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  • 1
    Electronic Resource
    Electronic Resource
    Purification of cytoplasmic membranes and outer membranes from Proteus mirabilis (1973)
    Springer
    Archives of microbiology 93 (1973), S. 311-325 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A crude cell envelope suspension has been prepared from Proteus mirabilis after osmotic shock of penicillin-induced spheroplasts. Employing discontinuous sucrose gradients this cell envelope suspension can be fractionated into four fractions. Besides a pellet of remaining spheroplasts and an intermediate fraction with mixed composition a highly purified cytoplasmic membrane fraction and an outer membrane fraction have been obtained. The cytoplasmic membrane fraction is not contaminated with mucopeptide or outer membrane material. It has a buoyant density of 1.13 g/ml and a protein content of 38%. The specific activities of formate dehydrogenase and nitrate reductase and the content of cytochrome b1 have increased sixfold in comparison with the crude cell envelope suspension. The outer membrane fraction contains only few contaminations with cytoplasmic membrane components and with mucopeptide. The gradient fractions have been characterized by electron microscopy and by polyacrylamide gel electrophoresis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427928
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  • 2
    Electronic Resource
    Electronic Resource
    Solubilization and purification of a cytoplasmic membrane bound enzyme catalyzing tetrathionate and thiosulphate reduction in Proteus mirabilis (1974)
    Springer
    Archives of microbiology 98 (1974), S. 19-30 
    Details
    ISSN: 1432-072X
    Keywords: Tetrathionate Reductase ; Thiosulphate Reductase ; Anaerobic Respiration ; Cytoplasmic Membrane ; Enzyme Purification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Solubilization of cytoplasmic membrane bound tetrathionate and thiosulphate reductase was accomplished without detergents by repeated extraction of a purified cytoplasmic membrane suspension with tert-amyl alcohol. On homokinetic sucrose gradients both solubilized reductase activities banded in single peaks in the same fractions. A sedimentation constant of 6.9 Svedbergs was calculated using catalase as indicator enzyme. Further purification was obtained on an electro focusing column. Again both reductase activities banded as a single peak in the same fractions. It can be concluded that both have an isoelectric point of 5.22. It was demonstrated on polyacrylamide gels that the peak fractions contained virtually one protein component, which catalyzes tetrathionate reduction as well as thiosulphate reduction. It was concluded that Proteus mirabilis has only one enzyme for both enzymatic functions. From polyacrylamide gel electrophoresis in 0.1% sodium dodecyl sulphate it appeared that this enzyme consists of two subunits with molecular weights of approx. 43 000 and 90 000 daltons. The complete enzyme has thus a molecular weight of approx. 133 000 daltons. Protein profiles of cytoplasmic membranes isolated after various growth conditions suggest that the smaller subunit of this enzyme is present after anaerobic growth in the presence of KNO3 in spite of repression of the complete enzyme under this growth condition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425264
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  • 3
    Electronic Resource
    Electronic Resource
    Fumarate reduction inProteus mirabilis (1976)
    Springer
    Archives of microbiology 110 (1976), S. 195-206 
    Details
    ISSN: 1432-072X
    Keywords: Fumarate reductase ; Electron transport ; Cytochromes-Inhibition: HQNO, antimycin A ; Proteus mirabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Proteus mirabilis formed fumarate reductase under anaerobic growth conditions. The formation of this reductase was repressed under conditions of growth during which electron transport to oxygen or to nitrate is possible. In two of three tested chlorateresistant mutant strains of the wild type, fumarate reductase appeared to be affected. 2. Cytoplasmic membrane suspensions isolated from anaerobically grownP. mirabilis oxidized formate and NADH with oxygen and with fumarate, too. 3. Spectral investigation of the cytoplasmic membrane preparation revealed the presence of (probably at least two types of) cytochromeb, cytochromea 1 and cytochromed. Cytochromeb was reduced by NADH as well as by formate to approximately 80%. 4. 2-n-Heptyl-4-hydroxyquinoline-N-oxide and antimycin A inhibited oxidation of both formate and NADH by oxygen and fumarate. Both inhibitors increased the level of the formate/oxygen steady state and the formate/fumarate steady state. 5. The site of inhibition of the respiratory activity by both HQNO and antimycin A was located at the oxidation side of cytochromeb. 6. The effect of ultraviolet-irradiation of cytoplasmic membrane suspensions on oxidation/reduction phenomena suggested that the role of menaquinone is more exclusive in the formate/fumarate pathway than in the electron transport route to oxygen. 7. Finally, the conclusion has been drawn that the preferential route for electron transport from formate and from NADH to fumarate (and to oxygen) includes cytochromeb as a directly involved carrier. A hypothetical scheme for the electron transport in anaerobically grownP. mirabilis is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690228
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of purified nitrate reductase A and chlorate reductase C from Proteus mirabilis (1976)
    Springer
    Archives of microbiology 111 (1976), S. 25-35 
    Details
    ISSN: 1432-072X
