This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Degradation/Utilization/Assimilation → Inorganic Nutrients Metabolism → Sulfur Compounds Metabolism → Thiosulfate Disproportionation|
The inorganic sulfur compound thiosulfate contains two sulfur atoms: a sulfone-sulfur (oxidation state +V), and a sulfane-sulfur (oxidation state -I). At low pH thiosulfate decomposes spontaneously to sulfite and elemental sulfur [Hashwa72]. At neutral pH the compound is relatively stable, but several types of bacteria can catalyze its disproportionation in a process in which thiosulfate serves as both an electron donor and an electron acceptor.
Several types of enzymes have been described that are able to catalyze the disproportionation of thiosulfate. These enzymes have been differentiated based on the nature of the electron donor: some enzymes require thiols for this purpose, others utilize organic electron donors such as pyruvate, as well as molecular hydrogen in the presence of a hydrogenase, and some enzymes have only been active in vitro when coupled to cyanide. These three classes of enzymes are described in the pathways thiosulfate disproportionation I (thiol-dependent), thiosulfate disproportionation II (non thiol-dependent) and thiosulfate disproportionation III (rhodanese), respectively.
About This Pathway
Thiosulfate sulfurtransferase is more often referred to by the name rhodanese, from the German word for thiocyanate, "rhodanid". The enzyme catalyzes the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. The original description of rhodanese, purified from bovine mitochondria, used thiosulfate and cyanide for this purpose. Rhodanese is a widespread enzyme, and has been detected in many major phyla, both prokaryotic and eukaryotic [Westley83]. Despite its ubiquity, the physiological role of rhodanese has not yet been established unambiguously. It has been suggested that rhodanese is involved in detoxification of cyanide in both mammals [Westley88, Nandi00] and bacteria [Cipollone08]. It has also been proposed that rhodanese, using the dithiol dihydrolipoate as the sulfur acceptor, may act as a sulfur insertase involved in the formation of prosthetic groups in iron-sulfur proteins, such as ferredoxin [Pagani84, Bonomi85].
Rhodanese performs the reaction by a double displacement formal mechanism. The crystal structure of rhodanese from Azotobacter vinelandii has been determined at 1.8 Å, and the study revealed that the active form of the enzyme is a persulfide, where a sulfur is attached to the active cysteine residue [Bordo00]. Unlike the enzyme thiosulfate—thiol sulfurtransferase, which catalyzes a similar reaction in which thiosulfate is disproportionated into sulfite and hydrogen sulfide, monothiols such as glutathione are poor substrates for rhodanese [Villarejo63, Volini66, Ray00].
The distinction between thiosulfate reductase and rhodanese is not always straight forward. For example, Aird et al purified an enzyme from Acinetobacter calcoaceticus that could catalyze either reaction under different conditions [Aird87].
Unification Links: EcoCyc:PWY-5350
Bordo00: Bordo D, Deriu D, Colnaghi R, Carpen A, Pagani S, Bolognesi M (2000). "The crystal structure of a sulfurtransferase from Azotobacter vinelandii highlights the evolutionary relationship between the rhodanese and phosphatase enzyme families." J Mol Biol 298(4);691-704. PMID: 10788330
Cipollone08: Cipollone R, Ascenzi P, Tomao P, Imperi F, Visca P (2008). "Enzymatic detoxification of cyanide: clues from Pseudomonas aeruginosa Rhodanese." J Mol Microbiol Biotechnol 15(2-3);199-211. PMID: 18685272
Ray00: Ray WK, Zeng G, Potters MB, Mansuri AM, Larson TJ (2000). "Characterization of a 12-kilodalton rhodanese encoded by glpE of Escherichia coli and its interaction with thioredoxin." J Bacteriol 2000;182(8);2277-84. PMID: 10735872
Bordo00a: Bordo D, Larson TJ, Donahue JL, Spallarossa A, Bolognesi M (2000). "Crystals of GlpE, a 12 kDa sulfurtransferase from escherichia coli, display 1.06 A resolution diffraction: a preliminary report." Acta Crystallogr D Biol Crystallogr 56(Pt 12);1691-3. PMID: 11092948
Bordo01: Bordo D, Forlani F, Spallarossa A, Colnaghi R, Carpen A, Bolognesi M, Pagani S (2001). "A persulfurated cysteine promotes active site reactivity in Azotobacter vinelandii Rhodanese." Biol Chem 382(8);1245-52. PMID: 11592406
Cereda09: Cereda A, Carpen A, Picariello G, Tedeschi G, Pagani S (2009). "The lack of rhodanese RhdA affects the sensitivity of Azotobacter vinelandii to oxidative events." Biochem J 418(1);135-43. PMID: 18925874
Cheng08: Cheng H, Donahue JL, Battle SE, Ray WK, Larson TJ (2008). "Biochemical and Genetic Characterization of PspE and GlpE, Two Single-domain Sulfurtransferases of Escherichia coli." Open Microbiol J 2;18-28. PMID: 19088907
Choi91: Choi YL, Kawase S, Kawamukai M, Sakai H, Komano T (1991). "Regulation of glpD and glpE gene expression by a cyclic AMP-cAMP receptor protein (cAMP-CRP) complex in Escherichia coli." Biochim Biophys Acta 1088(1);31-5. PMID: 1846566
Colnaghi01: Colnaghi R, Cassinelli G, Drummond M, Forlani F, Pagani S (2001). "Properties of the Escherichia coli rhodanese-like protein SseA: contribution of the active-site residue Ser240 to sulfur donor recognition." FEBS Lett 500(3);153-6. PMID: 11445076
Colnaghi96: Colnaghi R, Pagani S, Kennedy C, Drummond M (1996). "Cloning, sequence analysis and overexpression of the rhodanese gene of Azotobacter vinelandii." Eur J Biochem 236(1);240-8. PMID: 8617271
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Eichmann14: Eichmann C, Tzitzilonis C, Bordignon E, Maslennikov I, Choe S, Riek R (2014). "Solution NMR Structure and Functional Analysis of the Integral Membrane Protein YgaP from Escherichia coli." J Biol Chem 289(34);23482-503. PMID: 24958726
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