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  • 1
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    The electron transport system of Alcaligenes eutrophus H16 (1991)
    Springer
    Details
    Publication Date: 1991-04-01
    Print ISSN: 0302-8933
    Electronic ISSN: 1432-072X
    Topics: Biology
    Published by Springer
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  • 2
    Electronic Resource
    Electronic Resource
    The electron transport system of Alcaligenes eutrophus H16 (1991)
    Springer
    Archives of microbiology 155 (1991), S. 382-390 
    Details
    ISSN: 1432-072X
    Keywords: Alcaligenes eutrophus H16 ; Paracoccus denitrificans ; Electron transport system ; Cytochrome composition ; Ubiquinol-cytochrome c oxidoreductase ; Terminal oxidases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The electron transport system of autotrophically grown Alcaligenes eutrophus H16 has been investigated by spectroscopic and thermodynamic approaches. The results have been interpreted as evidence that isolated membranes contain a branched respiratory chain composed of three c-type haems (E m,7=+160 mV, + 170 mV, and + 335 mV), five b-type haems (E m,7=+ 5 mV, + 75 mV, + 205 mV, + 300 mV, and + 405 mV), two (possibly three) a-type haems [E m,7= + 255 mV, + 350 mV, (+ 420 mV)], and nne d-type haem. EPR-analysis of the signals at g=1.93, g=2.02, and g=1.90 revealed the presence of iron-sulphur centres diagnostic of complexes I (NADH dehydrogenase), II (succinate dehydrogenase), and III (ubiquinol/cytochrome c oxidoreductase). The low potential b haems (+ 5 mV and + 75 mV) plus the Rieske protein (g=1.90, E m,7=+ 280 mV), thought to be part of an orthodox bc 1 complex, were present in low amounts as compared to their counterparts in membranes from Paracoccus denitrificans. CO-difference spectra in the presence of either succinate, NADH, hydrogen, ascorbate/TMPD, and/or dithionite as reductants, suggested the existance of four different oxidases composed by bo-, cb-, a-, and d-type haems. It is concluded that in contrast to other chemolithotrophes, e.g. P. denitrificans, autotrophic growth of Alcaligenes eutrophus utilizes a respiratory system in which the bc 1 complex containing pathway is only partially involved in electron transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00243459
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  • 3
    Electronic Resource
    Electronic Resource
    The electron transport system of Alcaligenes eutrophus H16 (1991)
    Springer
    Archives of microbiology 155 (1991), S. 436-443 
    Details
    ISSN: 1432-072X
    Keywords: Alcaligenes eutrophus H16 ; Electron transport system ; Cytochrome c defective mutant RK1 ; Paracoccus denitrificans ; Respiratory enzyme activities ; Oxidases ; Dehydrogenases ; Myxothiazol ; Antimycin A ; Cyanide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a previous work (Kömen et al. 1991) it has been concluded that membrane fragments isolated from autotrophically grown Alcaligenes eutrophus H16 contain several iron-sulphur centres along with haems of a-, b-, c-, and d-type. These redox components have been proposed to be part of a branched respiratory chain leading to multiple membrane bound oxidases. Here, some of the respiratory activities catalyzed by membrane fragments from wild type cells of A. eutrophus (H16) and, for comparison, Paracoccus denitrificans, have been investigated through the use of electron transport inhibitors. Cyanide (CN-) titration curves indicated that in A. eutrophus H16 oxidation of succinate and H2 preferentially proceeds via the cytochrome c oxidase(s) branch (I 50=2 · 10-5 M) whereas the NADH dependent respiration started being inhibited at higher CN- concentrations (I 50=5 · 10-4 M). In membranes isolated from both, cells harvested at late growth-phase (OD 12) and from a mutant deficient in cytochrome c oxidase activity (A. eutrophus RK1), respiration was insensitive to low CN- concentrations (〈 10-4 M), and it was sustained by the high catalytic activities of two quinol oxidases. These alternative oxidases of b- (formally o-) and d-type showed different sensitivities to KCN (I 50=10-3 M and 10-2 M, respectively). Interestingly, the cytochrome c oxidase(s) dependent respiration of H16 membranes was insensitive to antimycin A but largely inhibited by myxothiazol (10-6 M). This, and previous work (Kömen et al. 1991), suggest that although the respiratory chain of A. eutrophus is endowed with a putative bc 1 complex, its biochemical nature and role in respiration of this organism are apparently different from those of P. denitrificans. The peculiarity of the respiratory chain of A. eutrophus is confirmed by the rotenone insensitivity of the NADH oxidation in both protoplasts and membrane fragments from wild type and soluble hydrogenase deficient cells (HF14 and HF160). A tentative model of the respiratory chain of autotrophically grown A. eutrophus is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00244958
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  • 4
    Electronic Resource
    Electronic Resource
    Methanol and methylamine utilization result from mutational events in Thiosphaera pantotropha (1993)
    Springer
    Archives of microbiology 159 (1993), S. 364-371 
    Details
    ISSN: 1432-072X
    Keywords: Catabolic mutants ; Cytochrome analysis ; Methanol ; Methylamine ; Organoautotrophy ; Thiosphaera pantotropha
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract With choline as carbon source Thiosphaera pantotropha GB17 grew with a doubling time (td) of 6 h. The cellular yield was 55.8 g dry cell weight per mol of choline, indicating that its methyl moieties were used for growth. However, T. pantotropha was unable to grow with methanol or with methylamine as carbon source. Mutants were isolated from liquid or from solid media able to grow with methanol (Mox+) as carbon or methylamine as nitrogen source (Mam+). The Mox+ mutant GB17M grew with a mean td of 11.7h and a growth yield of 8.9 g dry cell weight per mol of methanol. Diauxic growth of strain GB17M was observed with mixtures of pyruvate and methanol as substrates in batch culture. Methanol led to the formation of methanol dehydrogenase, formate dehydrogenase, ribulosebisphosphate carboxylase and of a soluble cytochrome c-551.5. Tn5-insertional mutants defective in the thiosulfate oxidizing enzyme system or in hydrogenase acquired the Mox+ phenotype. However, Tn5-insertional mutants defective in either a c-type cytochrome or the molybdenum cofactor did not mutate to the Mox+ phenotype, indicating common functions in thiosulfate and in methanol metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290919
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  • 5
    Electronic Resource
    Electronic Resource
    Hydrogenase mutants of Alcaligenes eutrophus H16 show alterations in the electron transport system (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 96 (1992), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Mutations in the genes coding for the soluble and the membrane-bound hydrogenase of Alcaligenes eutrophus strain H16 significantly affected the expression of respiratory chain components. In lithoautotrophically grown wild type cells electron flow mainly proceeded via the cytochrome c oxidases. Mutants defective in the membrane-bound hydrogenase contained a 2- to 3-fold higher cytochrome a content than the wild type and cytochrome c oxidase of the aa3-type was preferentially used by these cells for substrate oxidation. Mutants impaired in the soluble hydrogenase revealed slow growth on hydrogen, presumably due to inefficient reverse electron flow mechanisms which provide the cells with NADH for autotrophic CO2-fixation. In this class of mutants the two quinol oxidases of the o- and d-type in addition to the co-type oxidase were the predominant electron-transport branches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1992.tb05412.x
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