Cloning and functional verification of the Candida milleri HIS3 gene encoding imidazoleglycerol phosphate dehydratase

The entire nucleotide sequence of the HIS3 gene encoding imidazoleglycerol phosphate dehydratase (IGPD) in yeast Candida milleri CBS 8195 was determined. Sequence analysis revealed an open-reading frame of C. milleri HIS3 that spans 678 bp, encodes 226 amino acids, and shares 80.5% amino acid identity to Torulaspora delbrueckii IGPD, followed by that to Saccharomyces cerevisiae (79.6%). The cloned HIS3 gene complemented a his3 mutation in S. cerevisiae, suggesting that it encodes a functional IGPD in C. milleri CBS 8195. A new auxotrophic marker is now available for acid-tolerant yeast C. milleri.