The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
The S. pombe gene pol5+ (SPBC14C8.14c; UniProt O60094) encodes an essential, predominantly nuclear protein historically annotated as “DNA polymerase V/φ,” but experimental and comparative evidence supports its primary role in ribosomal DNA (rDNA) / rRNA production and ribosome biogenesis. In fission yeast, Pol5 is essential for viability, localizes to the nucleus in GFP-fusion studies, physically interacts with the cell-cycle transcription factor Cdc10, and is regulated by Eso1-mediated lysine acetylation at an essential conserved residue (K47). While direct mechanistic mapping of Pol5 to pre-ribosomal particles is currently strongest in budding yeast, these conserved functional data plus S. pombe genetics strongly support annotating fission-yeast Pol5 as a conserved ribosome biogenesis/rDNA transcription regulator rather than a replicative DNA polymerase. (nadeem2005pol5+apotential pages 199-202, nadeem2005pol5+apotential pages 1-9, chen2017dnapolymerase5 pages 3-6)
Evidence from multiple S. pombe sources indicates that pol5+ corresponds to SPBC14C8.14c and to the Pol5 protein described in the user’s UniProt context:
- A genome-scale GFP-fusion localization study lists SPBC14C8.14c (clone TC48) annotated as “DNA polymerase V” under a nuclear category, consistent with the historical Pol5 naming. (ding2000large‐scalescreeningof media e191a246, ding2000large‐scalescreeningof media b2dd5871)
- A S. pombe genetic/biochemical study of Pol5 acetylation by Eso1 explicitly studies “Pol5” in S. pombe and demonstrates essentiality of a conserved residue. (chen2017dnapolymerase5 pages 3-6, chen2017dnapolymerase5 pages 1-2)
- A fission-yeast thesis explicitly studies pol5+, reporting essentiality, nuclear localization, and interaction with Cdc10. (nadeem2005pol5+apotential pages 1-9)
Taken together, the most evidence-consistent annotation for S. pombe Pol5 is: essential nuclear (likely nucleolar) ribosome biogenesis/rDNA transcription-associated factor, rather than a classical DNA polymerase. (nadeem2005pol5+apotential pages 1-9, ramossaenz2019pol5isan pages 1-2)
Chen et al. (2017; publication date Dec 2017; International Journal of Molecular Medicine; https://doi.org/10.3892/ijmm.2017.3192) provide the most direct molecular mechanistic evidence for Pol5 regulation in S. pombe:
- Pol5 is lysine-modified: Mass spectrometry on Pol5 identified multiple lysine acetylation/trimethylation sites; K47 had a reported 100% modification ratio and is conserved with budding-yeast Pol5 (K53). (chen2017dnapolymerase5 pages 3-6)
- Eso1/Eco1 can acetylate Pol5 in vitro: Immunoprecipitated Pol5-HA incubated with recombinant Eco1 in HAT buffer plus acetyl-CoA yielded an anti–acetyl-lysine signal, consistent with direct acetylation. (chen2017dnapolymerase5 pages 2-3)
- K47 is essential and linked to acetylation state: A K47R non-acetylatable mutation is lethal (tetrad/selection-based evidence); a K47N acetyl-mimic supported normal growth, and plasmid-borne WT Pol5 rescued K47R dependence. (chen2017dnapolymerase5 pages 3-6)
Direct Pol5-focused primary research in 2023–2024 was not retrieved in the available corpus; however, several high-authority 2023–2024 studies and reviews sharpen the systems-level context for Pol5’s inferred role (rDNA transcription/ribosome biogenesis) in S. pombe.
