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  • 1
    Electronic Resource
    Electronic Resource
    Primary structure and eubacterial relationships of the pyruvate:Ferredoxin oxidoreductase of the amitochondriate eukaryoteTrichomonas vaginalis (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 388-396 
    Details
    ISSN: 1432-1432
    Keywords: Hydrogenosome ; Molecular phylogeny ; Anaerobic protist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the eukaryotic unicellular organismTrichomonas vaginalis a key step of energy metabolism, the oxidative decarboxylation of pyruvate with the formation of acetyl-CoA, is catalyzed by the iron-sulfur protein pyruvate:ferredoxin oxidoreductase (PFO) and not by the almost-ubiquitous pyruvate dehydrogenase multienzyme complex. This enzyme is localized in the hydrogenosome, an organelle bounded by a double membrane. PFO and its closely related homolog, pyruvate: flavodoxin oxidoreductase, are enzymes found in a number of archaebacteria and eubacteria. The presence of these enzymes in eukaryotes is restricted, however, to a few amitochondriate groups. To gain more insight into the evolutionary relationships ofT. vaginalis PFO we determined the primary structure of its two genes (pfoA andpfoB). The deduced amino acid sequences showed 95% positional identity. Motifs implicated in related enzymes in liganding the Fe-S centers and thiamine pyrophosphate were well conserved. TheT. vaginalis PFOs were found to be homologous to eubacterial pyruvate: flavodoxin oxidoreductases and showed about 40% amino acid identity to these enzymes over their entire length. Lack of eubacterial PFO sequences precluded a comparison.pfoA andpfoB revealed a greater distance from related enzymes of Archaebacteria. The conceptual translation of the nucleotide sequences predicted an amino-terminal pentapeptide not present in the mature protein. This processed leader sequence was similar to but shorter than leader sequences noted in other hydrogenosomal proteins. These sequences are assumed to be involved in organellar targeting and import. The results underscore the unusual characteristics ofT. vaginalis metabolism and of their hydrogenosomes. They also suggest that in its energy metabolismT. vaginalis is closer to eubacteria than archaebacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01215186
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Primary structure and eubacterial relationships of the pyruvate:Ferredoxin oxidoreductase of the amitochondriate eukaryote Trichomonas vaginalis (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 388-396 
    Details
    ISSN: 1432-1432
    Keywords: Hydrogenosome ; Molecular phylogeny ; Anaerobic protist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the eukaryotic unicellular organism Trichomonas vaginalis a key step of energy metabolism, the oxidative decarboxylation of pyruvate with the formation of acetyl-CoA, is catalyzed by the iron-sulfur protein pyruvate:ferredoxin oxidoreductase (PFO) and not by the almost-ubiquitous pyruvate dehydrogenase multienzyme complex. This enzyme is localized in the hydrogenosome, an organelle bounded by a double membrane. PFO and its closely related homolog, pyruvate: flavodoxin oxidoreductase, are enzymes found in a number of archaebacteria and eubacteria. The presence of these enzymes in eukaryotes is restricted, however, to a few amitochondriate groups. To gain more insight into the evolutionary relationships of T. vaginalis PFO we determined the primary structure of its two genes (pfoA and pfoB). The deduced amino acid sequences showed 95% positional identity. Motifs implicated in related enzymes in liganding the Fe-S centers and thiamine pyrophosphate were well conserved. The T. vaginalis PFOs were found to be homologous to eubacterial pyruvate: flavodoxin oxidoreductases and showed about 40% amino acid identity to these enzymes over their entire length. Lack of eubacterial PFO sequences precluded a comparison. pfoA and pfoB revealed a greater distance from related enzymes of Archaebacteria. The conceptual translation of the nucleotide sequences predicted an amino-terminal pentapeptide not present in the mature protein. This processed leader sequence was similar to but shorter than leader sequences noted in other hydrogenosomal proteins. These sequences are assumed to be involved in organellar targeting and import. The results underscore the unusual characteristics of T. vaginalis metabolism and of their hydrogenosomes. They also suggest that in its energy metabolism T. vaginalis is closer to eubacteria than archaebacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00186551
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Lysosomes in Tetrahymena pyriformis I. Some properties and lysosomal localization of acid hydrolasesSupported by grant GB-2871 from the National Science Foundation. Performed with the skillful technical assistance of Miss Magdeleine Debbaudt to whom the authors are deeply grateful. (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 68 (1966), S. 165-175 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In homogenates of Tetrahymena pyriformis, five hydrolases  -  phosphatase, ribonuclease, deoxyribonuclease, proteinase, amylase  -  with acid pH optima were found. Over 75% of their activity is sedimentable with a centrifugal force of 250,000 g. min. Only 17% of the acid phosphatase and ribonuclease is active when assayed in the presence of 0.25 M sucrose at 0°. Exposure to a lowered osmotic pressure, freezing and thawing, and incubation at temperatures over 0° result in activation of the latent phosphatase and ribonuclease. After isopycnic centrifugation in a sucrose density gradient the hydrolases show a broad distribution which differs greatly from those of enzymes associated with mitochondria (succinate dehydrogenase) or with peroxisomes (catalase). The results are interpreted as evidence that the five acid hydrolases studied are localized in lysosomes which represent a distinct population of subcellular particles in Tetrahymena.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040680211
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    Paper (German National Licenses)
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