Sulfur metabolism: Difference between revisions
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Sulfur reduction occurs in plants, fungi, and many bacteria.<ref name="metacyc">"[http://biocyc.org/META/NEW-IMAGE?type=PATHWAY&object=SO4ASSIM-PWY Pathway: sulfate reduction I (assimilatory)]." ''MetaCyc''.</ref> Sulfate can serve as an [[electron acceptor]] in [[anaerobic respiration]] and can also be reduced for the formation of [[organic compound]]s. [[Sulfate-reducing bacteria]] reduce sulfate and other oxidized sulfur compounds, such as sulfite, thiosulfate, and elemental sulfur, to [[sulfide]]. |
Sulfur reduction occurs in plants, fungi, and many bacteria.<ref name="metacyc">"[http://biocyc.org/META/NEW-IMAGE?type=PATHWAY&object=SO4ASSIM-PWY Pathway: sulfate reduction I (assimilatory)]." ''MetaCyc''.</ref> Sulfate can serve as an [[electron acceptor]] in [[anaerobic respiration]] and can also be reduced for the formation of [[organic compound]]s. [[Sulfate-reducing bacteria]] reduce sulfate and other oxidized sulfur compounds, such as sulfite, thiosulfate, and elemental sulfur, to [[sulfide]]. |
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=== Dissimilatory Sulfur Reduction === |
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Some microorganisms are capable of reducing sulfate and elemental sulfur for energy by coupling sulfur reduction with the oxidation of molecular hydrogen or organic compounds such as acetate. <ref name=":1">{{Citation |last=Rabus |first=Ralf |title=Dissimilatory Sulfate- and Sulfur-Reducing Prokaryotes |date=2006 |url=http://link.springer.com/10.1007/0-387-30742-7_22 |work=The Prokaryotes |pages=659–768 |editor-last=Dworkin |editor-first=Martin |place=New York, NY |publisher=Springer New York |language=en |doi=10.1007/0-387-30742-7_22 |isbn=978-0-387-25492-0 |access-date=2023-02-13 |last2=Hansen |first2=Theo A. |last3=Widdel |first3=Friedrich |editor2-last=Falkow |editor2-first=Stanley |editor3-last=Rosenberg |editor3-first=Eugene |editor4-last=Schleifer |editor4-first=Karl-Heinz}}</ref> These processes typically produce hydrogen sulfide as a byproduct, which can go on to serve as an electron donor in sulfur oxidation.<ref name=":1" /> Sulfate reduction by sulfate-reducing bacteria is dissimilatory; the purpose of reducing the sulfate is to produce energy, and the sulfide is excreted. [[Dissimilatory sulfate reduction]] use the enzymes [[Sulfate adenylyltransferase|ATP sulfurylase]], [[Adenylyl-sulfate reductase|APS reductase]], and [[sulfite reductase]].<ref>"[http://metacyc.org/META/new-image?type=PATHWAY&object=DISSULFRED-PWY Pathway: sulfate reduction IV (dissimilatory)]." ''MetaCyc''.</ref> |
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=== Assimilatory Sulfur Reduction === |
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| ⚫ | In assimilatory sulfate reduction the sulfate is assimilated, or incorporated into organic compounds. In some organisms (e.g., [[gut flora]], [[cyanobacteria]], and [[yeast]]),<ref>"[http://biocyc.org/META/NEW-IMAGE?type=PATHWAY&object=SULFMETII-PWY Pathway: sulfate reduction II (assimilatory)]." ''MetaCyc''.</ref> assimilatory sulfate reduction is a more complex process that makes use of the enzymes ATP sulfurylase, [[Adenylyl-sulfate kinase|APS kinase]], [[Phosphoadenylyl-sulfate reductase (thioredoxin)|PAPS reductase]], and sulfite reductase.<ref name="metacyc" /> |
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==Use by plants and animals== |
==Use by plants and animals== |
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Revision as of 02:12, 13 February 2023
Sulfur is metabolized by all organisms, from bacteria and archaea to plants and animals. Sulfur can have an oxidation state from -2 to +6 and is reduced or oxidized by a diverse range of organisms.[1] The element is present in proteins, sulfate esters of polysaccharides, steroids, phenols, and sulfur-containing coenzymes.[2]
Oxidation
Reduced sulfur compounds are oxidized by most organisms, including higher animals and higher plants.[2] Some organisms can conserve energy (i.e., produce ATP) from the oxidation of sulfur and it can serve as the sole energy source for some lithotrophic bacteria and archaea.[3] Sulfur oxidizers use enzymes such as Sulfide:quinone reductase, sulfur dioxygenase and sulfite oxidase to oxidize sulfur compounds to sulfate.