Hirai & Ohta (2023; publication date Feb 2023; Biomolecules; https://doi.org/10.3390/biom13020288) emphasize:
- TOR-dependent control of rRNA and ribosomal protein gene expression; rapamycin/TOR inhibition rapidly downregulates ribosome-related transcription, and S. pombe TORC1 (Tor2) is highlighted as a primary regulator of ribosome-related genes. (hirai2023comparativeresearchregulatory pages 2-4)
- Heterochromatin/RNAi layers that are prominent in fission yeast (Clr4-mediated H3K9 methylation and HP1 proteins) and can repress ribosomal genes/rDNA repeats during starvation; e.g., starvation-linked dissociation of activators (Atf1/Gcn5) and increased H3K9 methylation with FACT involvement. (hirai2023comparativeresearchregulatory pages 11-13, hirai2023comparativeresearchregulatory pages 9-11)
The review does not specifically place Pol5 into these pathways, but it defines the regulatory environment in which Pol5-dependent rRNA output would be controlled. (hirai2023comparativeresearchregulatory pages 2-4)
Yague-Sanz (2024; publication date Dec 2024; Yeast; https://doi.org/10.1002/yea.3921) proposes a model for S. pombe rDNA heterochromatinization in starvation in which:
- RNAPI dissociates from rDNA during starvation;
- pervasive local RNAPII transcription at rDNA (e.g., pausing near 5′ETS) may recruit factors (CCR4-NOT) and small-RNA pathways that promote Clr4-dependent H3K9 methylation and Clr3-dependent deacetylation. (yague‐sanz2024shapingthechromatin pages 9-9)
This suggests additional regulatory layers linking transcriptional activity at rDNA to chromatin state, relevant to any factor (including Pol5) proposed to couple transcription and processing. (yague‐sanz2024shapingthechromatin pages 9-9)
Cockrell et al. (2024; publication date Jul 2024; PLOS Genetics; https://doi.org/10.1371/journal.pgen.1011331) provide quantitative tools and findings that are immediately relevant to Pol5’s functional neighborhood:
- rDNA copy number context: WT lab strains contain ~80–120 rRNA genes across the two chromosome III rDNA arrays. (cockrell2024regulatorsofrdna pages 2-3)
- Perturbations that change rDNA/nucleolus morphology: RNA Pol I inhibition (actinomycin D) and glucose starvation drive rDNA condensation/nucleolar shrinkage, while TOR hyperactivation (tsc1Δ/tsc2Δ) expands rDNA volume and GapR-GFP intensity. (cockrell2024regulatorsofrdna pages 8-10)
- Genome-scale implementation: The authors screened the Bioneer haploid deletion collection (~3,400 nonessential deletions) using a live imaging marker (GapR-GFP) for rDNA spatial organization phenotypes. (cockrell2024regulatorsofrdna pages 8-10)
- Quantitative/statistical practice: Example quantifications used n>314 cells with Kruskal–Wallis testing across replicates; follow-up RPL mutant quantifications used >50 cells per replicate. (cockrell2024regulatorsofrdna pages 8-10, cockrell2024regulatorsofrdna pages 12-15)
- Signaling cross-talk: RPL gene deletions (ribosomal protein insufficiency) produced strong nucleolar/rDNA phenotypes and correlated with resistance to TOR inhibition (Torin1 10–12.5 μM), with genetic analysis implicating the Pmk1 MAPK pathway as a modulator of compensatory ribosome biogenesis. (cockrell2024regulatorsofrdna pages 12-15, cockrell2024regulatorsofrdna pages 15-17)
Although Pol5 is not the direct subject, these methods are directly applicable to testing Pol5 conditional alleles for effects on rDNA morphology and TOR-linked adaptation. (cockrell2024regulatorsofrdna pages 8-10)
In yeast molecular/cell biology, Pol5-related knowledge is applied primarily as:
The following table consolidates direct S. pombe evidence and cross-species mechanistic support.
| Evidence type | Key finding | Experimental approach/system | Species | Source (authors, year, journal) | URL/DOI |
|---|---|---|---|---|---|
| Identity / annotation | SPBC14C8.14c was recovered in a GFP-fusion localization screen and annotated there as “DNA polymerase V,” matching the historical Pol5 naming used for the fission-yeast gene; however, the screen excerpt does not unambiguously assign a localization category to this entry. (ding2000large‐scalescreeningof pages 7-10) | GFP-fusion genomic DNA library screen; clone TC48; fusion position 795/959 | S. pombe | Ding et al., 2000, Genes to Cells | https://doi.org/10.1046/j.1365-2443.2000.00317.x |
| Essentiality | pol5+ is reported as essential for viability in fission yeast. (nadeem2005pol5+apotential pages 199-202, nadeem2005pol5+apotential pages 1-9) | Gene disruption and conditional-expression analyses summarized in thesis work | S. pombe | Nadeem, 2005, thesis | URL not available in retrieved context |
