Conditional depletion of the RNA polymerase I subunit PAF53 reveals that it is essential for mitosis and enables identification of functional domains

Abstract

Our knowledge of the mechanism of rDNA transcription has benefited from the combined application of genetic and biochemical techniques in yeast. Nomura's laboratory (Nogi, Y.,

The Mammalian and Yeast A49 and A34 Heterodimers: Homologous but Not the Same

“…Studies in yeast have demonstrated that A49 can be recruited to the polymerase independently of A34. For example, the deletion of the heterodimerization domain does not affect proliferation [21,38]. However, deletion of the dimerization domain of PAF53 significantly inhibited prolifer- Interestingly, the tWH domains of TFIIE and A49 both lie upstream of the transcription initiation site, and the linker domains of TFIIF and TFIIE appear to span the polymerase cleft in a manner similar to the HTH of A49.…”

“…Our demonstration that PAF49 is essential for growth and transcription while its ortholog, yeast A34, is nonessential, highlights the importance of further studying Pol I transcription in mammals. [38]. Cells were treated with or without indole-3 acetic acid (IAA) for 3 h. Whole-cell extracts were prepared, and levels of PAF49 were determined via Western blot analysis.…”

“…Before Pol I binds to the promoter, it must first form a complex with Rrn3, a polymerase-associated factor that is released once transcription has been initiated [52]. It has been hypothesized that the het- [38]. Cells were treated with or without indole-3 acetic acid (IAA) for 3 h. Whole-cell extracts were prepared, and levels of PAF49 were determined via Western blot analysis.…”

“…They also demonstrated that a tandem winged helix (tWH) found in the C-terminal domain of A49 had DNA-binding activity and increased the processivity of Pol I, both of which are properties of TFIIE. In their analysis of the domains of PAF53, McNamar et al [ 38 ] found that the predicted tWH of mammalian PAF53 also had DNA-binding activity, and that this domain was essential for full activity. They also found that both the dimerization domain and the linker region were essential for full activity.…”

“…Studies in yeast have demonstrated that A49 can be recruited to the polymerase independently of A34. For example, the deletion of the heterodimerization domain does not affect proliferation [ 21 , 38 ]. However, deletion of the dimerization domain of PAF53 significantly inhibited proliferation [ 38 ].…”