Research Article | Open Access

Volume 2024 |Article ID 0046 | https://doi.org/10.34133/bdr.0046

Structural Bases of Dihydroxy Acid Dehydratase Inhibition and Biodesign for Self-Resistance

Xin Zang,^1,9 Undramaa Bat-Erdene,^2,9 Weixue Huang,³ Zhongshou Wu,^4,5 Steve E. Jacobsen,^4,5,6,7 Yi Tang ,² Jiahai Zhou ^1,8

¹Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academyof Sciences, Shenzhen 518055, China
²Department of Chemical and Biomolecular Engineering, Universityof California, Los Angeles, CA, USA
³State Key Laboratory of Chemical Biology, Shanghai Institute ofOrganic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
⁴Department of MolecularCell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
⁵Howard HughesMedical Institute, University of California, Los Angeles, CA 90095, USA
⁶Eli and Edythe Broad Center ofRegenerative Medicine and Stem Cell Research, University of California, Los Angeles, CA 90095, USA
⁷Department of Biological Chemistry, University of California, Los Angeles, CA 90095, USA
⁸School ofFood Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
⁹These authors contributed equally to this work

Abstract

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.