Biology:Carbonyl sulfide hydrolase

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Short description: Hydrolase enzyme
Carbonyl sulfide hydrolase (COSase)
Identifiers
EC number3.13.1.7
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
Carbonyl Sulfide Hydrolase (COSase)
Identifiers
SymbolCarbonyl Sulfide Hydrolase (COSase)
PfamPF00484
InterProIPR036874 IPR001765, IPR036874
SMARTSM00947

Carbonyl sulfide hydrolase (EC 3.13.1.7; abbreviated as COSase) is an enzyme that degrades carbonyl sulfide (COS) to hydrogen sulfide (H2S) and carbon dioxide (CO2). Isolated from Thiobacillus thioparus bacterium, the potential of COSase would reduce the high global warming effect of COS and change the ozone chemistry, because COS is the source of sulfur in the troposphere.[1][2][3]

Etymology

Being that it is a hydrolase, which is an enzyme that uses water to break chemical bonds, the name suggests that within the mechanism are water molecules that are involved in disseminating molecules within the reaction. The very name when broken down means that it is an enzyme that breaks down carbonyl sulfide.

History

COSase was isolated, characterized and structure was determined from Thiobacillus thioparus bacterium. In search for a chemical method to break down COS more efficiently than the biologically established methods that employ the soil environment for degradation enzymes. These enzymes are carbonic anhydrase, carbonic disulfide hydrolase, nitrogenase, carbon monoxide, and RuBisCO.[4][5][6][7][8][9][10][11][12] The enzymes listed are limited in their use due to specificities and optimal environments, which is why chemical development of an enzyme unique to catalyzing the degradation of COS is researched. - Thiobacillus thioparus is a bacterium found both in soil and freshwater and is known for its sulfur-oxidizing properties. The strain used to create COSase is THI11, which was originally isolated as a thiocyanate degrading microorganism.[13] The enzyme was found by putting the extract of T. thioparus strain THI115 through column chromatography to purify it and ICP-MS to deduce the structure.[1]

Structure

Using sodium dodecyl sulfate–polyacrylamide gel electrophoresis, a subunit molecular mass of 27 kDa was found.[1] After testing for expression in E. coli the true molecular mass of ~94 kDa was found by SEC-MALS.[1] ICP-MS shows that there is one zinc ion per sub unit.[1] 35 amino acid sequence found on the N-terminal: MEKSNTDALLENNRLYAGGQATHRPGHPGMQPIQP.[1] There are five strands (β1−β5) that make up β-sheet core and four α-helices (α1, α2, α3, and α6) in its flank, with two additional helices (α4 and α5) that protrude from its core. They arrange in homodimer pairs to form ten-stranded β-sheets.[1] Between two subunits of a homodimer is the catalytic site. Cys44, His97, Cys 100, and a water molecule coordinate with a zinc ion, with a thiocyanate molecule in the catalytic site pocket.[1]

Function

COSase is responsible for the degradation of COS to H2S and CO2 in the second step of SCN− assimilation. It hydrolyzes COS with a certain specificity over a wide range of concentrations both in vivo and in vitro.[1]

Mechanism

Thiocyanate hydrolase (SCNase) found in THI115 initiates enzymatic formation of thiocyanate (SCN−). SCNase hydrolyzes SCN− to ammonia and COS. The COS that results from the hydrolysis is metabolized to form hydrogen sulfide (H2S) which is oxidized to sulfate to produce energy.[14][15][16][17][18]

Hydroxide and zinc io ns perform a nucleophilic attack on the carbon in the COS molecule, which creates an intermediate with zinc bound to hydroxide oxygen and sulfur of the COS molecule. Oxygen is then released from zinc and forms CO2. Water from the solvent interacts with the su lfur-zinc ion and regenerates the active site and releases H2S.[1]

Carbonyl sulfide hydrolase inhibitor

COSase is weakly inhibited by SCN−.[1]