| Localization | GFP-tagged SpPol5p localized to the nucleus; nucleolar localization was proposed but not conclusively demonstrated in the thesis. (nadeem2005pol5+apotential pages 199-202, nadeem2005pol5+apotential pages 1-9) | GFP tagging / fluorescence localization | S. pombe | Nadeem, 2005, thesis | URL not available in retrieved context |
| Interaction / complex | SpPol5p physically interacts with the C-terminus of the cell-cycle transcription factor Cdc10p, suggesting a link between cell-cycle control and growth/rRNA production. (nadeem2005pol5+apotential pages 116-121, nadeem2005pol5+apotential pages 1-9) | Yeast two-hybrid, co-immunoprecipitation, GST pull-down | S. pombe | Nadeem, 2005, thesis | URL not available in retrieved context |
| Functional evidence | pol5+ mRNA is constitutive and low abundance; overexpression perturbs rRNA production, supporting a role in rRNA synthesis/ribosome biogenesis rather than a conventional DNA polymerase role. (nadeem2005pol5+apotential pages 199-202, nadeem2005pol5+apotential pages 1-9) | Northern blot; overexpression and shut-off experiments; pulse-chase rRNA labeling | S. pombe | Nadeem, 2005, thesis | URL not available in retrieved context |
| PTM / essential residue | Pol5 is an Eso1 interaction partner and acetylation substrate; mutation of conserved Lys47 to Arg was lethal, indicating an essential role for this residue/modification state in viability. (chen2017dnapolymerase5 pages 1-2) | TAP purification, immunoprecipitation, LC-MS/MS, site-directed mutagenesis, tetrad analysis | S. pombe | Chen et al., 2017, International Journal of Molecular Medicine | https://doi.org/10.3892/ijmm.2017.3192 |
| Pathway context | Recent review of fission-yeast ribosomal gene regulation emphasizes TOR-responsive repression of ribosome-related transcription, starvation-induced chromatin remodeling, and rDNA heterochromatin/RNAi pathways; Pol5 is not specifically placed in these pathways in the review. (hirai2023comparativeresearchregulatory pages 2-4, hirai2023comparativeresearchregulatory pages 9-11, hirai2023comparativeresearchregulatory pages 1-2) | Comparative review of primary literature | S. pombe | Hirai & Ohta, 2023, Biomolecules | https://doi.org/10.3390/biom13020288 |
| Cross-species function inference | Budding-yeast Pol5 is an essential nucleolar trans-acting factor for 60S subunit maturation; depletion causes 60S deficiency, half-mer polysomes, defective 27SB→25S processing, and impaired pre-60S export. This strongly supports annotating S. pombe Pol5 as a ribosome-biogenesis factor. (ramossaenz2019pol5isan pages 8-9, ramossaenz2019pol5isan pages 1-2) | Depletion and temperature-sensitive mutants; polysome analysis; pre-rRNA processing assays; genetic suppression | S. cerevisiae | Ramos-Sáenz et al., 2019, RNA | https://doi.org/10.1261/rna.072116.119 |
| Cross-species mechanistic inference | Budding-yeast Pol5 binds the 5′ ETS and domain III of 25S rRNA, promotes peptide-exit-tunnel assembly in the LSU, and supports recycling of pre-40S factors; these data argue that Pol5 family proteins act in ribosome assembly, not replicative DNA synthesis. (braun2020pol5isrequired pages 1-2) | Pol5 depletion, RNA binding-site mapping, pre-rRNA processing analyses | S. cerevisiae | Braun et al., 2020, Nucleic Acids Research | https://doi.org/10.1093/nar/gkz1079 |
Table: This table compiles the strongest directly supported evidence for functional annotation of Schizosaccharomyces pombe Pol5 (O60094/SPBC14C8.14c), separating organism-specific findings from cross-species inference. It is useful for distinguishing firm experimental evidence in fission yeast from broader pathway context and conserved Pol5-family function.
References
(nadeem2005pol5+apotential pages 199-202): FK Nadeem. Pol5+, a potential link between cell cycle and cell growth in fission yeast. Unknown journal, 2005.
(nadeem2005pol5+apotential pages 1-9): FK Nadeem. Pol5+, a potential link between cell cycle and cell growth in fission yeast. Unknown journal, 2005.
(chen2017dnapolymerase5 pages 3-6): Zhiming Chen, Hongshi Cao, Yingqiang Lu, Qiang Ren, and Liankun Sun. Dna polymerase 5 acetylation by eso1 is essential for schizosaccharomyces pombe viability. International journal of molecular medicine, 40 6:1907-1913, Dec 2017. URL: https://doi.org/10.3892/ijmm.2017.3192, doi:10.3892/ijmm.2017.3192. This article has 2 citations and is from a peer-reviewed journal.
(nadeem2005pol5+apotential pages 116-121): FK Nadeem. Pol5+, a potential link between cell cycle and cell growth in fission yeast. Unknown journal, 2005.
