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: Based on our above results at GAL1, we expect that Rrd1p would not have an effect on transcription of the constitutively active genes. Indeed, transcription of a constitutively active gene, ADH1, was not altered in the absence of Rrd1p (Figure 4A). Likewise, the association of RNA polymerase II with ADH1 was not changed in the Δrrd1 strain as compared to the wild-type equivalent (Figure 4B). Similarly, transcription of other constitutively active genes, RPS5 and ACT1, was not altered in the Δrrd1 strain (Figure 4C). In an agreement with our results, a recent study (10) has also demonstrated the dispensability of Rrd1p in regulating transcription of the constitutively active genes under vegetative growth conditions. Therefore, the growth of the Δrrd1 strain would not be altered in comparison to the wild-type equivalent in dextrose-containing growth medium. Indeed, the growth of the Δrrd1 strain was not altered in the liquid and solid growth media containing dextrose (Figure 4D and E). Collectively, our results support that Rrd1p promotes initial rounds of GAL1 transcription, but has no effect on steady-state level or constitutive transcription.
Affiliation: Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.