Figure 4.

Characterization of Cdc46p chromatin binding. (a) Cdc46p chromatin binding is insensitive to low salt concentrations. Supernatant and chromatin fractions from the Cdc46p tagged strain blocked in G₁ with α factor were prepared as above and divided into aliquots. One aliquot (−NaCl, lanes 2 and 3) was untreated. Another was treated with 0.25M NaCl before chromatin isolation. (b) Cdc46p chromatin binding is lost after DNase1 treatment. Supernatant and chromatin fractions from the Cdc46p tagged strain blocked in G₁ with α factor were prepared as above in 0.25 M NaCl and divided into aliquots. One aliquot of this extract was untreated (−DNase1), whereas the other (+DNase1) was treated with 3 Kunitz units of DNase1 before chromatin isolation. (c) Cdc46p chromatin binding is lost in a cdc47 mutant. Chromatin fractions were prepared as described above for either a wild-type (wt) or congenic cdc47–1 mutant strain (see Materials and Methods) from cells first blocked with α factor at 25°C and then shifted to 37°C for 1.5 h.