PHO4 and PHO2 Protein Interact with Upstream Sequence of PHO81 Gene.

ABSTRACT

PHO4 and PHO2 protein were overexpressed in E. coli and purified respectively. The gel retardation assays showed that PHO4 and PHO2 protein could bind to -401 -289 bp sequence of PHO81 gene promoter respectively. The assays of the mutant PHO2 proteins where the Ser-230 was changed into Asp (GST-2SD) or Ala (GST-2SA) showed the binding patterns were the same as the intact PHO2 protein. Footprinting results located the PHO4 binding site at the 354 -333 bp sequence of PHO81 gene PHO2 binding site at the -341 -334 bp. Therefore the region (-401 -289 bp) contains the upstream activation sequence (UAS) of PHO81 gene and PHO4 protein cooperates with PHO2 in acting on the upstream sequence of PHO81 gene and both of them regulate the expression of PHO81 gene.