FIG. 1.

NRSF(1-600) represses GAL1-HIS3 transcription in yeast in a SIN3-dependent manner. (a) Fragments of REST/NRSF used in this study. Inset: yeast reporter plasmid containing three RE1/NRSEs and a single consensus gal4 binding site upstream of GAL1, driving either HIS3 or lacZ. (b) Yeast strain FM242 bearing the reporter pBM2389(RE1)₃UAS and expressing the designated REST/NRSF fragments was streaked onto synthetic dropout plates containing 2% galactose–2% raffinose, lacking histidine, with the stated concentrations of 3-AT and incubated at 30°C for 3 days. (c) Wild-type and sin3⁻ (yA1) yeasts expressing the HZ4 fragment of REST/NRSF [NRSF(1-600)] or the DNA binding domain [NRSF(142-445)] or containing empty expression vector were assayed for histidine autotrophy as in Fig. 1b (see Materials and Methods). Synthetic dropout plates contain 2% galactose–2% raffinose and 10 mM 3-AT and lack histidine.