    Keywords: Nitrate reductase ; Chlorate reductase ; Anaerobic Respiration ; Proteus mirabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrate reductase A has been solubilized from purified cytoplasmic membranes by extraction with terl-amyl alcohol. The resulting aqueous solution contained monomeric reductase which polymerized slowly to dimers and tetramers with sedimentation coefficients of respectively 10.5, 16 and 23 Svedbergunits. The polymerization could be stopped to some extent by addition of a small amount of Triton X-100. These distinct entities of nitrate reductase A were separable on electro-focusing, DEAE-column chromatography and polyacrylamide gel electrophoresis, and have been proved to consist of similar subunits with molecular weights of 104000, 63000, and 56000 daltons. The molecular weights of monomeric nitrate reductase A was found to be about 240000 daltons. Chlorate reductase C has been solubilized by a similar procedure, resulting in only monomeric enzyme. Chlorate reductase C exhibited a sedimentation coefficient of 7.7 Svedbergunits, an isoelectric point of pH=4.55 and a molecular weight of approx. 180000 daltons. It was found to consist of three subunits with molecular weights of 75000, 63000 and 56000 daltons. The latter two subunits are most probably common in nitrate reductase A and chlorate reductase C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446546
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  • 5
    Electronic Resource
    Electronic Resource
    Molybdenum cofactor from the cytoplasmic membrane of Proteus mirabilis (1982)
    Springer
    Archives of microbiology 133 (1982), S. 283-288 
    Details
    ISSN: 1432-072X
    Keywords: Molybdenum cofactor ; Pterines ; High performance liquid chromatography ; Chlorate resistant mutant ; Xanthine oxidase ; Proteus mirabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molybdenum cofactor was extracted from membranes of Proteus mirabilis by three methods: acidification, heat treatment and heat treatment in the presence of sodium-dodecylsulphate (SDS). Extracts prepared by the latter method contained the highest concentration of molybdenum cofactor. In these extracts molybdenum cofactor was present in a low molecular weight form. It could not penetrate an YM-2 membrane during ultrafiltration suggesting a molecular weight above 1000. During aerobic incubation of cofactor extracts from membranes at least four fluorescent species were formed as observed in a reversed-phase high performance liquid chromatography (HPLC) system. The species in the first peak was inhomogeneous while the species in the others seem to be homogenous. In water, all fluorescent products had an excitation maximum at 380 nm and an emission maximum at 455 nm. Their absorption spectra showed maxima at around 270 nm and 400 nm. Fluorescent compounds present in the first peak could penetrate an YM-2 membrane during ultrafiltration, whereas the compounds in the other peaks hardly did. Using xanthine oxidase from milk as source of molybdenum cofactor apparently identical cofactor species were found. Cytoplasmic nor membrane extracts of the chlorate resistant mutant chl S 556 of P. mirabilis could complement nitrate reductase of Neurospora crassa nit-1 in the presence of 20 mM molybdate. However, fluorescent species with identical properties as found for the wild-type were formed during aerobic incubation of extracts from membranes of this mutant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00521291
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  • 6
    Electronic Resource
    Electronic Resource
    The influence of growth conditions on the synthesis of molybdenum cofactor in Proteus mirabilis (1981)
    Springer
    Archives of microbiology 130 (1981), S. 44-49 
    Details
    ISSN: 1432-072X
    Keywords: Molybdenum cofactor ; Tungstate ; Chlorate resistant mutant ; Proteus mirabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell-free extracts of Proteus mirabilis were able to reconstitute NADPH-dependent assimilatory nitrate reductase in crude extracts of the Neurospora crassa mutant strain nit-1, lacking molybdenum cofactor. Molybdenum cofactor was formed in the cytoplasm of the bacterium even in the presence of oxygen during growth though under these conditions no molybdo enzymes are formed. As a consequence no cofactor could be released by acid treatment from membranes of cells grown aerobically. The amount of cofactor released from membranes of cells grown anaerobically under various conditions was proportional to the amount of molybdo enzymes formed. During growth in the presence of tungstate a cofactor, which lacks molybdenum, was found in the cytoplasm. For detection of this so-called demolybdo cofactor the presence of molybdate during reconstitution was essential. Moreover, the cytoplasmic cofactor pool in cells grown in the presence of tungstate appeared to be two to three times higher than in cells grown under similar conditions without tungstate. After anaerobic growth in the presence of tungstate, the inactive demolybdo reductases were shown to contain partly no cofactor and partly a demolybdo cofactor. The P. mirabilis chlorate resistant mutant S 556 did not contain molybdenum cofactor. In two other chl-mutants the cofactor activity was the same as in the wild type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00527070
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  • 7
    Electronic Resource
    Electronic Resource
    Reduction of tetrathionate, trithionate and thiosulphate, and oxidation of sulphide in Proteus mirabilis (1975)
    Springer
    Archives of microbiology 105 (1975), S. 135-142 
    Details
    ISSN: 1432-072X
