Physiology and Genetics of Sulfur-oxidizing Bacteria

Friedrich, Cornelius G.

doi:10.1016/s0065-2911(08)60018-1

Cited by 200 publications

(152 citation statements)

References 205 publications

Supporting

Mentioning

152

Contrasting

Order By: Relevance

“…soxVW and soxXYZABCDEFGH (Friedrich et al, 2000;Mukhopadhyaya et al, 2000;Rother et al, 2001;AppiaAyme & Berks, 2002). A consensus mechanism allegedly governing the complete oxidation of thiosulfate, sulfite, sulfide and elemental sulfur has been proposed with a-proteobacteria as model systems involving a sulfuroxidizing multi-enzyme complex comprising the thiosulfate-induced periplasmic proteins SoxXA, SoxYZ, SoxB and SoxCD (Friedrich, 1998;Appia-Ayme et al, 2001). While the proteins SoxV and SoxW are believed to be involved in the biosynthesis or maintenance of the multienzyme complex system Appia-Ayme & Berks, 2002), the genes soxEFGH, though co-expressed with the sox structural genes in P. pantotrophus, might not be essential for sulfur oxidation by the aforesaid mechanism (Rother et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

The dimeric repressor SoxR binds cooperatively to the promoter(s) regulating expression of the sulfur oxidation (sox) operon of Pseudaminobacter salicylatoxidans KCT001

et al. 2007

View full text Add to dashboard Cite

Sulfur oxidation in Pseudaminobacter salicylatoxidans KCT001 is rendered by the combined action of several enzymes encoded by a thiosulfate-inducible sox operon. In this study it has been conclusively demonstrated by insertional mutagenesis that the regulatory gene of this operon is soxR, which encodes a DNA-binding protein belonging to the ArsR-SmtB family. SoxR was found to bind to two promoter-operator segments within the sox cluster, of which the one (wx) located between soxW and soxX controls the expression of sulfur-oxidation genes soxX through soxD while the other, a bi-directional element (sv) located between soxS and soxV, controls the expression of soxVW in one direction and the putative regulatory cluster soxSRT in the other. In the case of the wx promoter the repressor was found to bind in a cooperative manner to two distinct binding sites having different affinities, while in the case of the sv promoter binding occurred at a symmetric dimeric site and involved a higher degree of cooperativity. The high degree of cooperativity observed in the binding of SoxR to its target sites seemed to be due to the propensity of SoxR monomers to form dimers. The apparent dissociation constants of the SoxR-operator complexes were in the nanomolar range, indicating relatively strong interactions. It was demonstrated using a reporter system in Escherichia coli that this high-affinity binding of SoxR led to efficient repression in trans. Thus the role of SoxR as a repressor of the sox operon has not only been conclusively established but it has also been shown that this repression is brought about through cooperative interactions of SoxR with dimeric binding sites that occlude the operon promoters.

show abstract

Section: Introductionmentioning

confidence: 99%

The dimeric repressor SoxR binds cooperatively to the promoter(s) regulating expression of the sulfur oxidation (sox) operon of Pseudaminobacter salicylatoxidans KCT001

et al. 2007

View full text Add to dashboard Cite

show abstract

“…Sulphite oxidation can support chemolithotrophic and phototrophic growth in a diverse range of bacteria and archaea (Wood, 1988;Sorokin, 1995;Friedrich, 1998) and is known to occur either by direct oxidation, usually utilizing a molybdenum-containing sulphite : cytochrome c oxidoreductase (SOR) or by indirect, AMP-dependent oxidation via the intermediate adenylylsulphate (Wood, 1988;. In this study, we demonstrate the ability of the chemoheterotrophic pathogen C. jejuni to utilize sulphite and metabisulphite as respiratory electron donors, identify the proteins constituting the sulphite oxidase and elucidate the pathway for electron transport from sulphite to oxygen.…”

Section: Introductionmentioning

confidence: 99%

A sulphite respiration system in the chemoheterotrophic human pathogen Campylobacter jejuni

