Sulfide quinone reductase (SQR) activity in <i>Chlorobium</i>

Shahak, Yosepha; Arieli, B; Padan, Etana; Hauska, Günter

doi:10.1016/0014-5793(92)80230-e

Cited by 74 publications

(47 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Attempts to solubilize the SQR with 25 mM dodecylmaltoside yielded only 10% (12). Solubilization with 0.5% cholate yielded about 45% of the SQR activity, but it was unstable.…”

Section: Resultsmentioning

confidence: 99%

“…Solubilization with 0.5% cholate yielded about 45% of the SQR activity, but it was unstable. NaBr treatment extracted around 36% (12). Sonication (Sonifier B-12, Branson) of the chromatophores (40 W, 15 s, eight times with intervals of 30 s at 4°C) resulted in 30% loss of the total activity, and after the ultracentrifugation step less than 5% of the residual activity remained in the supernatant.…”

Section: Resultsmentioning

confidence: 99%

“…Recently we have demonstrated SQR activity in chromatophores of R. capsulatus and shown that sulfide oxidation is connected to the reduction of the cytochrome bc 1 complex via the ubiquinone pool (11). Furthermore we have purified the SQR from R. capsulatus (12,13), and the N-terminal amino acid sequences of this enzyme and that of O. limnetica were found highly homologous (3,13). Remarkably, all the expected fingerprint residues of the FAD binding domain (14,15) are conserved in the SQR of R. capsulatus and O. limnetica (3,13).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Sulfide-Quinone Reductase from Rhodobacter capsulatus

Schutz

Shahak

Padan

et al. 1997

Journal of Biological Chemistry

View full text Add to dashboard Cite

A sulfide-quinone oxidoreductase (SQR, EC 1.8.5..) has been purified to homogeneity from chromatophores of the non-sulfur purple bacterium Rhodobacter capsulatus DSM 155. It is composed of a single polypeptide with an apparent molecular mass of about 55 kDa, exhibiting absorption and fluorescence spectra typical for a flavoprotein and similar to the SQR from the cyanobacterium Oscillatoria limnetica.

show abstract

“…Attempts to solubilize the SQR with 25 mM dodecylmaltoside yielded only 10% (12). Solubilization with 0.5% cholate yielded about 45% of the SQR activity, but it was unstable.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Sulfide-Quinone Reductase from Rhodobacter capsulatus

Schutz

Shahak

Padan

et al. 1997

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…This enzyme was first isolated from thylakoids of the cyanobacterium Oscillatoria limnetica (Arieli et al, 1994). Since then, SQR activity has been investigated in a variety of phototrophic and chemotrophic bacteria including Chlorobium limicola (Shahak et al, 1992), Paracoccus denitrificans (Schutz et al, 1998) and Allochromatium vinosum (Reinartz et al, 1998) (for reviews see Griesbeck et al, 2002;Shahak et al, 1999). The sqr gene from the phototrophic bacterium Rhodobacter capsulatus has been isolated, sequenced, and expressed in Escherichia coli (Schutz et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Molecular analysis of the diversity of the sulfide : quinone reductase (sqr) gene in sediment environments

et al. 2008

View full text Add to dashboard Cite

Our newly designed primers were evaluated for the molecular analysis of specific groups of the sqr gene encoding sulfide : quinone reductase (SQR) in sediment environments. Based on the phylogenetic analysis, we classified the sqr sequences into six groups. PCR primers specific for each group were developed. We successfully amplified sqr-like gene sequences related to groups 1, 2 and 4 from diverse sediments including a marine sediment (SW), a tidal flat (TS), a river sediment (RS) and a lake sediment (FW). We recovered a total of 82 unique phylotypes (based on a 95 % amino acid sequence similarity cutoff) from 243 individual sqr-like gene sequences. Phylotype richness varied widely among the groups of sqr-like gene sequences (group 1.group 2.group 4) and sediments (SW.TS.RS.FW). Most of the sqr-like gene sequences were affiliated with the Proteobacteria clade and were distantly related to the reference sqr gene sequences from cultivated strains (less than~80 % amino acid sequence similarity). Unique sqr-like gene sequences were associated with individual sediment samples in groups 1 and 2. This molecular tool has also enabled us to detect sqr-like genes in a sulfuroxidizing enrichment from marine sediments. Collectively, our results support the presence of previously unrecognized sqr gene-containing micro-organisms that play important roles in the global biogeochemical cycle of sulfur. INTRODUCTIONSulfide, the most reduced form of inorganic sulfur, occurs in sediment environments, where it is generated from anaerobic sulfate-reducing bacteria (Detmers et al., 2001;Sorensen et al., 1981). Besides chemical oxidation, microorganisms are involved in the oxidation of sulfide at oxicanoxic interfaces; this reaction initiates the first step of the sulfur oxidation process (Cytryn et al., 2005;Jorgensen, 1982) and produces sulfate or sulfur as the major oxidation product (Friedrich, 1998;Ruepp et al., 2000;She et al., 2001;Theissen et al., 2003).The oxidation of sulfide to sulfate is mediated by membrane-bound electron-transport systems. Two main enzymic systems participating in the initial step have been intensively studied to understand the mechanism of sulfide oxidation. The electrons from sulfide enter the electrontransport chain either at the level of c-type cytochromes, via a sulfide : cytochrome c reductase (FCC) (Kusai & Yamanaka, 1973a, b, c; Lyric & Suzuki, 1970a, b, c), or at the level of quinone via a sulfide : quinone reductase (SQR) (Nubel et al., 2000;Schutz et al., 1997Schutz et al., , 1998Schutz et al., , 1999. FCC was suggested to play an essential role in sulfide oxidation in vivo, and found in a number of chemotrophic and phototrophic sulfide-oxidizing bacteria (Griesbeck et al., 2000;Schutz et al., 1999). However, it is not obligatory in sulfide oxidation since FCC does not occur in a variety of sulfide-oxidizing bacteria, and appears to be dispensable in the micro-organisms in which it is present (Brune, 1995). For example, disruption of the fcc gene in Chromatium vinosum did not have any signifi...

show abstract

“…Of course SoxF is probably not the only source of the sulfide dehydrogenase activity present since the C. tepidum genome contains genes encoding membrane-bound sulfide-quinone reductase (SQR). 42) Core TOMES has significant sulfide dehydrogenase activity, although the specific activity and the affinity for sulfide were lower than those of SoxF at pH 7.8 (Fig. 5, Table 2).…”

Section: Thiosulfatophilummentioning

confidence: 96%