Reductive cleavage of S-adenosylmethionine by biotin synthase from Escherichia coli
Ollagnier-de Choudens, Sandrine, Sanakis, Yiannis, Hewitson, Kirsty S., Roach, Peter, Münck, Eckard and Fontecave, Marc (2002) Reductive cleavage of S-adenosylmethionine by biotin synthase from Escherichia coli. Journal of Biological Chemistry, 277, (16), 13449-13454. (doi:10.1074/jbc.M111324200).
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Biotin synthase (BioB) catalyzes the insertion of a sulfur atom between the C6 and C9 carbons of dethiobiotin. Reconstituted BioB from Escherichia coli contains a [4Fe-4S](2+/1+) cluster thought to be involved in the reduction and cleavage of S-adenosylmethionine (AdoMet), generating methionine and the reactive 5'-deoxyadenosyl radical responsible for dethiobiotin H-abstraction. Using EPR and Mössbauer spectroscopy as well as methionine quantitation we demonstrate that the reduced S = 1/2 [4Fe-4S](1+) cluster is indeed capable of injecting one electron into AdoMet, generating one equivalent of both methionine and S = 0 [4Fe-4S](2+) cluster. Dethiobiotin is not required for the reaction. Using site-directed mutagenesis we show also that, among the eight cysteines of BioB, only three (Cys-53, Cys-57, Cys-60) are essential for AdoMet reductive cleavage, suggesting that these cysteines are involved in chelation of the [4Fe-4S](2+/1+) cluster.
|Keywords:||iron-sulfur cluster, pyruvate formate-lyase, anaerobic ribonucleotide reductase, electron-paramagnetic-resonance, lysine 2,3-aminomutase, radical mechanisms, activating enzyme, single turnover, in-vitro, protein|
|Subjects:||Q Science > QD Chemistry
Q Science > QR Microbiology
|Divisions:||University Structure - Pre August 2011 > School of Chemistry
|Date Deposited:||22 Feb 2006|
|Last Modified:||01 Jun 2011 06:14|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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