was a residue deletion to generate herb ...[more]

PMID: 32070060

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Project description:The enzyme AHAS (acetohydroxy acid synthase), which is involved in the biosynthesis of valine, leucine and isoleucine, is the target of several classes of herbicides. A model of tobacco AHAS was generated based on the X-ray structure of yeast AHAS. Well conserved residues at the herbicide-binding site were identified, and the roles of three of these residues (Phe-205, Val-570 and Phe-577) were determined by site-directed mutagenesis. The Phe-205 mutants F205A, F205H, F205W and F205Y showed markedly decreased levels of catalytic efficiency, and cross-resistance to two or three classes of herbicides, i.e. Londax (a sulphonylurea herbicide), Cadre (an imidazolinone herbicide) and TP (a triazolopyrimidine derivative). None of the mutations caused significant changes in the secondary or tertiary structure of the enzyme. Four mutants of Phe-577, i.e. F577D, F577E, F577K and F577R, showed unaltered V(max) values, but substantially decreased catalytic efficiency. However, these mutants were highly resistant to two or three of the tested herbicides. The three mutants F577D, F577E and F577R had a similar secondary structure to that of wild-type AHAS. Conservative mutations of Phe-577, i.e. F577W and F577Y, did not affect the kinetic properties of the enzyme or its inhibition by herbicides. The mutation Val-570 to Asn abolished the binding affinity of the enzyme for FAD as well as its activity, and also caused a change in the tertiary structure of AHAS. However, the mutant V570Q was active, but resistant to two classes of herbicides, i.e. Londax and TP. The conservative mutant V570I was substantially reduced in catalytic efficiency and moderately resistant to the three herbicides. The results of this study suggest that residues Phe-205, Val-570 and Phe-577 in tobacco AHAS are located at or near the binding site that is common for the three classes of herbicides. In addition, Phe-205 and Val-570 are probably located at the herbicide-binding site that may overlap partially with the active site. Selected mutants of Phe-577 are expected to be utilized to construct herbicide-resistant transgenic plants.

Dataset Information

Engineering Herbicide-Tolerance Rice Expressing an Acetohydroxyacid Synthase with a Single Amino Acid Deletion.

Publications

Engineering Herbicide-Tolerance Rice Expressing an Acetohydroxyacid Synthase with a Single Amino Acid Deletion.

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