Saccharomyces cerevisiae starts biotin biosynthesis from 8-amino-7-oxononanoate, which it can import from the environment by the transporter encoded by the BIO5 gene. Once 8-amino-7-oxononanoate reacts with the common methyl-group donor S-adenosyl-L-methionine as an amino-group donor, a reaction catalyzed by the BIO3-encoded 7,8-diamino-pelargonic acid aminotransferase resulting in the release of 7,8-diaminopelargonate, is the target of a unique carboxylase, the BIO4-encoded dethiobiotin synthetase. This enzymee catalyzes the first ring closure by a carboxylation reaction that does not require biotin as a prosthetic group, forming dethiobiotin. The last step in the pathway is catalyzed by biotin synthase, encoded by BIO2. This enzyme inserts a sulfur atom between C6 and C9 of dethiobiotin in a S-adenosyl-L-methionine-dependent reaction resulting in the release of biotin.

Biotin Biosynthesis References