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GC-Rich DNA Elements Enable Replication Origin Activity in the Methylotrophic Yeast Pichia pastoris

Figure 4

Replication timing of the P. pastoris genome.

(A) Genomic DNA from G1 and S phase cells was sheared and sequenced. Normalized S/G1 DNA copy ratios (in 1 kbp windows) were smoothed and plotted against chromosomal coordinates. Peaks correspond to positions of replication initiation. The profile of chromosome 4 is shown (all chromosomes are shown in Figure S6) with ARS locations indicated by open (AT-ARSs) and shaded (GC-ARSs) circles. Un-smoothed ratio data for one of the replicates is shown are grey. Coordinates of replication timing peaks are indicated by dashed vertical lines. (B) The distributions of smoothed S/G1 ratio data. The distribution of all ratios (“Genome”) is shown adjacent to the distribution of values at bins containing midpoints of GC-ACSs (“GC”) or AT-ARSs (“AT”). Values for ARSs that have no other ARSs within 40 kb in both directions are shown on the right (“isolated”). (C) The complete genomic ratio distribution is shown relative to distributions after removal of data within 60 kb ranges centered on AT-ARSs (“AT”), GC-ARSs (“GC”), or all ARSs (“all ARS”). (D) For each ARS, the distance to the nearest replication peak was calculated. The ARS-peak distances are shown as distributions separately for GC-ARSs (blue) and AT-ARSs (orange). Peak distances from simulated random sets of loci are shown in grey.

Figure 4