    Keywords: Tetrathionate Reductase ; Trithionate Reductase ; Thiosulphate Reductase ; Sulphide Oxidation ; Anaerobic Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The reductase catalyzing the reduction of tetrathionate and thiosulphate in Proteus mirabilis is also concerned with the reduction of trithionate and the oxidation of sulphide. Tetrathionate is reduced to thiosulphate, thiosulphate to sulphite and sulphide, and trithionate is reduced to thiosulphate plus sulphite. The oxidation of sulphide in cell-free extracts proceeds most likely to polysulphanes or to elemental sulphur, depending on the conditions. The kinetics of the reduction of tetrathionate imply a simultaneous interaction of tetrathionate and thiosulphate on the reductase molecule. The reduction of tetrathionate is activated by thiosulphate causing a non-linear progress of this reaction. On the other hand the reduction of thiosulphate is completely blocked until tetrathionate has been depleted. The order of reduction in a mixture of thiosulphate and trithionate is imputed by the enzymatic constants of the reductase for both substrates. Therefore in cell-free extracts thiosulphate is reduced prior to trithionate and afterwards, when thiosulphate has been exhausted, trithionate and the produced thiosulphate are reduced simultaneously. Fast growing cells, however, reduce trithionate first since their intracellular redox potential is insulfficiently low to permit the reduction of any thiosulphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00447128
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  • 8
    Electronic Resource
    Electronic Resource
    The correlation between the protein composition of cytoplasmic membranes and the formation of nitrate reductase A, chlorate reductase C and tetrathionate reductase in Proteus mirabilis wild type and some chlorate resistant mutants (1976)
    Springer
    Archives of microbiology 111 (1976), S. 37-43 
    Details
    ISSN: 1432-072X
    Keywords: Nitrate reductase ; Chlorate reductase ; Tetrathionate reductase ; Cytoplasmic membranes ; Anaerobic respiration ; Proteus mirabilis ; Repression/derepression mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three genotypically different chlorate resistant mutants, chl I, chl II and chl III, appeared to lack completely nitrate reductase A, chlorate reductase C and tetrathionate reductase activity. Fumarate reductase is only partially affected in chl I and chl III and unaffected in chl II. Formate dehydrogenase is only partially diminished in chl II, hydrogenase is diminished in chl I and chl II and completely absent in chl III. Subunits of nitrate reductase A, chlorate reductase C and tetrathionate reductase have been identified in protein profiles of purified cytoplasmic membranes from the wild type and the three mutant strains, grown under various conditions. Only the presence and absence of the largest subunits of these enzymes appeared to be correlated with their repression and derepression in the wild type membranes. On the cytoplasmic membranes of the chl I and chl III mutants these subunits lack for the greater part. In the chl II mutant, however, these subunits are inserted in the membrane all together after anaerobic growth with or without nitrate. A model for the repression/derepression mechanism for the reductases has been proposed. It includes repression by cytochrome b components, whereas the redox-state of the nitrate reductase A molecule itself is also involved in its derepression under anaerobic conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446547
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  • 9
    Electronic Resource
    Electronic Resource
    The existence of an alternative electron-transfer pathway to the periplasmic nitrite reductase (cytochrome cd 1) in Paracoccus denitrificans (1993)
    Springer
    Archives of microbiology 159 (1993), S. 272-275 
    Details
    ISSN: 1432-072X
    Keywords: Cytochrome c ; Cytochrome c peroxidase ; Nitrite reductase ; Denitrification ; Paracoccus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of aerobically-grown wild-type cells of Paracoccus denitrificans to a decreased aeration caused parallel increases in both PMS/ascorbate and succinate-linked activities of nitrite reductase. By contrast, the expression of the succinate-linked activity was considerably delayed in an insertion mutant specifically lacking the periplasmic 15 kDa cytochrome c-550. In this case the observed activity followed very closely the content of a 40 kDa cytochrome c. A subcellular fraction enriched in a haemoprotein of a similar apparent molecular weight showed the activity of cytochrome c peroxidase and was able to restore the antimycin-sensitive electron transport from membrane vesicles to nitrite reductase. It is concluded that P. denitrificans possesses an alternative nitrite-reducing pathway involving the 40 kDa cytochrome c instead of cytochrome c-550. This pathway branches from the respiratory chain after the cytochrome bc 1 segment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248483
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  • 10
    Electronic Resource
    Electronic Resource
    The functional localization of cytochromes b in the respiratory chain of anaerobically grown Proteus mirabilis (1986)
    Springer
    Antonie van Leeuwenhoek 52 (1986), S. 105-116 
    Details
    ISSN: 1572-9699
    Keywords: Proteus mirabilis ; Cytochrome b ; Respiratory chain ; HQNO
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The functional localization of the cytochromes b found in anaerobically grown Proteus mirabilis was investigated. From light absorption spectra, scanned during uninhibited and HQNO-inhibited electron transport to various electron acceptors, it was concluded that all cytochromes b function between two HQNO inhibition sites, or more probably in a Q- or b-cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429313
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