Characterization of the biotin biosynthesis pathway in Saccharomyces cerevisiae and evidence for a cluster containing BI05, a novel gene involved in vitamer uptake

An engineered mutant of Saccharomyces cerevisiae affected in biotin biosynt hesis has been isolated. This mutant allowed the characterization of a bio cluster (BIO3-4-5). We demonstrate that BIO3 (YNR058w) and BIO4 (YNR057c) e ncode, respectively, a 7,8-diaminopelargonic acid aminotransferase and a de thiobiotin synthase, involved in the biotin biosynthesis pathway. A novel g ene, BIO5 (YNR056c), is present immediately downstream from BIO4. This gene encodes Bio5p, a protein with 11 putative transmembrane regions. Uptake ex periments performed with labeled 7-keto 8-aminopelargonic acid indicate tha t Bio5p is responsible for transport into the cell of 7-keto 8-aminopelargo nic acid. (C) 1999 Elsevier Science B.V. All rights reserved.