The Cytochromes of Thermoplasma acidophilum

Holländer, R

doi:10.1099/00221287-108-1-165

Cited by 29 publications

(10 citation statements)

References 13 publications

(7 reference statements)

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“…These bacteria resemble culturable animal mycoplasmas in the class Mollicutes in that they are procaryotes lacking cell walls. However, basing a biosystematic classification on this simple morphological trait can be misleading, as is evidenced by the example of Thermoplasma acidophilum, which also lacks a cell wall and was initially classified with the Mollicutes but which has been shown through biochemical (7) and molecular (29) analyses to be an archaebacterium.…”

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confidence: 99%

16S rRNA sequence indicates that plant-pathogenic mycoplasmalike organisms are evolutionarily distinct from animal mycoplasmas

1989

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The plant-pathogenic mycoplasmalike organisms (MLOs) are so named because they lack cell wails. Many features that are essential to a definitive classffication remain uncharacterized, because these organisms have resisted attempts at in vitro culturing. To establish the taxonomic position of the MLOs, the DNA region containing the 16S rRNA gene from a representative of The plant-pathogenic mycoplasmalike organisms (MLOs) cause developmental disturbances in a wide array of economically important plants. Symptoms include yellowing and deformation of leaves and abnormalities such as sterile flowers and phyllody (3). Diseases caused by MLOs were thought for many years to be caused by viruses, but transmission electron microscopy indicated the presence of cell wall-less bacteria in the phloem, which implicates MLOs as the disease-causing agents. These bacteria resemble culturable animal mycoplasmas in the class Mollicutes in that they are procaryotes lacking cell walls. However, basing a biosystematic classification on this simple morphological trait can be misleading, as is evidenced by the example of Thermoplasma acidophilum, which also lacks a cell wall and was initially classified with the Mollicutes but which has been shown through biochemical (7) and molecular (29) analyses to be an archaebacterium.A more precise identification beyond the tentative designation MLO has not been possible because of the absence of information on critical features such as genome organization, nutritional requirements, and membrane composition of the MLOs (24). Such biological characterizations have been difficult, because the MLOs have not been amenable to in vitro culture (10). In an effort to provide molecular data which would be relevant to the question of the classification and evolutionary origin of the plant-pathogenic MLOs, the 16S rRNA gene and adjacent regions were cloned and sequenced from an MLO pathogen of Oenothera hookeri, the evening primrose.Previous analyses of 16S rRNA and 5S rRNA sequences and 16S rRNA oligonucleotide catalogs have shown that the members of the class Mollicutes are phylogenetically related to gram-positive bacteria (20,29,30). From this information, it has been postulated that the Mollicutes are derived by degenerative evolution from the clostridia. In addition to having rRNA sequence similarities, the Mollicutes resemble * Corresponding author. (23). In this report, we present sequence data which point to the phylogenetic origin of this cell wall-less bacterium. MATERIALS AND METHODSBacterial strains and plasmids. Escherichia coli TB1 was used as the host for cloning experiments with pUC19, while E. coli JM107 was used as the host for M13mpl8 and M13mpl9, which were used for sequencing. Plasmid pMC5, which was kindly provided by G. Glaser, is a derivative of pBR325, which carries part of the 16S rRNA gene and the entire 23S rRNA and 5S rRNA genes of Mycoplasma capricolum, a goat pathogen (1).Preparation of plasmid and bacteriophage DNAs. Plasmid DNA was prepared by methods described by Maniat...

