Genomic View of Energy Metabolism in Ralstonia eutropha H16Cramm R.
Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
Ralstonia eutropha is a strictly respiratory facultative lithoautotrophic β-proteobacterium. In the absence of organic substrates, H2 and CO2 are used as sole sources of energy and carbon. In the absence of oxygen, the organism can respire by denitrification. The recent determination of the complete genome sequence of strain H16 provides the opportunity to reconcile the results of previous physiological and biochemical studies in light of the coding capacity. These analyses revealed genes for several isoenzymes, permit assignment of well-known physiological functions to previously unidentified genes, and suggest the presence of unknown components of energy metabolism. The respiratory chain is fueled by two NADH dehydrogenases, two uptake hydrogenases and at least three formate dehydrogenases. The presence of genes for five quinol oxidases and three cytochrome oxidases indicates that the aerobic respiration chain adapts to varying concentrations of dioxygen. Several additional components may act in balancing or dissipation of redox energy. Paralogous sets of nitrate reductase and nitric oxide reductase genes result in enzymatic redundancy for denitrification.
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Published online: October 29, 2008
Number of Print Pages : 15
Number of Figures : 1, Number of Tables : 1, Number of References : 129
Journal of Molecular Microbiology and Biotechnology
Vol. 16, No. 1-2, Year 2009 (Cover Date: October 2008)
Journal Editor: Saier Jr. M.H. (La Jolla, Calif.)
ISSN: 1464–1801 (Print), eISSN: 1660–2412 (Online)
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