| 1996 |
PAF53 (POLR1E) interacts with the upstream binding factor UBF in vitro, as demonstrated by Far-Western blotting and GST pull-down assays. Anti-PAF53 antibody blocks specific transcription from the mouse rRNA promoter but not random (non-specific) transcription, establishing PAF53 as required for accurate initiation of Pol I transcription. PAF53 accumulates in the nucleolus of growing cells. |
GST pull-down, Far-Western blotting, antibody inhibition of in vitro transcription, immunofluorescence |
The EMBO journal |
High |
8641287
|
| 1997 |
PAF53 is a constitutive, stoichiometric subunit of RNA Pol I rather than a loosely associated regulatory factor. The molar ratio of PAF53 to the second-largest subunit RPA116 is constant across crude and highly purified Pol I fractions and does not change between exponentially growing and growth-arrested cells. Under all conditions of repressed rDNA transcription tested (serum starvation, actinomycin treatment, mitosis), PAF53 remains attached to the Pol I complex. |
Immunoblot analysis, immunoprecipitation, immunofluorescence, comparison of purified Pol I fractions |
Chromosoma |
High |
9254723
|
| 2000 |
In mouse oocytes, the RNA Pol I subunits RPA116 and PAF53/RPA53 co-localize with UBF within discrete nucleolar foci regardless of transcription status. After germinal vesicle breakdown, the RNA Pol I complex (including PAF53) disassembles from chromosomes in a step-wise manner during meiosis, whereas UBF remains chromosome-associated until late prometaphase I. Neither RNA Pol I nor PAF53 is detectable at metaphase II. |
High-resolution immunofluorescence, confocal microscopy, phosphatase inhibitor (okadaic acid) treatment |
Developmental biology |
Medium |
10882521
|
| 2002 |
Overexpression of the yeast HMG-box protein Hmo1 suppresses the growth defect of rpa49-Δ mutants (lacking the PAF53 yeast orthologue) and strongly increases de novo rRNA synthesis. Double mutants rpa49-Δ hmo1-Δ are lethal, and this lethality is bypassed when RNA Pol II synthesizes rRNA, placing Rpa49/PAF53 and Hmo1 in the same essential Pol I transcription pathway. |
Genetic epistasis, suppressor analysis, rRNA synthesis measurement, double-mutant lethality rescue |
The EMBO journal |
High |
12374750
|
| 2004 |
PAF53 interacts physically with PAF49 through PAF49's N-terminal segment, as demonstrated by co-immunoprecipitation. Both PAF49 and PAF53 co-purify with the transcriptionally active fraction of Pol I. Anti-PAF49 antibody severely impairs specific in vitro transcription from the mouse rRNA promoter, which is rescued by recombinant PAF49. |
Co-immunoprecipitation, co-purification, in vitro transcription assay with antibody inhibition and rescue |
Molecular and cellular biology |
High |
15226435
|
| 2006 |
Acetylation of UBF (occurring in S-phase) augments the interaction between UBF and PAF53 and promotes Pol I recruitment to rDNA. In cells overexpressing HDAC1, UBF is hypoacetylated, co-immunoprecipitation of UBF with anti-PAF53 antibody is abolished, and Pol I association with rDNA and pre-rRNA synthesis are reduced. |
Co-immunoprecipitation, inducible HDAC1 overexpression, ChIP, in vitro pull-down |
Nucleic acids research |
High |
16582105
|
| 2007 |
The yeast Rpa49 (PAF53 orthologue) and Rpa34 subunits form a heterodimer; Rpa34 binds the N-terminal region of Rpa49 in a two-hybrid assay, and Rpa34 is lost from Pol I in an rpa49 mutant lacking this binding domain. The Rpa49–Rpa34 dimer has a dual role: it partially facilitates recruitment of the initiation factor Rrn3 to the rDNA promoter and is required for release of Rrn3 from the elongating polymerase. |
Two-hybrid assay, co-immunoprecipitation, ChIP, genetic mutant analysis, mycophenolate treatment |
Molecular and cellular biology |
High |
18086878
|
| 2010 |
