Molecular characterization of the sor gene, which encodes the sulfur oxygenase/reductase of the thermoacidophilic Archaeum Desulfurolobus ambivalens

Kletzin, Arnulf

doi:10.1128/jb.174.18.5854-5859.1992

Cited by 71 publications

(53 citation statements)

References 35 publications

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“…Although there are archaebacterial mRNAs consisting of a leader sequence with a ribosome binding site motif similar to that of bacteria (9), a large number of archaebacterial messages with very short leaders or no leader have been identified (14,28,30,31). From this finding arises the question of how translation initiation and interaction with ribosomes take place.…”

Section: Resultsmentioning

confidence: 91%

A succinate dehydrogenase with novel structure and properties from the hyperthermophilic archaeon Sulfolobus acidocaldarius: genetic and biophysical characterization

1997

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The sdh operon of Sulfolobus acidocaldarius DSM 639 is composed of four genes coding for the 63.1-kDa flavoprotein (SdhA), the 36.5-kDa iron-sulfur protein (SdhB), and the 32.1-kDa SdhC and 14.1-kDa SdhD subunits. The four structural genes of the sdhABCD operon are transcribed into one polycistronic mRNA of 4.2 kb, and the transcription start was determined by the primer extension method to correspond with the first base of the ATG start codon of the sdhA gene. The S. acidocaldarius SdhA and SdhB subunits show characteristic sequence similarities to the succinate dehydrogenases and fumarate reductases of other organisms, while the SdhC and SdhD subunits, thought to form the membrane-anchoring domain, lack typical transmembrane ␣-helical regions present in all other succinate:quinone reductases (SQRs) and quinol:ifumarate reductases (QFRs) so far examined. Moreover, the SdhC subunit reveals remarkable 30% sequence similarity to the heterodisulfide reductase B subunit of Methanobacterium thermoautotrophicum and Methanococcus jannaschii, containing all 10 conserved cysteine residues. Electron paramagnetic resonance (EPR) spectroscopic studies of the purified enzyme as well as of membranes revealed the presence of typical S1 [2Fe2S] and S2 [4Fe4S] clusters, congruent with the deduced amino acid sequences. In contrast, EPR signals for a typical S3 [3Fe4S] cluster were not detected. However, EPR data together with sequence information implicate the existence of a second [4Fe4S] cluster in S. acidocaldarius rather than a typical [3Fe4S] cluster. These results and the fact that the S. acidocaldarius succinate dehydrogenase complex reveals only poor activity with caldariella quinone clearly suggest a unique structure for the SQR of S. acidocaldarius, possibly involving an electron transport pathway from the enzyme complex into the respiratory chain different from those for known SQRs and QFRs.Succinate:quinone reductase (SQR), a membrane-bound enzyme complex and component of the respiratory chain (complex II) of all aerobic organisms, catalyzes the oxidation of succinate to fumarate in the tricarboxylic acid cycle and transfers the electrons directly to quinones in the membrane. The reverse reaction, the reduction of fumarate, which is the last step in fumarate respiration of anaerobic or facultative anaerobic organisms, is catalyzed by quinol:fumarate reductase (QFR). The two enzyme complexes are very similar with regard to composition of subunits, prosthetic groups, and probably structure (2, 24). SQRs and QFRs are composed of three or four subunits of which the largest protein is a flavoprotein (M r of 65,000 to 79,000) carrying covalently bound 8-␣-N(3)-histidyl-flavin adenine dinucleotide (FAD). An iron-sulfur protein (M r of 25,000 to 37,000) together with this flavoprotein subunit represents the peripheral part of the enzyme complex. The iron-sulfur protein is suggested to contain three different types of iron-sulfur clusters, each equimolar with FAD. Magnetic circular dichroism and electron paramagnetic resonance...

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Section: Resultsmentioning

confidence: 91%

A succinate dehydrogenase with novel structure and properties from the hyperthermophilic archaeon Sulfolobus acidocaldarius: genetic and biophysical characterization

1997

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“…(iii) No reducing equivalents for cellular respiration can be obtained from reduced substrates. (iv) The obligate oxidation of elemental sulfur to H 2 SO 4 is the only source of reducing equivalents which may provide electrons for the reduction of the ferredoxin/NADH pool as well as for the pool of caldariella quinol as the substrate of the terminal oxidase; none of these pathways is known in any detail, though a sulfoxygenase located in the cytoplasm has been characterized (30,31). (v) Equivalents to the respiratory complexes I and III of organotrophic organisms apparently are absent (55,56).…”

