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: Since Rrd1p associates with the coding sequence of GAL1, and promotes the association of RNA polymerase II, transcription of GAL1 would be impaired in the Δrrd1 strain. To test this, we analyzed GAL1 mRNA levels in the wild-type and Δrrd1 strains following transcriptional induction in galactose-containing growth medium. We isolated total RNAs from the wild-type and Δrrd1 strains, and then performed the RT-PCR analysis which revealed significant reduction of GAL1 mRNAs in the Δrrd1 strain (Figure 2A). As a loading control, we show that the mRNA level of a constitutively active ADH1 gene is not altered in the Δrrd1 strain in comparison to the wild-type equivalent (Figure 2A), consistent with previous studies (10) that demonstrated the dispensability of Rrd1p in regulation of transcription under vegetative growth conditions. Thus, our results demonstrate a new role of Rrd1p in promoting transcription of a rapamycin non-responsive GAL1 gene following 90 min transcriptional induction independently of rapamycin treatment (or TOR pathway).
Affiliation: Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.