The acetyltransferase hALP acetylates UBF and promotes the association of UBF with PAF53, as well as facilitating nuclear translocation of PAF53 from cytoplasm to nucleus. GST pull-down and co-immunoprecipitation showed that hALP binds UBF in vitro and in vivo. HAT-inactive hALP fails to promote these effects. |
Co-immunoprecipitation, GST pull-down, immunofluorescence (nuclear translocation), HAT-mutant analysis |
The Journal of biological chemistry |
Medium |
21177859
|
| 2011 |
Deletion of RPA49 (PAF53 orthologue) in S. cerevisiae leads to disappearance of nucleolar structure and a fourfold decrease in Pol I loading rate per rDNA gene, as assessed by Miller spread analysis. Human and S. pombe orthologues of Rpa49 functionally complement the S. cerevisiae rpa49-Δ growth defect (heterospecific complementation), demonstrating functional conservation. Reducing rDNA copy number from 190 to 25 restores nucleolar assembly in rpa49-Δ cells. |
Genetic deletion, heterospecific complementation, Miller spread electron microscopy, quantitative statistical analysis of polymerase loading |
The Journal of cell biology |
High |
21263028
|
| 2013 |
SIRT7 deacetylates PAF53 at lysine 373, and CBP acetylates PAF53 at the same residue. Hypoacetylation of PAF53 (by SIRT7) correlates with increased Pol I occupancy on rDNA and transcription activation, while hyperacetylation (upon SIRT7 release from nucleoli under stress) correlates with decreased Pol I transcription. SIRT7 is retained in nucleoli through binding to nascent pre-rRNA; stress conditions release SIRT7 from nucleoli, leading to PAF53 hyperacetylation. |
In vitro deacetylation assay, site-directed mutagenesis (K373), ChIP, co-immunoprecipitation, RNA-binding assay, stress-condition experiments |
Molecular cell |
High |
24207024
|
| 2012 |
PAF53 (and the broader Pol I elongation machinery including Rpa34/Rpa49 in yeast) is characterized as a built-in elongation factor essential for the extremely high rate of rRNA production per gene. The PAF53/CAST heterodimer in humans is the functional counterpart of Rpa34/Rpa49 in yeast for rRNA elongation. |
Review/synthesis of genetic and biochemical data (not a primary experimental paper, but synthesizes established results) |
Genetics research international |
Low |
22567380
|
| 2012 |
In mammalian PAF49 and PAF53, the dimerization interface maps to amino acids 41–86 of PAF49 (sufficient for heterodimerization), consistent with homologous regions in yeast A34.5. Substitution of amino acids 52–98 of yeast A34.5 with amino acids 41–86 of mammalian PAF49 produces a chimeric protein that can heterodimerize with mouse PAF53, demonstrating structural/functional conservation of the dimerization domain. |
Deletion and substitution mutagenesis, co-immunoprecipitation, in silico structural analysis |
Biochemistry |
Medium |
22849406
|
| 2014 |
The PAF49/PAF53 heterodimer interacts physically with the initiation factor Rrn3 (TIF-IA). The acetylation state of PAF49 regulates association of the heterodimer with Pol I: hypoacetylated heterodimer binds Pol I with greater affinity than acetylated heterodimer. Acetylation of PAF49 does not affect PAF49–PAF53 heterodimerization itself. |
Co-immunoprecipitation, acetylation analysis, affinity binding assays |
Gene |
Medium |
25225125
|
| 2016 |
NAT10 autoacetylation at K426 is required for its ability to acetylate UBF, which in turn recruits PAF53 and RNA Pol I to rDNA. The K426R mutant of NAT10 still binds UBF but cannot acetylate it and fails to recruit PAF53 or Pol I to rDNA, resulting in inhibition of pre-rRNA transcription. |
In vitro autoacetylation assay, site-directed mutagenesis (K426R), co-immunoprecipitation, ChIP, pre-rRNA measurement |
Biochemical and biophysical research communications |
Medium |
27993683
|
| 2019 |
