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Non-specific activities of the major herbicide-resistance gene BAR.

  • Christ B Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA.
  • Hochstrasser R Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland.
  • Guyer L Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland.
  • Francisco R Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland.
  • Aubry S Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland.
  • Hörtensteiner S Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland. shorten@botinst.uzh.ch.
  • Weng JK Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA. wengj@wi.mit.edu.
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  • 2017-11-29
Published in:
  • Nature plants. - 2017
Acetyltransferases
Arabidopsis
Bacterial Proteins
Brassica napus
Crystallography, X-Ray
Genes, Bacterial
Herbicide Resistance
Metabolome
Models, Molecular
Organophosphorus Compounds
Plants, Genetically Modified
Soybeans
Streptomyces
Triticum
English Bialaphos resistance (BAR) and phosphinothricin acetyltransferase (PAT) genes, which convey resistance to the broad-spectrum herbicide phosphinothricin (also known as glufosinate) via N-acetylation, have been globally used in basic plant research and genetically engineered crops 1-4 . Although early in vitro enzyme assays showed that recombinant BAR and PAT exhibit substrate preference toward phosphinothricin over the 20 proteinogenic amino acids 1 , indirect effects of BAR-containing transgenes in planta, including modified amino acid levels, have been seen but without the identification of their direct causes 5,6 . Combining metabolomics, plant genetics and biochemical approaches, we show that transgenic BAR indeed converts two plant endogenous amino acids, aminoadipate and tryptophan, to their respective N-acetylated products in several plant species. We report the crystal structures of BAR, and further delineate structural basis for its substrate selectivity and catalytic mechanism. Through structure-guided protein engineering, we generated several BAR variants that display significantly reduced non-specific activities compared with its wild-type counterpart in vivo. The transgenic expression of enzymes can result in unintended off-target metabolism arising from enzyme promiscuity. Understanding such phenomena at the mechanistic level can facilitate the design of maximally insulated systems featuring heterologously expressed enzymes.
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  • English
Open access status
green
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https://sonar.ch/global/documents/95268
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