Reduction of DsrC trisulfide, thereby linking cytoplasmic reduction of sulfite to energy conservation at membrane; reverse function in sulfur oxidation.
MAPTEDMRRNHMDYLKHERVETVRGGIRGSKYSLAGCIDCHASKDQSGNPLPVTDEGQFC
QKCHSYLAVQPACFQCHRTTPAEGGATLGAVDLNSMTYEQLDALSLMQWHPAVSKDVSNA
R123
| PMID | Title & Author | Abstract | Year | |
| 0 | 20726534 | DsrJ, an essential part of the DsrMKJOP transmembrane complex in the purple sulfur bacterium Allochromatium vinosum, is an unusual triheme cytochrome c.Fabian Grein , Sofia S Venceslau, Lilian Schneider, Peter Hildebrandt, Smilja Todorovic, Inês A C Pereira, Christiane Dah | The DsrMKJOP transmembrane complex has a most important function in dissimilatory sulfur metabolism, not only in many sulfur-oxidizing organisms but also in sulfate-reducing prokaryotes. Here, we focused on an individual component of this complex, the triheme cytochrome c DsrJ from the purple sulfur bacterium Allochromatium vinosum. In A. vinosum, the signal peptide of DsrJ is not cleaved off but serves as a membrane anchor. Sequence analysis suggested the presence of three heme c species with bis-His, His/Met, and possibly a very unusual His/Cys ligation. A. vinosum DsrJ produced as a recombinant protein in Escherichia coli indeed contained three hemes, and electron paramagnetic resonance (EPR) spectroscopy provided evidence of possible, but only partial, His/Cys heme ligation in one of the hemes. This heme shows heterogeneous coordination, with Met being another candidate ligand. Cysteine 46 was replaced with serine using site-directed mutagenesis, with the mutant protein showing a small decrease in the magnitude of the EPR signal attributed to His/Cys coordination, but identical UV-vis and RR spectra. The redox potentials of the hemes in the wild-type protein were determined to be -20, -200, and -220 mV and were found to be virtually identical in the mutant protein. However, in vivo the same ligand exchange led to a dramatically altered phenotype, highlighting the importance of Cys46. Our results suggest that Cys46 may be involved in catalytic sulfur chemistry rather than electron transfer. Additional in vivo experiments showed that DsrJ can be functionally replaced in A. vinosum by the homologous protein from the sulfate reducer Desulfovibrio vulgaris. | 2010 |
| 1 | 16388601 | Characterization of the Desulfovibrio desulfuricans ATCC 27774 DsrMKJOP complex--a membrane-bound redox complex involved in the sulfate respiratory pathway.Ricardo H Pires , Sofia S Venceslau, Francisco Morais, Miguel Teixeira, António V Xavier, Inês A C Pereira | Sulfate-reducing organisms use sulfate as an electron acceptor in an anaerobic respiratory process. Despite their ubiquitous occurrence, sulfate respiration is still poorly characterized. Genome analysis of sulfate-reducing organisms sequenced to date permitted the identification of only two strictly conserved membrane complexes. We report here the purification and characterization of one of these complexes, DsrMKJOP, from Desulfovibrio desulfuricans ATCC 27774. The complex has hemes of the c and b types and several iron-sulfur centers. The corresponding genes in the genome of Desulfovibrio vulgaris were analyzed. dsrM encodes an integral membrane cytochrome b; dsrK encodes a protein homologous to the HdrD subunit of heterodisulfide reductase; dsrJ encodes a triheme periplasmic cytochrome c; dsrO encodes a periplasmic FeS protein; and dsrM encodes another integral membrane protein. Sequence analysis and EPR studies indicate that DsrJ belongs to a novel family of multiheme cytochromes c and that its three hemes have different types of coordination, one bis-His, one His/Met, and the third a very unusual His/Cys coordination. The His/Cys-coordinated heme is only partially reduced by dithionite. About 40% of the hemes are reduced by menadiol, but no reduction is observed upon treatment with H2 and hydrogenase, irrespective of the presence of cytochrome c3. The aerobically isolated Dsr complex displays an EPR signal with similar characteristics to the catalytic [4Fe-4S]3+ species observed in heterodisulfide reductases. Further five different [4Fe-4S](2+/1+) centers are observed during a redox titration followed by EPR. The role of the DsrMKJOP complex in the sulfate respiratory chain of Desulfovibrio spp. is discussed. | 2006 |
