Rrd1p, an RNA polymerase II-specific prolyl isomerase and activator of phosphoprotein phosphatase, promotes transcription independently of rapamycin response.
Bottom Line: Similarly, inducible, but rapamycin-responsive, non-GAL genes such as CTT1, STL1 and CUP1 are also regulated by Rrd1p.Consistently, transcription of the constitutively active genes is not changed in the Δrrd1 strain.Taken together, our results demonstrate a new function of Rrd1p in stimulation of initial rounds of transcription, but not steady-state/constitutive transcription, of both rapamycin-responsive and non-responsive genes independently of rapamycin treatment.
Affiliation: Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.Show MeSH
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Mentions: We next asked whether the effect of Rrd1p on transcription of GAL7 and GAL10 is minimal or absent when the steady-state is reached after a long induction in galactose-containing growth medium. To address this, both the wild-type and Δrrd1 strains were continuously grown in galactose-containing growth medium up to an OD600 of 1.0 prior to harvesting for RT-PCR analysis. We found that transcription of GAL7 and GAL10 in the Δrrd1 strain reached the wild-type level when the steady-state is reached after a long transcriptional induction (Figure 5H). Thus, Rrd1p promotes the initial rounds of GAL7 and GAL10 transcription, and has no effect on transcription when the steady-state is reached. This is further corroborated by the kinetic analysis of RNA polymerase II association with GAL7 and GAL10 following short or long transcriptional induction (Figure 6A–D). Moreover, the role of Rrd1p in stimulation of RNA polymerase II association with GAL7 and GAL10 is correlated with facilitated nucleosomal disassembly as the eviction of histone H2B from GAL7 and GAL10 is impaired in the Δrrd1 strain in comparison to the wild-type equivalent (Figure 6E and F).
Affiliation: Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.