FIG. 1.

Transcription of OLE1 is repressed by O₂ in a Rox1p-independent manner. (A) Northern analysis of the OLE1, OLE1p-PHO5, and ANB1 transcripts in rox1 disruptants. Total RNA samples were prepared from cells of the wild-type strain (SH5420) and rox1 disruptant (SH5421) cultivated aerobically (lanes 1 and 2) or anaerobically (lanes 3 and 4) in YPDA medium. Equal amounts of RNA (5 μg) were electrophoresed in a 1.5% agarose gel in the presence of formaldehyde, transferred to a nylon filter, blotted, and hybridized with probes consisting of ³²P-labeled DNA fragments containing OLE1, ANB1, and PHO5 for detection of the transcripts of OLE1p-PHO5 or ACT1 as an internal control. The ANB1 probe also hybridized to the TIF51A transcript, which is not repressed by Rox1p (53). (B) Putative Rox1p binding sites in the OLE1 promoter. Numbers indicate positions relative to the first nucleotide of the initiation codon (+1). Lowercase letters, nucleotides that differ from the consensus Rox1p-binding sequence (3).