Section: Discussionmentioning

confidence: 99%

The terminal quinol oxidase of the hyperthermophilic archaeon Acidianus ambivalens exhibits a novel subunit structure and gene organization

et al. 1997

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A terminal quinol oxidase has been isolated from the plasma membrane of the crenarchaeon Acidianus ambivalens (DSM 3772) (formerly Desulfurolobus ambivalens), cloned, and sequenced. The detergent-solubilized complex oxidizes caldariella quinol at high rates and is completely inhibited by cyanide and by quinolone analogs, potent inhibitors of quinol oxidases. It is composed of at least five different subunits of 64.9, 38, 20.4, 18.8, and 7.2 kDa; their genes are located in two different operons. doxB, the gene for subunit I, is located together with doxC and two additional small open reading frames (doxE and doxF) in an operon with a complex transcription pattern. Two other genes of the oxidase complex (doxD and doxA) are located in a different operon and are cotranscribed into a common 1.2-kb mRNA. Both operons exist in duplicate on the genome of A. ambivalens. Only subunit I exhibits clear homology to other members of the superfamily of respiratory heme-copper oxidases; however, it reveals 14 transmembrane helices. In contrast, the composition of the accessory proteins is highly unusual; none is homologous to any known accessory protein of cytochrome oxidases, nor do homologs exist in the databases. DoxA is classified as a subunit II equivalent only by analogy of molecular size and hydrophobicity pattern to corresponding polypeptides of other oxidases. Multiple alignments and phylogenetic analysis of the heme-bearing subunit I (DoxB) locate this oxidase at the bottom of the phylogenetic tree, in the branch of heme-copper oxidases recently suggested to be incapable of superstoichiometric proton pumping. This finding is corroborated by lack of the essential amino acid residues delineating the putative H ؉ -pumping channel. It is therefore concluded that A. ambivalens copes with its strongly acidic environment simply by an extreme turnover of its terminal oxidase, generating a proton gradient only by chemical charge separation.

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“…The two proteins probably function identically and produce sulfite, hydrogen sulfide, and thiosulfate from sulfur and molecular oxygen (equation 8). No link to energy metabolism has been reported (38), and the significance of a sulfur oxygenase-reductase in energy metabolism is not clear. This enzyme has not been detected in Bacteria.…”

Section: Sox Systems Of Other Sulfur-oxidizing Bacteriamentioning

confidence: 99%

“…The reactions, however, do not involve oxidation of sulfur to sulfate. From Acidianus brierleyi a sulfur oxygenase was described (17), and from Acidianus ambivalens a sulfur oxygenase-reductase was described (37,38). The two proteins probably function identically and produce sulfite, hydrogen sulfide, and thiosulfate from sulfur and molecular oxygen (equation 8).…”

Section: Sox Systems Of Other Sulfur-oxidizing Bacteriamentioning

confidence: 99%

Oxidation of Reduced Inorganic Sulfur Compounds by Bacteria: Emergence of a Common Mechanism?

Friedrich

Röther

Bardischewsky

et al. 2001

Appl Environ Microbiol

584

519

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THE SULFUR-OXIDIZING PROKARYOTESBiological oxidation of hydrogen sulfide to sulfate is one of the major reactions of the global sulfur cycle. Reduced inorganic sulfur compounds (referred to below as sulfur) are exclusively oxidized by prokaryotes, and sulfate is the major oxidation product. Sulfur oxidation in members of the Eukarya is mediated by lithoautotrophic bacterial endosymbionts (44).The sulfur-oxidizing prokaryotes are phylogenetically diverse ( Fig. 1). In the domain Archaea aerobic sulfur oxidation is restricted to members of the order Sulfolobales (21, 58), and in the domain Bacteria sulfur is oxidized by aerobic lithotrophs or by anaerobic phototrophs. The nonphototrophic obligate anaerobe Wolinella succinogenes oxidizes hydrogen sulfide to polysulfide during fumarate respiration (41). The ecology, physiology, and biochemistry of sulfur-oxidizing bacteria have been reviewed previously. The neutrophilic chemolithotrophic bacteria have been reviewed by Kelly et al. (31,32,35) and Takakuwa (63), the acidophilic sulfur-oxidizing bacteria have been reviewed by Harrison (23) and Pronk et al. (46), and the molecular genetics of Acidithiobacillus ferrooxidans has been reviewed by Rawlings and Kusano (49). The sulfur metabolism of phototrophic bacteria has been reviewed by Brune (9,10) and Trüper and Fischer (65). The physiology and genetics of both phototrophic and lithotrophic sulfur-oxidizing prokaryotes have been discussed recently (18).Prokaryotes oxidize hydrogen sulfide, sulfur, sulfite, thiosulfate, and various polythionates under alkaline (57), neutral, or acidic conditions (23). Aerobic sulfur-oxidizing prokaryotes belong to genera like

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Molecular characterization of the sor gene, which encodes the sulfur oxygenase/reductase of the thermoacidophilic Archaeum Desulfurolobus ambivalens

Cited by 71 publications

References 35 publications

A succinate dehydrogenase with novel structure and properties from the hyperthermophilic archaeon Sulfolobus acidocaldarius: genetic and biophysical characterization

A succinate dehydrogenase with novel structure and properties from the hyperthermophilic archaeon Sulfolobus acidocaldarius: genetic and biophysical characterization

The terminal quinol oxidase of the hyperthermophilic archaeon Acidianus ambivalens exhibits a novel subunit structure and gene organization

Oxidation of Reduced Inorganic Sulfur Compounds by Bacteria: Emergence of a Common Mechanism?

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