Diversity of Function in the Isocitrate Lyase Enzyme Superfamily: TheDianthus caryophyllusPetal Death Protein Cleaves α-Keto and α-Hydroxycarboxylic Acids
| Autor: | Osnat Herzberg, Xiaohua Feng, Ling Song, William R. Woodson, Debra Dunaway-Mariano, Brian M. Martin, Patrick S. Mariano, Alexander Kim, Ying Han, Zhibing Lu |
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| Rok vydání: | 2005 |
| Předmět: |
Models
Molecular Molecular Sequence Data Carboxylic Acids Cleavage (embryo) medicine.disease_cause Biochemistry Catalysis Substrate Specificity Phosphoenolpyruvate mutase Dianthus medicine Citrate synthase Amino Acid Sequence Enzyme kinetics Cloning Molecular Nuclear Magnetic Resonance Biomolecular Escherichia coli Plant Proteins chemistry.chemical_classification Sequence Homology Amino Acid biology Hydrolysis Isocitrate lyase Hydrogen-Ion Concentration biology.organism_classification Isocitrate Lyase Enzyme chemistry biology.protein |
| Zdroj: | Biochemistry. 44:16365-16376 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi051776l |
| Popis: | The work described in this paper was carried out to define the chemical function a new member of the isocitrate lyase enzyme family derived from the flowering plant Dianthus caryophyllus. This protein (Swiss-Prot entry Q05957) is synthesized in the senescent flower petals and is named the "petal death protein" or "PDP". On the basis of an analysis of the structural contexts of sequence markers common to the C-C bond lyases of the isocitrate lyase/phosphoenolpyruvate mutase superfamily, a substrate screen that employed a (2R)-malate core structure was designed. Accordingly, stereochemically defined C(2)- and C(3)-substituted malates were synthesized and tested as substrates for PDP-catalyzed cleavage of the C(2)-C(3) bond. The screen identified (2R)-ethyl, (3S)-methylmalate, and oxaloacetate [likely to bind as the hydrate, C(2)(OH)(2) gem-diol] as the most active substrates (for each, k(cat)/K(m) = 2 x 10(4) M(-)(1) s(-)(1)). In contrast to the stringent substrate specificities previously observed for the Escherichia coli isocitrate and 2-methylisocitrate lyases, the PDP tolerated hydrogen, methyl, and to a much lesser extent acetate substituents at the C(3) position (S configuration only) and hydoxyl, methyl, ethyl, propyl, and to a much lesser extent isobutyl substituents at C(2) (R configuration only). It is hypothesized that PDP functions in oxalate production in Ca(2+) sequestering and/or in carbon scavenging from alpha-hydroxycarboxylate catabolites during the biochemical transition accompanying petal senescence. |
| Databáze: | OpenAIRE |
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