2005

View full text Add to dashboard Cite

The ability to use sulphite as a respiratory electron donor is usually associated with free-living chemolithotrophic sulphur-oxidizing bacteria. However, this paper shows that the chemoheterotrophic human pathogen Campylobacter jejuni has the ability to respire sulphite, with oxygen uptake rates of 23±8 and 28±15 nmol O2 min−1 (mg cell protein)−1 after the addition of 0·5 mM sodium sulphite or metabisulphite, respectively, to intact cells. The C. jejuni NCTC 11168 Cj0004c and Cj0005c genes encode a monohaem cytochrome c and molybdopterin oxidoreductase, respectively, homologous to the sulphite : cytochrome c oxidoreductase (SOR) of Starkeya novella. Western blots of C. jejuni periplasm probed with a SorA antibody demonstrated cross-reaction of a 45 kDa band, consistent with the size of Cj0005. The Cj0004c gene was inactivated by insertion of a kanamycin-resistance cassette. The resulting mutant showed wild-type rates of formate-dependent respiration but was unable to respire with sulphite or metabisulphite as electron donors. 2-Heptyl-4-hydroxyquinoline-N-oxide (HQNO), a cytochrome bc 1 complex inhibitor, did not affect sulphite respiration at concentrations up to 25 μM, whereas formate respiration (which occurs partly via a bc 1 dependent route) was inhibited 50 %, thus suggesting that electrons from sulphite enter the respiratory chain after the bc 1 complex at the level of cytochrome c. Periplasmic extracts of wild-type C. jejuni 11168 showed a symmetrical absorption peak at 552 nm after the addition of sulphite, demonstrating the reduction of cytochrome c. No cytochrome c reduction was observed after addition of sulphite to periplasmic extracts of the Cj0004c mutant. A fractionation study confirmed that the majority of the SOR activity is located in the periplasm in C. jejuni, and this activity was partially purified by ion-exchange chromatography. The presence of a sulphite respiration system in C. jejuni is another example of the surprising diversity of the electron-transport chain in this small-genome pathogen. Sulphite respiration may be of importance for survival in environmental microaerobic niches and some foods, and may also provide a detoxification mechanism for this normally growth-inhibitory compound.

show abstract

“…pantotrophus grows with thiosulfate exclusively under aerobic conditions and not anaerobically with nitrate as electron acceptor (Friedrich, 1998). The formation of proteins required for chemotrophic growth with thiosulfate is induced by thiosulfate.…”

Section: Introductionmentioning

confidence: 99%

“…1). The Sox proteins required for sulfur oxidation are expressed in the presence of thiosulfate in chemotrophic bacteria Kelly et al, 1997) as are the respective proteins in phototrophic purple bacteria, purple non-sulfur and green bacteria (reviewed by Friedrich, 1998). Apart from marginal physiological studies no information is available on the regulation of the proteins involved in sulfur oxidation at the molecular biological level, or on the mechanisms that lead to the formation of the Sox proteins in chemotrophic or phototrophic bacteria.…”

Section: Introductionmentioning

confidence: 99%

SoxRS-mediated regulation of chemotrophic sulfur oxidation in Paracoccus pantotrophus

et al. 2005

Self Cite

View full text Add to dashboard Cite

Paracoccus pantotrophus GB17 requires thiosulfate for induction of the sulfur-oxidizing (Sox) enzyme system. The soxRS genes are divergently oriented to the soxVWXYZA-H genes. soxR predicts a transcriptional regulator of the ArsR family and soxS a periplasmic thioredoxin. The homogenote mutant GBVS carrying a disruption of soxS by the V-kanamycin-resistance-encoding interposon expressed a low thiosulfate-oxidizing activity under heterotrophic and mixotrophic growth conditions. This activity was repressed by complementation with soxR, suggesting that SoxR acts as a repressor and SoxS is essential for full expression. Sequence analysis uncovered operator characteristics in the intergenic regions soxS-soxV and soxW-soxX. In each region a transcription start site was identified by primer extension analysis. Both regions were cloned into the vector pRI1 and transferred to P. pantotrophus. Strains harbouring pRI1 with soxS-soxV or soxW-soxX expressed the sox genes under heterotrophic conditions at a low rate, indicating repressor titration. Sequence analysis of SoxR suggested a helix-turn-helix (HTH) motif at position 87-108 and uncovered an invariant Cys-80 and a cysteine residue at the C-terminus. SoxR was overproduced in Escherichia coli with an N-terminal His 6 -tag and purified to near homogeneity. Electrophoretic gel mobility shift assays with SoxR retarded the soxS-soxV region as a single band while the soxW-soxX region revealed at least two protein-DNA complexes. These data demonstrated binding of SoxR to the relevant DNA. This is believed to be the first report of regulation of chemotrophic sulfur oxidation at the molecular level.

show abstract

Physiology and Genetics of Sulfur-oxidizing Bacteria

Cited by 200 publications

References 205 publications

The dimeric repressor SoxR binds cooperatively to the promoter(s) regulating expression of the sulfur oxidation (sox) operon of Pseudaminobacter salicylatoxidans KCT001

The dimeric repressor SoxR binds cooperatively to the promoter(s) regulating expression of the sulfur oxidation (sox) operon of Pseudaminobacter salicylatoxidans KCT001

A sulphite respiration system in the chemoheterotrophic human pathogen Campylobacter jejuni

SoxRS-mediated regulation of chemotrophic sulfur oxidation in Paracoccus pantotrophus

Contact Info

Product

Resources

About