Metabolic pathway promiscuity in the archaeon Sulfolobus solfataricus revealed by studies on glucose dehydrogenase and 2-keto-3-deoxygluconate aldolase
| Autor: | Steven D. Bull, David W. Hough, Michael J. Danson, Narinder I. Heyer, Henry J. Lamble |
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| Rok vydání: | 2003 |
| Předmět: |
Time Factors
ved/biology.organism_classification_rank.species Glucose Dehydrogenases Molecular Sequence Data Glyceraldehyde Biochemistry Models Biological Catalysis Substrate Specificity Sulfolobus chemistry.chemical_compound Glucose dehydrogenase Pyruvic Acid Escherichia coli Amino Acid Sequence Cloning Molecular Molecular Biology Entner–Doudoroff pathway Chromatography High Pressure Liquid Aldehyde-Lyases chemistry.chemical_classification Gluconate dehydratase biology Base Sequence ved/biology Aldolase A Sulfolobus solfataricus Temperature Galactose Glucose 1-Dehydrogenase Cell Biology Sequence Analysis DNA Recombinant Proteins Oxygen Metabolic pathway Kinetics Enzyme Glucose chemistry Models Chemical biology.protein |
| Zdroj: | The Journal of biological chemistry. 278(36) |
| ISSN: | 0021-9258 |
| Popis: | The hyperthermophilic Archaeon Sulfolobus solfataricus metabolizes glucose by a non-phosphorylative variant of the Entner-Doudoroff pathway. In this pathway glucose dehydrogenase and gluconate dehydratase catalyze the oxidation of glucose to gluconate and the subsequent dehydration of gluconate to 2-keto-3-deoxygluconate. 2-Keto-3-deoxygluconate (KDG) aldolase then catalyzes the cleavage of 2-keto-3-deoxygluconate to glyceraldehyde and pyruvate. The gene encoding glucose dehydrogenase has been cloned and expressed in Escherichia coli to give a fully active enzyme, with properties indistinguishable from the enzyme purified from S. solfataricus cells. Kinetic analysis revealed the enzyme to have a high catalytic efficiency for both glucose and galactose. KDG aldolase from S. solfataricus has previously been cloned and expressed in E. coli. In the current work its stereoselectivity was investigated by aldol condensation reactions between D-glyceraldehyde and pyruvate; this revealed the enzyme to have an unexpected lack of facial selectivity, yielding approximately equal quantities of 2-keto-3-deoxygluconate and 2-keto-3-deoxygalactonate. The KDG aldolase-catalyzed cleavage reaction was also investigated, and a comparable catalytic efficiency was observed with both compounds. Our evidence suggests that the same enzymes are responsible for the catabolism of both glucose and galactose in this Archaeon. The physiological and evolutionary implications of this observation are discussed in terms of catalytic and metabolic promiscuity. |
| Databáze: | OpenAIRE |
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