(ramossaenz2019pol5isan pages 1-2): Ana Ramos-Sáenz, Daniel González-Álvarez, Olga Rodríguez-Galán, Alfonso Rodríguez-Gil, Sonia G. Gaspar, Eduardo Villalobo, Mercedes Dosil, and Jesús de la Cruz. Pol5 is an essential ribosome biogenesis factor required for 60s ribosomal subunit maturation in saccharomyces cerevisiae. RNA, 25:1561-1575, Aug 2019. URL: https://doi.org/10.1261/rna.072116.119, doi:10.1261/rna.072116.119. This article has 18 citations and is from a domain leading peer-reviewed journal.
(ding2000large‐scalescreeningof media e191a246): Da‐Qiao Ding, Yuki Tomita, Ayumu Yamamoto, Yuji Chikashige, Tokuko Haraguchi, and Yasushi Hiraoka. Large‐scale screening of intracellular protein localization in living fission yeast cells by the use of a gfp‐fusion genomic dna library. Genes to Cells, 5:169-190, Mar 2000. URL: https://doi.org/10.1046/j.1365-2443.2000.00317.x, doi:10.1046/j.1365-2443.2000.00317.x. This article has 171 citations and is from a peer-reviewed journal.
(braun2020pol5isrequired pages 1-2): Christina M. Braun, Philipp Hackert, Catharina E. Schmid, Markus T. Bohnsack, Katherine E. Bohnsack, and Jorge Perez-Fernandez. Pol5 is required for recycling of small subunit biogenesis factors and for formation of the peptide exit tunnel of the large ribosomal subunit. Nucleic Acids Research, 48:405-420, Nov 2020. URL: https://doi.org/10.1093/nar/gkz1079, doi:10.1093/nar/gkz1079. This article has 21 citations and is from a highest quality peer-reviewed journal.
(hirai2023comparativeresearchregulatory pages 1-2): Hayato Hirai and Kunihiro Ohta. Comparative research: regulatory mechanisms of ribosomal gene transcription in saccharomyces cerevisiae and schizosaccharomyces pombe. Biomolecules, 13:288, Feb 2023. URL: https://doi.org/10.3390/biom13020288, doi:10.3390/biom13020288. This article has 19 citations.
(hirai2023comparativeresearchregulatory pages 2-4): Hayato Hirai and Kunihiro Ohta. Comparative research: regulatory mechanisms of ribosomal gene transcription in saccharomyces cerevisiae and schizosaccharomyces pombe. Biomolecules, 13:288, Feb 2023. URL: https://doi.org/10.3390/biom13020288, doi:10.3390/biom13020288. This article has 19 citations.
(ding2000large‐scalescreeningof media b2dd5871): Da‐Qiao Ding, Yuki Tomita, Ayumu Yamamoto, Yuji Chikashige, Tokuko Haraguchi, and Yasushi Hiraoka. Large‐scale screening of intracellular protein localization in living fission yeast cells by the use of a gfp‐fusion genomic dna library. Genes to Cells, 5:169-190, Mar 2000. URL: https://doi.org/10.1046/j.1365-2443.2000.00317.x, doi:10.1046/j.1365-2443.2000.00317.x. This article has 171 citations and is from a peer-reviewed journal.
(chen2017dnapolymerase5 pages 1-2): Zhiming Chen, Hongshi Cao, Yingqiang Lu, Qiang Ren, and Liankun Sun. Dna polymerase 5 acetylation by eso1 is essential for schizosaccharomyces pombe viability. International journal of molecular medicine, 40 6:1907-1913, Dec 2017. URL: https://doi.org/10.3892/ijmm.2017.3192, doi:10.3892/ijmm.2017.3192. This article has 2 citations and is from a peer-reviewed journal.
(chen2017dnapolymerase5 pages 2-3): Zhiming Chen, Hongshi Cao, Yingqiang Lu, Qiang Ren, and Liankun Sun. Dna polymerase 5 acetylation by eso1 is essential for schizosaccharomyces pombe viability. International journal of molecular medicine, 40 6:1907-1913, Dec 2017. URL: https://doi.org/10.3892/ijmm.2017.3192, doi:10.3892/ijmm.2017.3192. This article has 2 citations and is from a peer-reviewed journal.
(hirai2023comparativeresearchregulatory pages 11-13): Hayato Hirai and Kunihiro Ohta. Comparative research: regulatory mechanisms of ribosomal gene transcription in saccharomyces cerevisiae and schizosaccharomyces pombe. Biomolecules, 13:288, Feb 2023. URL: https://doi.org/10.3390/biom13020288, doi:10.3390/biom13020288. This article has 19 citations.
