THE P-OLE1 GENE OF PICHIA-ANGUSTA ENCODES A DELTA-9-FATTY ACID DESATURASE AND COMPLEMENTS THE OLE1 MUTATION OF SACCHAROMYCES-CEREVISIAE

Three PCR-amplified DNA fragments hybridizing with the OLE1 gene encod ing Delta 9-fatty acid desaturase of Saccharomyces cerevisiae were obt ained using, respectively, genomic DNAs of one strain each of Kluyvero myces thermotolerans, Pichia angusta and Yarrowia lipolytica as templa tes. A gene designated P-OLE1 was cloned from the above fragment of P. angusta and sequenced. An open reading frame of P-OLE1 encodes a 49.6 -kDa protein consisting of 451 amino acid residues, which shows high i dentity (62%) and similarity (89%) to that deduced from the OLE1 nucle otide sequence. Expression of P-OLE1 driven by the S. cerevisiae GAP p romoter or its own promoter complemented the ole1 mutation of S. cerev isiae. Transcription of P-OLE1 in the native host was suggested to be partially repressed by oleic acid in the medium, as was that of OLEI i n S. cerevisiae and a similar gene in Y. lipolytica, but that of a sim ilar gene in K. thermotolerans was not.