Figure 2.
Nucleosome organization schematics for the repressed (+Pi) and induced (−Pi) states of PHO promoters. (a) PHO5 promoter organization. Canonical and well-positioned nucleosomes that largely inhibit nuclease access are symbolized by large solid circles and regions of intermediate nuclease accessibility or unclear nucleosome positioning with large stippled circles. Pho4 binding sites (UASp elements) of low and high affinity are represented by open or closed small circles, respectively. Closed squares denote Mcm1 and Fkh2 binding sites and broken arrows induced transcription. sHSS, eHSS and cHSS stand for short, extended and constitutive hypersensitive site, respectively. TSS: transcription start site; ORF: open reading frame; T: TATA box; ClaI: ClaI restriction site. All relative positions approximately to scale. (b), (c) as (a) but for the PHO8 and PHO84 promoter, respectively. See main text for references.