5BKE

Molecular basis for enantioselective herbicide degradation imparted by aryloxyalkanoate dioxygenases in transgenic plants.

(2019) Proc Natl Acad Sci U S A 116: 13299-13304

• PubMed: 31209034 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1073/pnas.1900711116
• Primary Citation of Related Structures:  
  5BK9, 5BKB, 5BKC, 5BKD, 5BKE


• PubMed Abstract: 
  

  The synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) is an active ingredient of thousands of commercial herbicides. Multiple species of bacteria degrade 2,4-D via a pathway initiated by the Fe(II) and α-ketoglutarate (Fe/αKG)-dependent aryloxyalkanoate dioxygenases (AADs). Recently, genes encoding 2 AADs have been deployed commercially in herbicide-tolerant crops. Some AADs can also inactivate chiral phenoxypropionate and aryloxyphenoxypropionate (AOPP) herbicides, albeit with varying substrate enantioselectivities. Certain AAD enzymes, such as AAD-1, have expanded utility in weed control systems by enabling the use of diverse modes of action with a single trait. Here, we report 1) the use of a genomic context-based approach to identify 59 additional members of the AAD class, 2) the biochemical characterization of AAD-2 from Bradyrhizobium diazoefficiens USDA 110 as a catalyst to degrade ( S )-stereoisomers of chiral synthetic auxins and AOPP herbicides, 3) spectroscopic data that demonstrate the canonical ferryl complex in the AAD-1 reaction, and 4) crystal structures of representatives of the AAD class. Structures of AAD-1, an ( R )-enantiomer substrate-specific enzyme, in complexes with a phenoxypropionate synthetic auxin or with AOPP herbicides and of AAD-2, which has the opposite ( S )-enantiomeric substrate specificity, reveal the structural basis for stereoselectivity and provide insights into a common catalytic mechanism.

   View More

---

Organizational Affiliation: 

Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801.