Cloning and sequencing of the URA5 gene from the yeast Yarrowia lipolytica.

The URA5 gene of Yarrowia lipolytica encoding the orotate phosphoribosyl transferase (OPRTase, EC2.4.2.10) was isolated by target integration in a mutant strain originally named ura2.21. The nucleotide sequence of the gene predicts a protein with high similarities with the OPRTases from Saccharomyces cerevisiae, Podospora anserina and Escherichia coli and to a lesser extent with that of Dictyostelium discoideum. The transcription start point has been mapped by primer extension analysis and indicates the existence of a long leader sequence in the corresponding mRNA. Northern-blot hybridization revealed the URA5 transcript to be approximately 0.94 kb. Deletion of the URA5 gene in Y. lipolytica produced a leaky phenotype similar to the one described for the ura5 mutation in S. cerevisiae. The URA5 gene of Y. lipolytica was able to complement functionally the ura5 mutation of S. cerevisiae.