Figure 4.
DNA replication at some early-firing origins in the arm region and at centromeres is repressed in rif1Δ. BrdU incorporation and BSs of Mcm4 and Rif1 were analyzed as described in the legend for Figure 3. (A) The 3700- to 3800-kb region of chromosome I containing the centromere. Rif1 binds specifically to the centromere core region, and DNA replication in this specific segment is repressed in rif1Δ. Black bars indicate the locations of the pericentromeric regions. (B) The 300- to 500-kb region on chromosome III. Most of the ori on chromosome III are early-firing and are repressed in rif1Δ. Rif1 does not bind to these repressed origins. (C) Replication efficiency was determined at the indicated locations by quantitative PCR as described in the legend for Figure 3. cen1 and ori3–333 (an early-firing origin) are indicated in A and B, respectively. ori3–1283 is another early-firing origin on chromosome III, and ars2004 is a well-characterized efficient early-firing ori. Replication efficiency of these origins decreased in rif1Δ. Error bars indicate the SD from three independent experiments.