Reaction: dethiobiotin + sulfur-(sulfur carrier) + 2 S-adenosyl-L-methionine + 2 reduced [2Fe-2S] ferredoxin = biotin + (sulfur carrier) + 2 L-methionine + 2 5'-deoxyadenosine + 2 oxidized [2Fe-2S] ferredoxin
Glossary: biotin = 5[(3aS,4S,6aR)-2-oxohexahydro(4H-thieno[4,5-d]imidazol-4-yl)]pentanoate
4,5-secobiotin = 6-[(4R,5R)-2-oxo-5-(sulfanylmethyl)imidazolidin-4-yl]hexanoate = 9-mercaptodethiobiotin
Other name(s): dethiobiotin:sulfur sulfurtransferase
Systematic name: dethiobiotin:sulfur-(sulfur carrier) sulfurtransferase
Comments: The enzyme binds a [4Fe-4S] and a [2Fe-2S] cluster. In every reaction cycle, the enzyme consumes two molecules of AdoMet, each producing 5'-deoxyadenosine and a putative dethiobiotinyl carbon radical. Reaction with another equivalent of AdoMet results in abstraction of the C-6 methylene pro-S hydrogen atom from 9-mercaptodethiobiotin, and the resulting carbon radical is quenched via formation of an intramolecular C-S bond, thus closing the biotin thiophane ring. The sulfur donor is believed to be the [2Fe-2S] cluster, which is sacrificed in the process, so that in vitro the reaction is a single turnover. In vivo, the [2Fe-2S] cluster can be reassembled by the Isc or Suf iron-sulfur cluster assembly systems, to allow further catalysis.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 80146-93-6
References:
1. Trainor, D.A., Parry, R.J. and Gitterman, A. Biotin biosynthesis. 2. Stereochemistry of sulfur introduction at C-4 of dethiobiotin. J. Am. Chem. Soc. 102 (1980) 1467-1468.
2. Shiuan, D. and Campbell, A. Transcriptional regulation and gene arrangement of Escherichia coli, Citrobacter freundii and Salmonella typhimurium biotin operons. Gene 67 (1988) 203-211. [PMID: 2971595]
3. Zhang, S., Sanyal, I., Bulboaca, G.H., Rich, A. and Flint, D.H. The gene for biotin synthase from Saccharomyces cerevisiae: cloning, sequencing, and complementation of Escherichia coli strains lacking biotin synthase. Arch. Biochem. Biophys. 309 (1994) 29-35. [PMID: 8117110]
4. Ugulava, N.B., Gibney, B.R. and Jarrett, J.T. Biotin synthase contains two distinct iron-sulfur cluster binding sites: chemical and spectroelectrochemical analysis of iron-sulfur cluster interconversions. Biochemistry 40 (2001) 8343-8351. [PMID: 11444981]
5. Berkovitch, F., Nicolet, Y., Wan, J.T., Jarrett, J.T. and Drennan, C.L. Crystal structure of biotin synthase, an S-adenosylmethionine-dependent radical enzyme. Science 303 (2004) 76-79. [PMID: 14704425]
6. Lotierzo, M., Tse Sum Bui, B., Florentin, D., Escalettes, F. and Marquet, A. Biotin synthase mechanism: an overview. Biochem. Soc. Trans. 33 (2005) 820-823. [PMID: 16042606]
7. Taylor, A.M., Farrar, C.E. and Jarrett, J.T. 9-Mercaptodethiobiotin is formed as a competent catalytic intermediate by Escherichia coli biotin synthase. Biochemistry 47 (2008) 9309-9317. [PMID: 18690713]
8. Reyda, M.R., Fugate, C.J. and Jarrett, J.T. A complex between biotin synthase and the iron-sulfur cluster assembly chaperone HscA that enhances in vivo cluster assembly. Biochemistry 48 (2009) 10782-10792. [PMID: 19821612]