Functional Domains of the Regulatory Factor PHO81 of Saccharomyces cerevisiae.

ABSTRACT

It is found that minor changes around the basic motif (88-160) and the acidic motif (771-810) of the PHO81 protein can lead to the constitutive expression of the acid phosphatase gene (PHO5), and the two motifs work cooperatively. The PHO81 protein has six ankyrin repeats, which are the recognition sites of PHO81 protein with the PHO80-PHO85 protein complex. It is found that the ankyrin repeats 1,2,4,5 and 6 are important for the PHO81 protein, but the deletion of Pro(509) and Leu(510) in ankyrin repeat 3 does not affect the PHO81 protein. We have found a candidate nucleoplasmin-like nuclear location sequence at 701-719 of the PHO81 protein and the deletion of the corresponding DNA fragment inactivates the PHO81 protein. However, when the conservative amino acids Arg701 and Lys702 are constituted by Ser and Gln, or Lys717 replaced by Asn, or Arg719 is turned to Ser, the function PHO81 protein is not affected.