(hirai2023comparativeresearchregulatory pages 9-11): Hayato Hirai and Kunihiro Ohta. Comparative research: regulatory mechanisms of ribosomal gene transcription in saccharomyces cerevisiae and schizosaccharomyces pombe. Biomolecules, 13:288, Feb 2023. URL: https://doi.org/10.3390/biom13020288, doi:10.3390/biom13020288. This article has 19 citations.
(yague‐sanz2024shapingthechromatin pages 9-9): Carlo Yague‐Sanz. Shaping the chromatin landscape at rrna and trna genes, an emerging new role for rna polymerase ii transcription? Yeast, 41:135-147, Dec 2024. URL: https://doi.org/10.1002/yea.3921, doi:10.1002/yea.3921. This article has 7 citations and is from a peer-reviewed journal.
(cockrell2024regulatorsofrdna pages 2-3): Alexandria J. Cockrell, Jeffrey J. Lange, Christopher Wood, Mark Mattingly, Scott M. McCroskey, William D. Bradford, Juliana Conkright-Fincham, Lauren Weems, Monica S. Guo, and Jennifer L. Gerton. Regulators of rdna array morphology in fission yeast. PLOS Genetics, 20:e1011331, Jul 2024. URL: https://doi.org/10.1371/journal.pgen.1011331, doi:10.1371/journal.pgen.1011331. This article has 4 citations and is from a domain leading peer-reviewed journal.
(cockrell2024regulatorsofrdna pages 8-10): Alexandria J. Cockrell, Jeffrey J. Lange, Christopher Wood, Mark Mattingly, Scott M. McCroskey, William D. Bradford, Juliana Conkright-Fincham, Lauren Weems, Monica S. Guo, and Jennifer L. Gerton. Regulators of rdna array morphology in fission yeast. PLOS Genetics, 20:e1011331, Jul 2024. URL: https://doi.org/10.1371/journal.pgen.1011331, doi:10.1371/journal.pgen.1011331. This article has 4 citations and is from a domain leading peer-reviewed journal.
(cockrell2024regulatorsofrdna pages 12-15): Alexandria J. Cockrell, Jeffrey J. Lange, Christopher Wood, Mark Mattingly, Scott M. McCroskey, William D. Bradford, Juliana Conkright-Fincham, Lauren Weems, Monica S. Guo, and Jennifer L. Gerton. Regulators of rdna array morphology in fission yeast. PLOS Genetics, 20:e1011331, Jul 2024. URL: https://doi.org/10.1371/journal.pgen.1011331, doi:10.1371/journal.pgen.1011331. This article has 4 citations and is from a domain leading peer-reviewed journal.
(cockrell2024regulatorsofrdna pages 15-17): Alexandria J. Cockrell, Jeffrey J. Lange, Christopher Wood, Mark Mattingly, Scott M. McCroskey, William D. Bradford, Juliana Conkright-Fincham, Lauren Weems, Monica S. Guo, and Jennifer L. Gerton. Regulators of rdna array morphology in fission yeast. PLOS Genetics, 20:e1011331, Jul 2024. URL: https://doi.org/10.1371/journal.pgen.1011331, doi:10.1371/journal.pgen.1011331. This article has 4 citations and is from a domain leading peer-reviewed journal.
(ding2000large‐scalescreeningof pages 7-10): Da‐Qiao Ding, Yuki Tomita, Ayumu Yamamoto, Yuji Chikashige, Tokuko Haraguchi, and Yasushi Hiraoka. Large‐scale screening of intracellular protein localization in living fission yeast cells by the use of a gfp‐fusion genomic dna library. Genes to Cells, 5:169-190, Mar 2000. URL: https://doi.org/10.1046/j.1365-2443.2000.00317.x, doi:10.1046/j.1365-2443.2000.00317.x. This article has 171 citations and is from a peer-reviewed journal.
(ramossaenz2019pol5isan pages 8-9): Ana Ramos-Sáenz, Daniel González-Álvarez, Olga Rodríguez-Galán, Alfonso Rodríguez-Gil, Sonia G. Gaspar, Eduardo Villalobo, Mercedes Dosil, and Jesús de la Cruz. Pol5 is an essential ribosome biogenesis factor required for 60s ribosomal subunit maturation in saccharomyces cerevisiae. RNA, 25:1561-1575, Aug 2019. URL: https://doi.org/10.1261/rna.072116.119, doi:10.1261/rna.072116.119. This article has 18 citations and is from a domain leading peer-reviewed journal.