Inhibition of Arabidopsis growth by the allelopathic compound azetidine-2-carboxylate is due to the low amino acid specificity of cytosolic prolyl-tRNA synthetase

Jiyeon Lee, Naveen Joshi, Rita Pasini, Renwick C.J. Dobson, Jane Allison, Thomas Leustek

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The toxicity of azetidine-2-carboxylic acid (A2C), a structural analogue of L-proline, results from its incorporation into proteins due to misrecognition by prolyl-tRNA synthetase (ProRS). The growth of Arabidopsis thaliana seedling roots is more sensitive to inhibition by A2C than is cotyledon growth. Arabidopsis contains two ProRS isozymes. AtProRS-Org (At5g52520) is localized in chloroplasts/mitochondria, and AtProRS-Cyt (At3g62120) is cytosolic. AtProRS-Cyt mRNA is more highly expressed in roots than in cotyledons. Arabidopsis ProRS isoforms were expressed as His-tagged recombinant proteins in Escherichia coli. Both enzymes were functionally active in ATP-PPi exchange and aminoacylation assays, and showed similar Km for L-proline. A major difference was observed in the substrate specificity of the two enzymes. AtProRS-Cyt showed nearly identical substrate specificity for L-proline and A2C, but for AtProRS-Org the specificity constant was 77.6 times higher for L-proline than A2C, suggesting that A2C-sensitivity may result from lower amino acid specificity of AtProRS-Cyt. Molecular modelling and simulation results indicate that this specificity difference between the AtProRS isoforms may result from altered modes of substrate binding. Similar kinetic results were obtained with the ProRSs from Zea mays, suggesting that the difference in substrate specificity is a conserved feature of ProRS isoforms from plants that do not accumulate A2C and are sensitive to A2C toxicity. The discovery of the mode of action of A2C toxicity could lead to development of biorational weed management strategies.

Original languageEnglish (US)
Pages (from-to)236-246
Number of pages11
JournalPlant Journal
Volume88
Issue number2
DOIs
StatePublished - Oct 1 2016

Fingerprint

Azetidinecarboxylic Acid
carboxylic acids
ligases
Arabidopsis
Amino Acids
amino acids
Growth
Proline
proline
substrate specificity
Substrate Specificity
Protein Isoforms
Cotyledon
toxicity
cotyledons
aminoacylation
Aminoacylation
prolyl T RNA synthetase
azetidine
Enzymes

All Science Journal Classification (ASJC) codes

  • Genetics
  • Plant Science
  • Cell Biology

Keywords

  • Arabidopsis thaliana
  • Zea mays
  • aminoacyl-tRNA synthetase
  • azetidine-2-carboxylic acid
  • prolyl-tRNA synthetase

Cite this

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title = "Inhibition of Arabidopsis growth by the allelopathic compound azetidine-2-carboxylate is due to the low amino acid specificity of cytosolic prolyl-tRNA synthetase",
abstract = "The toxicity of azetidine-2-carboxylic acid (A2C), a structural analogue of L-proline, results from its incorporation into proteins due to misrecognition by prolyl-tRNA synthetase (ProRS). The growth of Arabidopsis thaliana seedling roots is more sensitive to inhibition by A2C than is cotyledon growth. Arabidopsis contains two ProRS isozymes. AtProRS-Org (At5g52520) is localized in chloroplasts/mitochondria, and AtProRS-Cyt (At3g62120) is cytosolic. AtProRS-Cyt mRNA is more highly expressed in roots than in cotyledons. Arabidopsis ProRS isoforms were expressed as His-tagged recombinant proteins in Escherichia coli. Both enzymes were functionally active in ATP-PPi exchange and aminoacylation assays, and showed similar Km for L-proline. A major difference was observed in the substrate specificity of the two enzymes. AtProRS-Cyt showed nearly identical substrate specificity for L-proline and A2C, but for AtProRS-Org the specificity constant was 77.6 times higher for L-proline than A2C, suggesting that A2C-sensitivity may result from lower amino acid specificity of AtProRS-Cyt. Molecular modelling and simulation results indicate that this specificity difference between the AtProRS isoforms may result from altered modes of substrate binding. Similar kinetic results were obtained with the ProRSs from Zea mays, suggesting that the difference in substrate specificity is a conserved feature of ProRS isoforms from plants that do not accumulate A2C and are sensitive to A2C toxicity. The discovery of the mode of action of A2C toxicity could lead to development of biorational weed management strategies.",
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Inhibition of Arabidopsis growth by the allelopathic compound azetidine-2-carboxylate is due to the low amino acid specificity of cytosolic prolyl-tRNA synthetase. / Lee, Jiyeon; Joshi, Naveen; Pasini, Rita; Dobson, Renwick C.J.; Allison, Jane; Leustek, Thomas.

In: Plant Journal, Vol. 88, No. 2, 01.10.2016, p. 236-246.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Inhibition of Arabidopsis growth by the allelopathic compound azetidine-2-carboxylate is due to the low amino acid specificity of cytosolic prolyl-tRNA synthetase

AU - Lee, Jiyeon

AU - Joshi, Naveen

AU - Pasini, Rita

AU - Dobson, Renwick C.J.

AU - Allison, Jane

AU - Leustek, Thomas

PY - 2016/10/1

Y1 - 2016/10/1

N2 - The toxicity of azetidine-2-carboxylic acid (A2C), a structural analogue of L-proline, results from its incorporation into proteins due to misrecognition by prolyl-tRNA synthetase (ProRS). The growth of Arabidopsis thaliana seedling roots is more sensitive to inhibition by A2C than is cotyledon growth. Arabidopsis contains two ProRS isozymes. AtProRS-Org (At5g52520) is localized in chloroplasts/mitochondria, and AtProRS-Cyt (At3g62120) is cytosolic. AtProRS-Cyt mRNA is more highly expressed in roots than in cotyledons. Arabidopsis ProRS isoforms were expressed as His-tagged recombinant proteins in Escherichia coli. Both enzymes were functionally active in ATP-PPi exchange and aminoacylation assays, and showed similar Km for L-proline. A major difference was observed in the substrate specificity of the two enzymes. AtProRS-Cyt showed nearly identical substrate specificity for L-proline and A2C, but for AtProRS-Org the specificity constant was 77.6 times higher for L-proline than A2C, suggesting that A2C-sensitivity may result from lower amino acid specificity of AtProRS-Cyt. Molecular modelling and simulation results indicate that this specificity difference between the AtProRS isoforms may result from altered modes of substrate binding. Similar kinetic results were obtained with the ProRSs from Zea mays, suggesting that the difference in substrate specificity is a conserved feature of ProRS isoforms from plants that do not accumulate A2C and are sensitive to A2C toxicity. The discovery of the mode of action of A2C toxicity could lead to development of biorational weed management strategies.

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KW - Arabidopsis thaliana

KW - Zea mays

KW - aminoacyl-tRNA synthetase

KW - azetidine-2-carboxylic acid

KW - prolyl-tRNA synthetase

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