Figure 2.

Relationship between Ace2p and Sep1. (A) Overexpression of ace2⁺ restores transcription in sep1Δ cells. RNA was extracted from wild-type (h123) or sep1Δ (A131) strains carrying pREP3X-ace2⁺ grown for 22 h in the absence of thiamine (ace2 OE). The wild-type strain carrying empty vector grown under the same conditions (first lane) was used to determine the endogenous transcript levels. After transfer to nitrocellulose membranes, RNA blots were sequentially hybridized with specific probes for eng1⁺, agn1⁺, adg1⁺, adg2⁺, adg3⁺, cfh4⁺, and ace2⁺, using his3⁺ as loading control. (B) Moderate ace2⁺ overexpression complements the cell separation defect of sep1Δ cells. Representative microscopic images of the sep1Δ mutant (top) or the sep1Δ mutant carrying pREP81X-ace2⁺ (middle) are shown. Quantitation of the percentage of septa in both cultures is shown in the bottom panel. Cells were stained with aniline blue and DAPI before counting. For each sample, 200 cells of were counted. (C) Model depicting transcriptional regulation during the last stages of the S. pombe cell cycle.