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 "Carbonyl sulfide hydrolase from Thiobacillus thioparus strain THI115 is one of the β-carbonic anhydrase family enzymes". Journal of the American Chemical Society 135 (10): 3818–25. March 2013. doi:10.1021/ja307735e. PMID 23406161. 
  2. ↑ "A reanalysis of carbonyl sulfide as a source of stratospheric background sulfur aerosol". Journal of Geophysical Research 100 (D5): 8993. 1995. doi:10.1029/95JD00275. Bibcode: 1995JGR...100.8993C. 
  3. ↑ "Atmospheric Aerosols: Biogeochemical Sources and Role in Atmospheric Chemistry". Science 276 (5315): 1052–1058. 16 May 1997. doi:10.1126/science.276.5315.1052. 
  4. ↑ "Carbonic anhydrases: novel therapeutic applications for inhibitors and activators". Nature Reviews. Drug Discovery 7 (2): 168–81. February 2008. doi:10.1038/nrd2467. PMID 18167490. 
  5. ↑ "Carbonyl sulfide and carbon dioxide as new substrates, and carbon disulfide as a new inhibitor, of nitrogenase". Biochemistry 34 (16): 5382–9. April 1995. doi:10.1021/bi00016a009. PMID 7727396. 
  6. ↑ "Consumption of carbonyl sulphide (COS) by higher plant carbonic anhydrase (CA)". Atmospheric Environment 30 (18): 3151–3156. September 1996. doi:10.1016/1352-2310(96)00026-X. Bibcode: 1996AtmEn..30.3151P. 
  7. ↑ "Use of Carbon Oxysulfide, a Structural Analog of CO(2), to Study Active CO(2) Transport in the Cyanobacterium Synechococcus UTEX 625". Plant Physiology 90 (3): 1221–31. July 1989. doi:10.1104/pp.90.3.1221. PMID 16666875. 
  8. ↑ "Carbonyl sulfide: an alternate substrate for but not an activator of ribulose-1,5-bisphosphate carboxylase". The Journal of Biological Chemistry 264 (5): 2764–72. February 1989. doi:10.1016/S0021-9258(19)81679-4. PMID 2492523. 
  9. ↑ "Carbonic anhydrase metabolism is a key factor in the toxicity of CO2 and COS but not CS2 toward the flour beetle Tribolium castaneum [Coleoptera: Tenebrionidae]". Comparative Biochemistry and Physiology. Toxicology & Pharmacology 140 (1): 139–47. January 2005. doi:10.1016/j.cca.2005.01.012. PMID 15792633. 
  10. ↑ "Reactivity of carbon monoxide dehydrogenase from Rhodospirillum rubrum with carbon dioxide, carbonyl sulfide, and carbon disulfide". Biochemistry 34 (16): 5372–8. April 1995. doi:10.1021/bi00016a008. PMID 7727395. 
  11. ↑ "Hepatic carbonyl sulfide metabolism". Biochemical and Biophysical Research Communications 90 (3): 993–9. October 1979. doi:10.1016/0006-291X(79)91925-9. PMID 116662. 
  12. ↑ "Multiple binding modes of inhibitors to carbonic anhydrases: how to design specific drugs targeting 15 different isoforms?". Chemical Reviews 112 (8): 4421–68. August 2012. doi:10.1021/cr200176r. PMID 22607219. 
  13. ↑ "A thiocyanate hydrolase of Thiobacillus thioparus. A novel enzyme catalyzing the formation of carbonyl sulfide from thiocyanate". The Journal of Biological Chemistry 267 (13): 9170–5. May 1992. doi:10.1016/S0021-9258(19)50404-5. PMID 1577754. 
  14. ↑ "18O and OCS exchange". Soil Biology & Biochemistry 115: 371–382. December 2017. doi:10.1016/j.soilbio.2017.09.009. PMID 29200510. 
  15. ↑ "T Using Transcriptomics". mSystems 2 (6): mSystems.00102–17, e00102–17. 26 December 2017. doi:10.1128/mSystems.00102-17. PMID 29285524. 
  16. ↑ "Soil fluxes of carbonyl sulfide (COS), carbon monoxide, and carbon dioxide in a boreal forest in southern Finland". Atmospheric Chemistry and Physics 18 (2): 1363–1378. 1 February 2018. doi:10.5194/acp-18-1363-2018. Bibcode: 2018ACP....18.1363S. 
  17. ↑ "Stomatal control of leaf fluxes of carbonyl sulfide and CO<sub>2</sub> in a <i>Typha</i> freshwater marsh". Biogeosciences 15 (11): 3277–3291. 4 June 2018. doi:10.5194/bg-15-3277-2018. Bibcode: 2018BGeo...15.3277S. 
  18. ↑ "Mechanism of activity enhancement of the Ni based hydrotalcite-derived materials in carbonyl sulfide removal". Materials Chemistry and Physics 205: 35–43. 1 February 2018. doi:10.1016/j.matchemphys.2017.11.002. 

Further reading



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