Sulfur Oxidizing Bacteria
Reduced sulfur compounds, such as hydrogen sulfide, elemental sulfur, sulfite, thiosulfate, and various polythionates (e.g., tetrathionate), are oxidized by chemotrophic, phototrophic, and mixotrophic bacteria for energy.[1]
Chemotrophic Sulfur Oxidizing Bacteria
In order to have sufficient redox potential, microorganisms that use sulfur as an electron donor often use oxygen or nitrate as terminal electron acceptors.[4] Members of the chemotrophic Acidithiobacillus genus are able to oxidize a vast range of reduced sulfur compounds, but are restricted to acidic environments.[5] Chemotrophs that can produce sugars through chemosynthesis make up the base of some food chains. Food chains have formed in the absence of sunlight around hydrothermal vents, which emit hydrogen sulfide and carbon dioxide.
Phototrophic Sulfur Oxidizing Bacteria
Some bacteria use light energy to couple sulfur oxidation to carbon dioxide (CO2) fixation for growth. These fall into two general groups: green sulfur bacteria (GSB) and purple sulfur bacteria (PSB).[6] However, some Cyanobacteria are also able to use hydrogen sulfide as an electron donor during anoxygenic photosynthesis.[7] All PSB are part of the class Gammaproteobacteria and are found in two families: Chromatiaceae and Ectothiorhodospiraceae. Typically, sulfur globules accumulate intracellularly in Chromatiaceae and extracellularly in Ectothiorhodospiraceae, which is one distinguishing feature between these two groups of PSB.[8] GSB are found within the family Chlorobiaceae generally oxidize sulfide or elemental sulfur, but some members are able to utilize thiosulfate.[9]
Sulfur Oxidizing Archaea
Chemosynthetic archaea use hydrogen sulfide as an energy source for carbon fixation, producing sugars. Acidianus ambivalens uses sulfur oxygenase reductase (SOR) to convert elemental sulfur to sulfate, thiosulfate, and hydrogen sulfide through a disproportionation reaction.[10]
Reduction
Sulfur reduction occurs in plants, fungi, and many bacteria.[11] Sulfate can serve as an electron acceptor in anaerobic respiration and can also be reduced for the formation of organic compounds. Sulfate-reducing bacteria reduce sulfate and other oxidized sulfur compounds, such as sulfite, thiosulfate, and elemental sulfur, to sulfide.
Dissimilatory Sulfur Reduction
Some microorganisms are capable of reducing sulfate and elemental sulfur for energy by coupling sulfur reduction with the oxidation of molecular hydrogen or organic compounds such as acetate. [12] These processes typically produce hydrogen sulfide as a byproduct, which can go on to serve as an electron donor in sulfur oxidation.[12] Sulfate reduction by sulfate-reducing bacteria is dissimilatory; the purpose of reducing the sulfate is to produce energy, and the sulfide is excreted. Dissimilatory sulfate reduction use the enzymes ATP sulfurylase, APS reductase, and sulfite reductase.[13]
Assimilatory Sulfur Reduction
In assimilatory sulfate reduction the sulfate is assimilated, or incorporated into organic compounds. In some organisms (e.g., gut flora, cyanobacteria, and yeast),[14] assimilatory sulfate reduction is a more complex process that makes use of the enzymes ATP sulfurylase, APS kinase, PAPS reductase, and sulfite reductase.[11]
Use by plants and animals
Plants take up sulfate in their roots and reduce it to sulfide (see sulfur assimilation). Plants are able to reduce APS directly to sulfite (using APS reductase) without phosphorylating APS to PAPS. From the sulfide they form the amino acids cysteine and methionine, sulfolipids, and other sulfur compounds. Animals obtain sulfur from cysteine and methionine in the protein that they consume.
Sulfur is the third most abundant mineral element in the body.[15] The amino acids cysteine and methionine are used by the body to make glutathione. Excess cysteine and methionine are oxidized to sulfate by sulfite oxidase, eliminated in the urine, or stored as glutathione (which can serve as a store for sulfur).[15] The lack of sulfite oxidase, known as sulfite oxidase deficiency, causes physical deformities, mental retardation, and death.
