FIG. 4.

Chromatin structure of the ARO4-HIS7 intergenic region at various intracellular Bas protein levels. Yeast cells were grown in the absence of adenine. Lanes: 1 to 3, chromatin of strain RH2029; 4 to 6, chromatin of strain RH1381; 10 to 12, chromatin of strain RH1381 with the BAS1 overexpression plasmid pCB159 (44). On this high-copy-number plasmid the BAS1 open reading frame is fused to the GAL1 promoter. After shifting from glucose to galactose medium, BAS1 expression is strongly induced (44). The location of the promoter region is labeled by Southern hybridizations of chromosomal DNA digested with either XbaI/TaqI or Sau3A.