Comments: |
The enzyme binds a [4Fe-4S] and a [2Fe-2S] cluster. In every reaction cycle, the enzyme consumes two molecules of AdoMet. The first reaction produces 5′-deoxyadenosine and 4,5-secobiotin. Reaction with another equivalent of AdoMet results in abstraction of the C-6 methylene pro-S hydrogen atom from 4,5-secobiotin, and the resulting carbon radical is quenched via formation of an intramolecular C-S bond, thus closing the biotin tetrahydrothiophene 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. |
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] |
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