FIG. 2.

Effect of the mutations M1 and M2 on Pho2 and Pho4 binding in vitro. DNase I footprinting was performed as described in Materials and Methods. The upper strand of an SfuI (−206)-BamHI (−542) fragment, derived from the wild-type or mutated promoter, was labeled at the SfuI site. Pho4 or Pho2 was added as indicated at the top. The regions protected in the wild-type promoter are indicated on the side. The locations of the M1 and M2 mutations (Fig. 1) within the Pho2 binding site are shown schematically underneath.