See also
References
- ^ a b Loka Bharathi, P. A. (2008-01-01), Fath, Brian (ed.), "Sulfur Cycle", Encyclopedia of Ecology (Second Edition), Oxford: Elsevier, pp. 192–199, doi:10.1016/b978-0-444-63768-0.00761-7, ISBN 978-0-444-64130-4, retrieved 2023-02-12
- ^ a b Schiff JA (1979). "Pathways of assimilatory sulphate reduction in plants and microorganisms". In CIBA Foundation Symposium (ed.). Sulphur in Biology. John Wiley & Sons. pp. 49–50. ISBN 9780470718230.
- ^ https://www.sciencedirect.com/science/article/pii/S0065291108600181?via%3Dihub
- ^ Wasmund, Kenneth; Mußmann, Marc; Loy, Alexander (August 2017). "The life sulfuric: microbial ecology of sulfur cycling in marine sediments: Microbial sulfur cycling in marine sediments". Environmental Microbiology Reports. 9 (4): 323–344. doi:10.1111/1758-2229.12538. PMC 5573963. PMID 28419734.
- ^ Pronk JT, Meulenberg R, Hazeu W, Bos P, Kuenen JG (1990). "Oxidation of reduced inorganic sulphur compounds by acidophilic thiobacilli" (PDF). FEMS Microbiology Letters. 75 (2–3): 293–306. doi:10.1111/j.1574-6968.1990.tb04103.x.
- ^ Microbial sulfur metabolism. Christiane Dahl, Cornelius G. Friedrich. Berlin: Springer. 2008. ISBN 978-3-540-72682-1. OCLC 213092503.
{{cite book}}: CS1 maint: others (link) - ^ Cohen, Yehuda; Jørgensen, Bo Barker; Revsbech, Niels Peter; Poplawski, Ricardo (1986). "Adaptation to Hydrogen Sulfide of Oxygenic and Anoxygenic Photosynthesis among Cyanobacteria". Applied and Environmental Microbiology. 51 (2): 398–407. doi:10.1128/aem.51.2.398-407.1986. ISSN 0099-2240. PMC 238881. PMID 16346996.
- ^ Frigaard, Niels-Ulrik; Dahl, Christiane (2008-01-01), Poole, Robert K. (ed.), "Sulfur Metabolism in Phototrophic Sulfur Bacteria", Advances in Microbial Physiology, vol. 54, Academic Press, pp. 103–200, doi:10.1016/s0065-2911(08)00002-7, retrieved 2023-02-12
- ^ Sakurai, Hidehiro; Ogawa, Takuro; Shiga, Michiko; Inoue, Kazuhito (2010-06-01). "Inorganic sulfur oxidizing system in green sulfur bacteria". Photosynthesis Research. 104 (2): 163–176. doi:10.1007/s11120-010-9531-2. ISSN 1573-5079.
- ^ Janosch, Claudia; Remonsellez, Francisco; Sand, Wolfgang; Vera, Mario (2015-10-21). "Sulfur Oxygenase Reductase (Sor) in the Moderately Thermoacidophilic Leaching Bacteria: Studies in Sulfobacillus thermosulfidooxidans and Acidithiobacillus caldus". Microorganisms. 3 (4): 707–724. doi:10.3390/microorganisms3040707. ISSN 2076-2607. PMC 5023260. PMID 27682113.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b "Pathway: sulfate reduction I (assimilatory)." MetaCyc.
- ^ a b Rabus, Ralf; Hansen, Theo A.; Widdel, Friedrich (2006), Dworkin, Martin; Falkow, Stanley; Rosenberg, Eugene; Schleifer, Karl-Heinz (eds.), "Dissimilatory Sulfate- and Sulfur-Reducing Prokaryotes", The Prokaryotes, New York, NY: Springer New York, pp. 659–768, doi:10.1007/0-387-30742-7_22, ISBN 978-0-387-25492-0, retrieved 2023-02-13
- ^ "Pathway: sulfate reduction IV (dissimilatory)." MetaCyc.
- ^ "Pathway: sulfate reduction II (assimilatory)." MetaCyc.
- ^ a b Nimni ME, Han B, Cordoba F (2007). "Are we getting enough sulfur in our diet?". Nutr Metab (Lond). 4 (1): 24. doi:10.1186/1743-7075-4-24. PMC 2198910. PMID 17986345.
{{cite journal}}: CS1 maint: unflagged free DOI (link)
External links
Media related to Sulfur metabolism at Wikimedia Commons
