[Studies on the cloning, expression and function of the yeast PHO 80 gene]

Through in situ hybridization, a 4.2 kb Pst I-BamH I fragment was obtained from S. cerevisiae gene library. The cloned fragment contained 1100 bp upstream sequence and 879 bp coding sequence of the PHO80 gene. Coding region of PHO80 gene was substituted with URA3 gene and used as donor to transform YPH499 to URA3. A pho80 mutant resulted from deletion of the chromosomal counterpart in PHO80 was obtained. In vivo functional study of the PHO80 gene indicated that PHO80 was a negative regulator in the Pi-repressible acid phosphatase system including the structural genes PHO5 and PHO11 and the regulatory gene PHO81, whereas the expression of PHO4 or PHO85 was independent of PHO80. The coding region of PHO80 was fused in frame with LacZ and beta-galactosidase activities in various cells was determined. The results Showed that the PHO80 gene was expressed at a low level and suppressed by itself and PHO85.