Biotin synthase is a pyridoxal phosphate-dependent cysteine desulfurase.

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Ollagnier-De-Choudens S, Mulliez E, Hewitson KS, Fontecave M

Biotin synthase is a pyridoxal phosphate-dependent cysteine desulfurase.

Biochemistry. 2002 Jul 23;41(29):9145-52.

PubMed ID

12119030 [ View in PubMed

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Abstract

Biotin synthase (BioB) is an iron-sulfur dimeric enzyme which catalyzes the last step in biotin synthesis. The reaction consists of the introduction of a sulfur atom into dethiobiotin. It is shown here that BioB displays a significant cysteine desulfurase activity, providing it with the ability to mobilize sulfur from free cysteine. This activity is dependent on pyridoxal 5'-phosphate (PLP) and dithiothreitol and proceeds through a protein-bound persulfide. Like other cysteine desulfurases, BioB binds 1 equiv of PLP. By site-directed mutagenesis, two conserved cysteines, Cys97 and Cys128, are shown to be critical for cysteine desulfuration and are good candidates as the site for a persulfide. Since biotin synthase activity is greatly increased by PLP and cysteine, even though it does not exceed 1 nmol of biotin/nmol of monomer, it is proposed that cysteine desulfuration is intimately linked to biotin synthesis. New scenarios for sulfur insertion into dethiobiotin, in which cysteine persulfides play a key role, are discussed.

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Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Pyridoxal phosphate	Cysteine desulfurase, mitochondrial	Protein	Humans	Unknown	Cofactor	Details