Fig 5.

Nrd1-Nab3 represses CLN3 in response to nutrient depletion. (A) PAR-CLIP data showing that Nrd1 binds to an upstream CUT and to the 5′ UTR of CLN3. Nab3 binds to the 5′ end of the CLN3 coding region. Vertical lines indicate the numbers of transcripts bound at each location by Nrd1 and Nab3 per 10⁷ aligned PAR-CLIP sequencing reads (19). (B to D) Levels of CLN3 mRNA are slower to decrease in nab3-42 than in NAB3 cells after transfer from YPD at the permissive temperature of 28°C to water at the nonpermissive temperature of 37°C (B) or from SC with glucose at 28°C to SC lacking glucose at 37°C (D), resulting in a greater relative overabundance of CLN3 in these samples than after the temperature change alone (C). (E) CLN3 is also overabundant in nrd1-102 relative to NRD1 cells after transfer from YPD at 28°C to water at 37°C. In panels B to E, the numbers above each pair of columns represent fold overabundances of CLN3 in the temperature-sensitive mutant compared to the wild type at each time point. Total RNA was collected before the medium transfer and at 20-min intervals and analyzed by qRT-PCR. Relative expression was normalized to the expression level of the 18S rRNA gene and was set to 1 for the initial wild-type sample. Error bars represent standard errors of the means from two independent experiments.