| 2 | 15687204 | Novel genes of the dsr gene cluster and evidence for close interaction of Dsr proteins during sulfur oxidation in the phototrophic sulfur bacterium Allochromatium vinosum.Christiane Dahl , Sabine Engels, Andrea S Pott-Sperling, Andrea Schulte, Johannes Sander, Yvonne Lübbe, Oliver Deuster, Daniel C Brune | Seven new genes designated dsrLJOPNSR were identified immediately downstream of dsrABEFHCMK, completing the dsr gene cluster of the phototrophic sulfur bacterium Allochromatium vinosum D (DSM 180(T)). Interposon mutagenesis proved an essential role of the encoded proteins for the oxidation of intracellular sulfur, an obligate intermediate during the oxidation of sulfide and thiosulfate. While dsrR and dsrS encode cytoplasmic proteins of unknown function, the other genes encode a predicted NADPH:acceptor oxidoreductase (DsrL), a triheme c-type cytochrome (DsrJ), a periplasmic iron-sulfur protein (DsrO), and an integral membrane protein (DsrP). DsrN resembles cobyrinic acid a,c-diamide synthases and is probably involved in the biosynthesis of siro(heme)amide, the prosthetic group of the dsrAB-encoded sulfite reductase. The presence of most predicted Dsr proteins in A. vinosum was verified by Western blot analysis. With the exception of the constitutively present DsrC, the formation of Dsr gene products was greatly enhanced by sulfide. DsrEFH were purified from the soluble fraction and constitute a soluble alpha(2)beta(2)gamma(2)-structured 75-kDa holoprotein. DsrKJO were purified from membranes pointing at the presence of a transmembrane electron-transporting complex consisting of DsrKMJOP. In accordance with the suggestion that related complexes from dissimilatory sulfate reducers transfer electrons to sulfite reductase, the A. vinosum Dsr complex is copurified with sulfite reductase, DsrEFH, and DsrC. We therefore now have an ideal and unique possibility to study the interaction of sulfite reductase with other proteins and to clarify the long-standing problem of electron transport from and to sulfite reductase, not only in phototrophic bacteria but also in sulfate-reducing prokaryotes. | 2005 |
| 3 | DOI: 10.1007 | Importance of the DsrMKJOP complex for sulfur oxidation in Allochromatium vinosum and phylogenetic analysis of related complexes in other prokaryotes.Sander, J (Sander, Johannes); Engels-Schwarzlose, S (Engels-Schwarzlose, Sabine); Dahl, C (Dahl, Christiane) | In the phototrophic sulfur bacterium Allochromatium vinosum, sulfur of oxidation state zero stored in intracellular sulfur globules is an obligate intermediate during the oxidation of sulfide and thiosulfate. The proteins encoded in the dissimilatory sulfite reductase (dsr) locus are essential for the oxidation of the stored sulfur. DsrMKJOP form a membrane-spanning complex proposed to accept electrons from or to deliver electrons to cytoplasmic sulfur-oxidizing proteins. In frame deletion mutagenesis showed that each individual of the complex-encoding genes is an absolute requirement for the oxidation of the stored sulfur in Alc. vinosum. Complementation of the Delta dsrJ mutant using the conjugative broad host range plasmid pBBR1-MCS2 and the dsr promoter was successful. The importance of the DsrMKJOP complex is underlined by the fact that the respective genes occur in all currently sequenced genomes of sulfur-forming bacteria such as Thiobacillus denitrificans and Chlorobaculum tepidum. Furthermore, closely related genes are present in the genomes of sulfate- and sulfite-reducing prokaryotes. A phylogenetic analysis showed that most dsr genes from sulfide oxidizers are clearly separated of those from sulfate reducers. Surprisingly, the dsrMKJOP genes of the Chlorobiaceae all cluster together with those of the sulfate/sulfite-reducing prokaryotes, indicating a lateral gene transfer at the base of the Chlorobiaceae. | 2006 |
Grein, F., Pereira, I.A., and Dahl, C. (2010) Biochemical characterization of individual components of the Allochromatium vinosum DsrMKJOP transmembrane complex aids understanding of complex function in vivo. J Bacteriol 192: 6369–6377.