d-Xylose Degradation Pathway in the Halophilic Archaeon Haloferax volcanii
| Autor: | Tobias Fuhrer, Henning Zaiss, Peter Schönheit, Jörg Soppa, Ulrike Johnsen, Uwe Sauer, Michael Dambeck |
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| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
Cell Extracts
ved/biology.organism_classification_rank.species Molecular Sequence Data Biology Xylose Biochemistry Genes Archaeal chemistry.chemical_compound Xylose metabolism Amino Acid Sequence Molecular Biology Haloferax volcanii Hydro-Lyases Oligonucleotide Array Sequence Analysis Sequence Deletion Xylulose ved/biology Sulfolobus solfataricus Cell Biology biology.organism_classification Citric acid cycle Metabolism and Bioenergetics chemistry Dehydratase Xylonate dehydratase |
| Popis: | The pathway of D-xylose degradation in archaea is unknown. In a previous study we identified in Haloarcula marismortui the first enzyme of xylose degradation, an inducible xylose dehydrogenase (Johnsen, U., and Schonheit, P. (2004) J. Bacteriol. 186, 6198-6207). Here we report a comprehensive study of the complete D-xylose degradation pathway in the halophilic archaeon Haloferax volcanii. The analyses include the following: (i) identification of the degradation pathway in vivo following (13)C-labeling patterns of proteinogenic amino acids after growth on [(13)C]xylose; (ii) identification of xylose-induced genes by DNA microarray experiments; (iii) characterization of enzymes; and (iv) construction of in-frame deletion mutants and their functional analyses in growth experiments. Together, the data indicate that D-xylose is oxidized exclusively to the tricarboxylic acid cycle intermediate alpha-ketoglutarate, involving D-xylose dehydrogenase (HVO_B0028), a novel xylonate dehydratase (HVO_B0038A), 2-keto-3-deoxyxylonate dehydratase (HVO_B0027), and alpha-ketoglutarate semialdehyde dehydrogenase (HVO_B0039). The functional involvement of these enzymes in xylose degradation was proven by growth studies of the corresponding in-frame deletion mutants, which all lost the ability to grow on d-xylose, but growth on glucose was not significantly affected. This is the first report of an archaeal D-xylose degradation pathway that differs from the classical D-xylose pathway in most bacteria involving the formation of xylulose 5-phosphate as an intermediate. However, the pathway shows similarities to proposed oxidative pentose degradation pathways to alpha-ketoglutarate in few bacteria, e.g. Azospirillum brasilense and Caulobacter crescentus, and in the archaeon Sulfolobus solfataricus. |
| Databáze: | OpenAIRE |
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