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Updated: May 29, 2026

Direct Detection of the Acetate-forming Activity of the Enzyme Acetate Kinase
Published on: December 19, 2011
Investigating substrate specificity in arogenate versus prephenate dehydratases.
Emily J Clayton1,2, Megan Smith-Uffen3, Travis W Tribble3
1Department of Biology, University of Western Ontario, 1151 Richmond Street North, London, ON, N6A 5B7, Canada. emily.clayton@concordia.ca.
Amino acid combinations in the regulatory ACT domain of Arabidopsis thaliana arogenate dehydratases (AtADTs) determine both arogenate dehydratase (ADT) and prephenate dehydratase (PDT) activity. This finding clarifies substrate specificity in phenylalanine biosynthesis.
Area of Science:
- Biochemistry
- Plant Molecular Biology
Background:
- Phenylalanine biosynthesis occurs via distinct pathways in microorganisms (prephenate pathway) and plants (arogenate pathway).
- Arabidopsis thaliana possesses six arogenate dehydratase (ADT) enzymes, with some exhibiting dual ADT and prephenate dehydratase (PDT) activity.
- High sequence similarity among AtADTs complicates in silico prediction of substrate specificity.
Purpose of the Study:
- To identify specific amino acids conferring prephenate dehydratase (PDT) activity in Arabidopsis thaliana arogenate dehydratases (AtADTs).
- To elucidate the role of these amino acids in determining both arogenate dehydratase (ADT) and PDT activity.
Main Methods:
- Domain swapping and targeted mutagenesis were employed to alter AtADT sequences.
- Yeast complementation assays (pha2 yeast) were used to assess PDT activity.
- A novel in vivo assay was developed to evaluate ADT activity.
Main Results:
- Specific amino acid residues within the regulatory ACT domain were identified as critical for enzyme function.
- These amino acid changes influenced both ADT and PDT activities of the AtADTs.
- The study successfully linked specific amino acid combinations to substrate specificity.
Conclusions:
- A combination of amino acids within the regulatory ACT domain is essential for both ADT and PDT activity in AtADTs.
- This highlights the structural basis for substrate specificity in phenylalanine biosynthesis enzymes.
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