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confidence: 99%

16S rRNA sequence indicates that plant-pathogenic mycoplasmalike organisms are evolutionarily distinct from animal mycoplasmas

1989

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“…In the corresponding enzyme of Picrophilus, several components were absent (e.g., A″ and E) and the enzyme does not crossreact in immunodiffusion assays with antibodies against the Thermoplasma enzyme (Schleper et al, 1995). The respiratory chain of Thermoplasma contains at least one b-type cytochrome (Belly et al, 1973;Holländer, 1978;Searcy and Whatley, 1982) and several quinones (Holländer et al, 1977;Collins and Langworthy, 1983). Among the quinones, a characteristic compound called "thermoplasmaquinone" was found, which was not detected in other Archaea.…”

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confidence: 85%

Thermoplasmatales

Huber¹,

Stetter²

2006

The Prokaryotes

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“…A proton motive force in the range 190-240 mV could be measured, indicating the presence of proton pumps associated with a respiratory chain [6]. The cytochrome composition of 7: ucidophilum is still a matter of discussion.The first studies revealed the presence of c-and o-type cytochromes [8], whereas in subsequent investigations the presence of additional cytochromes of the 6and d-type was reported [9]. In a further study, only b-type cytochromes were detected [lo].…”

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“…The first studies revealed the presence of c-and o-type cytochromes [8], whereas in subsequent investigations the presence of additional cytochromes of the 6and d-type was reported [9]. In a further study, only b-type cytochromes were detected [lo].…”

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EPR Characterization of an Archaeal Succinate Dehydrogenase in the Membrane-Bound State

Anemüller¹,

Hettmann²,

Moll³

et al. 1995

Eur J Biochem

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The membrane-bound succinate dehydrogenase from the thermoacidophilic archaeon Thermoplasma acidophilum was characterized by EPR spectroscopy and its functional properties were determined. The highest turnover values of succinate dehydrogenase activity were observed at pH 7.4, which is somewhat above the internal pH value of T. acidophilum. The temperature optimum of the reaction was determined as 78 degrees C and the Km value for succinate using phenazine methosulfate as the electron acceptor at 53 degrees C was 0.32 mM. The membrane-bound enzyme was able to reduce the artificial electron acceptors phenazine methosulfate, N,N,N',N'-tetramethyl-p-phenylenediamine, and 2,6-dichloroindophenol. Succinate oxidation was coupled to oxygen consumption in a completely 2-n-heptyl-4-hydroxyquinoline-N-oxide-sensitive manner. In the oxidized state, T. acidophilum membranes exhibited an almost isotropic EPR spectrum with g-values at gz = 2.017, gy = 2.000, and gx = 1.968 that were assigned to a [3Fe-4S]1+ cluster (S3). Upon reduction with succinate, the membranes displayed a spectrum characteristic of 2Fe-2S clusters (S1), with g-values at gz = 2.029, gy = 1.935, and gx = 1.915. In the dithionite-reduced state, additional resonances can be observed. An axial component, with g-values at gz = 2.057, gy = 1.917, and gx = 1.917 was assigned to a [4Fe-4S]1+ cluster. The saturation behaviour of the S1 cluster was strongly altered in the dithionite-reduced form, thus indicating spin-spin interaction between the S1 center and another paramagnetic center, possibly cluster S2. In both the succinate and the dithionite-reduced membranes, parallel-mode EPR spectra displayed a resonance at g = 14, which may be due to a transition of the S = 2 multiplet of the reduced 3Fe-4S cluster. Spin quantitation yielded a relative stoichiometry of cluster S1 to cluster S3 of 1:1. The results obtained by EPR spectroscopy indicated that the characteristic iron-sulfur cluster S1 [2Fe-2S], S2 [4Fe-4S], and S3 [3Fe-4S], were also present in this archaeal succinate dehydrogenase. EPR redox titrations of T. acidophilum membranes at pH 5.5 yielded a reduction potential of +60 +/- 20 mV for cluster S3 and of +68 +/- 20 mV for cluster S1. The axial [4Fe-4S]2+/1+ center had a reduction potential of -210 +/- 20 mV.

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The Cytochromes of Thermoplasma acidophilum

Cited by 29 publications

References 13 publications

16S rRNA sequence indicates that plant-pathogenic mycoplasmalike organisms are evolutionarily distinct from animal mycoplasmas

16S rRNA sequence indicates that plant-pathogenic mycoplasmalike organisms are evolutionarily distinct from animal mycoplasmas

Thermoplasmatales

EPR Characterization of an Archaeal Succinate Dehydrogenase in the Membrane-Bound State

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