PAF53 (mammalian orthologue of yeast Rpa49) is essential for rDNA transcription and mitotic cell growth in mammalian cells, as demonstrated by auxin-inducible degron depletion. All three PAF53 domains are required for function: the C-terminal tandem-winged helix (DNA-binding), the heterodimerization domain, and the linker domain. The linker contains a helix-turn-helix (HTH) motif that constitutes a second DNA-binding domain and is essential for function in both yeast and mammalian orthologues. |
CRISPR/Cas9 + auxin-inducible degron system, domain-deletion mutagenesis, rDNA transcription assays, cell growth assays |
The Journal of biological chemistry |
High |
31727736
|
| 2019 |
In yeast, extragenic suppressors of rpa49-Δ growth defect map to the jaw-lobe module of Pol I (interface between lobe of Rpa135 and jaw of Rpa190/Rpa12), and the suppressor allele Rpa135-F301S restores normal rRNA synthesis and increases Pol I density on rDNA in the absence of Rpa49. In vitro tailed-template assays show Pol I bearing Rpa135-F301S is hyperactive, indicating Rpa49 (PAF53 orthologue) normally acts through this jaw-lobe interface to stimulate Pol I elongation activity. |
Genetic suppressor screen, biochemical rRNA synthesis analysis, in vitro tailed-template transcription assay, ChIP (Pol I density) |
PLoS genetics |
High |
31136569
|
| 2020 |
Pol I mutants lacking the heterodimeric subunit Rpa34.5/Rpa49 (PAF49/PAF53 orthologue) show reduced processivity on naked DNA templates and even further reduced processivity in the presence of a nucleosomal barrier. Purified wild-type Pol I and Pol III (but not Pol II) can transcribe nucleosomal templates; the lobe-binding subunits Rpa34.5/Rpa49 facilitate passage through nucleosomes, suggesting a role for the PAF49/PAF53 heterodimer in chromatin transcription. |
In vitro transcription assays with purified WT and mutant Pol I on naked DNA and nucleosomal templates; comparison with Pol II and Pol III |
The Journal of biological chemistry |
High |
32060094
|
| 2016 |
PAF53 is essential for mammalian cell survival. CRISPR/Cas9-mediated knockout of PAF53 in human 293 cells was only achieved when cells were simultaneously rescued with ectopic FLAG-tagged mouse PAF53. In the absence of ectopic expression, cells employed alternative survival mechanisms (recombination, alternative reading frames) to maintain PAF53 expression, and no clone lacking all PAF53 expression was obtained. |
CRISPR/Cas9 gene editing, DNA sequencing of modified loci, Western blot |
Gene |
Medium |
28042089
|
| 2023 |
PAF49 is essential for rDNA transcription and cell division in mammalian cells. Auxin-induced degradation of PAF49 leads to degradation of its binding partner PAF53 (but not vice versa), demonstrating a co-dependent stability relationship. PAF49 depletion induces nucleolar stress and p53 accumulation. The dimerization domain of PAF49 and an 'arm' domain that interacts with PolR1B are both required for rDNA transcription. Disruption of the PAF49–PolR1B interaction inhibits Pol I transcription and causes cancer cell death while arresting normal cells. |
Auxin-inducible degron system, domain deletion mutagenesis, co-immunoprecipitation, rDNA transcription assays, cell viability assays |
The Journal of biological chemistry |
High |
37356716
|
| 2022 |
In the yeast system, the N-terminal domains of the Rpa34.5/Rpa49 heterodimer (PAF49/PAF53 orthologue) facilitate backtracking and RNA cleavage activity of Pol I in defined in vitro systems. The heterodimer, together with the C-terminal domain of Rpa12.2, is required for transcription fidelity (faithful NTP incorporation), suggesting that efficient backtracking and RNA cleavage enabled by the heterodimer are prerequisites for proofreading. |
In vitro transcription assays with purified mutant Pol I variants, RNA cleavage assays, backtracking assays, fidelity assays |
The Journal of biological chemistry |
High |
35341765
|