FIG. 7.

KlHap1p controls the transcription of the glucose transporter genes (A) and glucose uptake rate (B) in K. lactis. (A) The wild-type strain MW270-7B and its ΔKlhap1 isogenic mutant were grown aerobically at 28°C in YP medium containing different concentrations of glucose (2% [≈110 mM], 0.2% [≈11 mM], and 0.02% [≈1.1 mM]) as specified. Total RNA was extracted at the exponential phase of growth. Gene probes were obtained by PCR amplification (primers are listed in Table 2). KlACT1 was used as a loading control. Signal quantitation and normalization were carried out as described in Materials and Methods, and the value 1.0 in each panel indicates the reference of normalized intensity with which other signals were compared. Note that HGT1 has two transcripts of different sizes whose precise nature is not known (5). (B) The K. lactis wild-type strain MW270-7B and its ΔKlhap1 isogenic mutant were grown at 28°C in YP-2% glucose. Cells were suspended in phosphate buffer, and the rate of uptake of [¹⁴C]glucose (100 mM) was measured as described in Materials and Methods. The values are means of two independent experiments. In no case was the variation higher than 15% of the mean.