Different glycolytic pathways for glucose and fructose in the halophilic archaeon Halococcus saccharolyticus
| Autor: | Karina B. Xavier, Martina Selig, Peter Schönheit, Ulrike Johnsen, Helena Santos |
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| Rok vydání: | 2001 |
| Předmět: |
Magnetic Resonance Spectroscopy
Phosphofructokinase-1 Fructose 1 6-bisphosphatase Fructose Biochemistry Microbiology Fructokinases Halococcus chemistry.chemical_compound Genetics Glycolysis Kinase activity Molecular Biology Hydro-Lyases chemistry.chemical_classification Gluconate dehydratase biology General Medicine Kinetics Phosphotransferases (Alcohol Group Acceptor) Diauxic growth Biodegradation Environmental Glucose Enzyme chemistry Fructolysis biology.protein |
| Zdroj: | Archives of Microbiology. 175:52-61 |
| ISSN: | 1432-072X 0302-8933 |
| DOI: | 10.1007/s002030000237 |
| Popis: | The glucose and fructose degradation pathways were analyzed in the halophilic archaeon Halococcus saccharolyticus by 13C-NMR labeling studies in growing cultures, comparative enzyme measurements and cell suspension experiments. H. saccharolyticus grown on complex media containing glucose or fructose specifically 13C-labeled at C1 and C3, formed acetate and small amounts of lactate. The 13C-labeling patterns, analyzed by 1H- and 13C-NMR, indicated that glucose was degraded via an Entner-Doudoroff (ED) type pathway (100%), whereas fructose was degraded almost completely via an Embden-Meyerhof (EM) type pathway (96%) and only to a small extent (4%) via an ED pathway. Glucose-grown and fructose-grown cells contained all the enzyme activities of the modified versions of the ED and EM pathways recently proposed for halophilic archaea. Glucose-grown cells showed increased activities of the ED enzymes gluconate dehydratase and 2-keto-3-deoxy-gluconate kinase, whereas fructose-grown cells contained higher activities of the key enzymes of a modified EM pathway, ketohexokinase and fructose-1-phosphate kinase. During growth of H. saccharolyticus on media containing both glucose and fructose, diauxic growth kinetics were observed. After complete consumption of glucose, fructose was degraded after a lag phase, in which fructose-1-phosphate kinase activity increased. Suspensions of glucose-grown cells consumed initially only glucose rather than fructose, those of fructose-grown cells degraded fructose rather than glucose. Upon longer incubation times, glucose- and fructose-grown cells also metabolized the alternate hexoses. The data indicate that, in the archaeon H. saccharolyticus, the isomeric hexoses glucose and fructose are degraded via inducible, functionally separated glycolytic pathways: glucose via a modified ED pathway, and fructose via a modified EM pathway. |
| Databáze: | OpenAIRE |
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