Rpa49, also characterized as RPA51, is a Pol I-specific accessory subunit in the nucleolus. It supports efficient ribosomal DNA transcription and transcription elongation by RNA polymerase I. It is functionally conserved with budding-yeast A49 and acts within the polymerase complex rather than providing an independent RNA-polymerase catalytic center.
Existing Annotations Review
GO Term
Evidence
Action
Reason
GO:0001188 RNA polymerase I preinitiation complex assembly
IBA GO_REF:0000033
ACCEPT
Summary: RNA polymerase I preinitiation complex assembly is supported.
Reason: Budding-yeast A49/A34 promotes recruitment of Rrn3 and its release during elongation (PMID:18086878). Functional complementation by fission-yeast RPA51 (PMID:12893961) supports the PAINT transfer of conserved Pol I preinitiation participation. This remains a homolog-based process inference rather than a target preinitiation assay.
rpa51+ is required for cell growth at lower but not at higher temperatures and is able to complement S. cerevisiae rpa49Delta mutation, indicating that RPA51 is a functionally-conserved subunit of Pol I between the budding yeast and the fission yeast.
Reason: The characterized budding-yeast A49 C-terminal tandem-winged-helix domain binds DNA (PMID:20797630). Fission-yeast RPA51 complements the budding-yeast rpa49 deletion (PMID:12893961), and the target has the diagnostic A49-family domain. Together these justify conserved DNA-binding activity by family transfer, without asserting a target-specific promoter preference.
The C-terminal region of A49 forms a "tandem winged helix" (tWH) domain that binds DNA with a preference for the upstream promoter nontemplate strand and is predicted in TFIIE.
rpa51+ is required for cell growth at lower but not at higher temperatures and is able to complement S. cerevisiae rpa49Delta mutation, indicating that RPA51 is a functionally-conserved subunit of Pol I between the budding yeast and the fission yeast.
HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ...
ACCEPT
Summary: nucleus is supported.
Reason: Nuclear localization is compatible with Pol I subunit membership and rDNA transcription. The genome-scale localization annotation is retained; the abstract does not independently expose the individual image. The source excerpt records the target HDA/IC annotation, not a reinspection of the individual microscopy image.
HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ...
ACCEPT
Summary: nucleolus is supported.
Reason: Nucleolar residence is consistent with the direct Pol I/rDNA-transcription role and the curated localization experiment. The source excerpt records the target HDA/IC annotation, not a reinspection of the individual microscopy image.
We also found that RPA51 associates significantly with Pol I in the stationary phase, suggesting that Pol I inactivation in the stationary phase of yeast does not result from the RPA51 dissociation.
We also found that RPA51 associates significantly with Pol I in the stationary phase, suggesting that Pol I inactivation in the stationary phase of yeast does not result from the RPA51 dissociation.
Summary: DNA-templated transcription is reviewed in the context of rpa49.
Reason: The broad DNA-templated transcription annotation is compatible with the biology, but transcription elongation by RNA polymerase I captures the supported rpa49 function more precisely.
Transcripts analysis in vivo and in vitro shows that RPA51 plays a general role for maximizing transcription of rDNA whereas it is dispensable for non-specific transcription.
GO:0006362 transcription elongation by RNA polymerase I
IBA GO_REF:0000033
ACCEPT
Summary: transcription elongation by RNA polymerase I is supported.
Reason: The paper identifies RPA51 as a functionally conserved Pol I subunit required for maximal rDNA transcription. Retain PomBase's experimental elongation assignment and the concordant PAINT inference; the subunit supports the polymerase rather than catalyzing RNA synthesis independently.
Transcripts analysis in vivo and in vitro shows that RPA51 plays a general role for maximizing transcription of rDNA whereas it is dispensable for non-specific transcription.
GO:0006362 transcription elongation by RNA polymerase I
IDA PMID:12893961 The fission yeast RPA51 is a functional homolog of the buddi...
ACCEPT
Summary: transcription elongation by RNA polymerase I is supported.
Reason: The paper identifies RPA51 as a functionally conserved Pol I subunit required for maximal rDNA transcription. Retain PomBase's experimental elongation assignment and the concordant PAINT inference; the subunit supports the polymerase rather than catalyzing RNA synthesis independently.
Transcripts analysis in vivo and in vitro shows that RPA51 plays a general role for maximizing transcription of rDNA whereas it is dispensable for non-specific transcription.
Core Functions
Supports efficient Pol I transcription of ribosomal DNA as the conserved A49 accessory subunit.
Transcripts analysis in vivo and in vitro shows that RPA51 plays a general role for maximizing transcription of rDNA whereas it is dispensable for non-specific transcription.
These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.
Review rationale: S. pombe RPA51/Rpa49 is an experimentally established Pol I subunit required for efficient rDNA transcription (PMID:12893961). The predicted DNA-directed RNA polymerase complex is biologically supported. The existing RNA polymerase I complex annotation is more specific within the same GO aspect, so the prediction is LSP. This is a process/complex assignment to an accessory subunit, not independent polymerase catalysis.
Supporting Evidence:
PMID:12893961: "Transcripts analysis in vivo and in vitro shows that RPA51 plays a general role for maximizing transcription of rDNA whereas it is dispensable for non-specific transcription."
Review rationale: S. pombe RPA51/Rpa49 is an experimentally established Pol I subunit required for efficient rDNA transcription (PMID:12893961). The predicted DNA-templated transcription is biologically supported. The existing transcription elongation by RNA polymerase I annotation is more specific within the same GO aspect, so the prediction is LSP. This is a process/complex assignment to an accessory subunit, not independent polymerase catalysis.
Supporting Evidence:
PMID:12893961: "Transcripts analysis in vivo and in vitro shows that RPA51 plays a general role for maximizing transcription of rDNA whereas it is dispensable for non-specific transcription."