The BioBFCD operon in E. coli contains four genes involved in the biosynthesis of biotin, a molecule important for various metabolic functions in the cell. The operon can be inactivated by the ginding of bifunctional protein BirA when it interacts with the biotin carboxyl carrier protein of acetyl-CoA carboxylase (AccB). This complex forms when AccB is in high concentrations, due to high levels of biotin already in the cell. The first gene in the operon, bioB, encodes biotin synthase, and enzyme that catalyzes conversion of dethiobiotin into biotin. The second gene, bioF, encodes 8-amino-7-oxononanoate synthase. This protein is an enzyme that condenses pimeloyl-[ACP] and L-alanine to form 8-amino-7-oxononanoate. This is later used in biotin biosynthesis. The third gene, bioC, encodes malonyl-[ACP] methyltransferase, a protein that methylates malonyl-thioester to its ester form as a part of biotin biosynthesis. The final gene, bioD, encodes dethiobiotin synthetase. This enzyme forms dethiobiotin, the direct precursor to biotin, by adding a carbon dioxide molecule into 7,8-diaminononanoate, which ends up forming a ring structure. Dethiobiotin is then acted upon by biotin synthase, forming biotin.

Operon: Biotin Biosynthesis References