TOP3 / YLR234W Overview
- Standard Name
- TOP3 6
- Systematic Name
- YLR234W
- SGD ID
- SGD:S000004224
- Aliases
- EDR1 1
- Feature Type
- ORF , Verified
- EC Number
- 5.6.2.1
- Description
- DNA Topoisomerase III; conserved protein that functions in a complex with Sgs1p and Rmi1p to relax single-stranded negatively-supercoiled DNA preferentially; DNA catenation/decatenation activity is stimulated by RPA and Sgs1p-Top3p-Rmi1p; involved in telomere stability and regulation of mitotic recombination 1 2 3 4 5
- Name Description
- TOPoisomerase 1
- Comparative Info
-
Sequence
The S. cerevisiae Reference Genome sequence is derived from laboratory strain S288C. Download DNA or protein sequence, view genomic context and coordinates. Click "Sequence Details" to view all sequence information for this locus, including that for other strains.
Analyze Sequence
S288C only
BLASTN | BLASTP | Design Primers | Restriction Fragment Map | Restriction Fragment Sizes | Six-Frame Translation
S288C vs. other species
BLASTN vs. fungi | BLASTP at NCBI | BLASTP vs. fungi | CGD Synteny Browser
S288C vs. other strains
Protein
Basic sequence-derived (length, molecular weight, isoelectric point) and experimentally-determined (median abundance, median absolute deviation) protein information. Click "Protein Details" for further information about the protein such as half-life, abundance, domains, domains shared with other proteins, protein sequence retrieval for various strains, physico-chemical properties, protein modification sites, and external identifiers for the protein.
- Summary
- DNA Topoisomerase III is 656 amino acids long and extremely low in abundance; phosphorylated on S103 and S372, and sumoylated on K213 and K339
Alleles
Curated mutant alleles for the specified gene, listed alphabetically. Click on the allele name to open the allele page. Click "SGD search" to view all alleles in search results.
View all TOP3 alleles in SGD search
Gene Ontology
GO Annotations consist of four mandatory components: a gene product, a term from one of the three Gene Ontology (GO) controlled vocabularies (Molecular Function, Biological Process, and Cellular Component), a reference, and an evidence code. SGD has manually curated and high-throughput GO Annotations, both derived from the literature, as well as computational, or predicted, annotations. Click "Gene Ontology Details" to view all GO information and evidence for this locus as well as biological processes it shares with other genes.
- Summary
- Type I DNA topoisomerase involved in DNA topological change and mitotic sister chromatid cohesion; role in telomere maintenance via recombination, telomere maintenance via telomerase, reciprocal meiotic recombination and regulation of DNA recombination; subunit of RecQ family helicase-topoisomerase III complex
View computational annotations
Molecular Function
- Manually Curated
Biological Process
- Manually Curated
- involved in DNA topological change (IDA)
- involved in mitotic sister chromatid cohesion (IMP)
- involved in reciprocal meiotic recombination (IMP)
- involved in regulation of DNA recombination (IMP)
- involved in telomere maintenance via recombination (IGI)
- involved in telomere maintenance via telomerase (IMP)
Cellular Component
- Manually Curated
- part of RecQ family helicase-topoisomerase III complex (IPI, IDA)
Complex
Macromolecular complex annotations are imported from the Complex Portal. These annotations have been derived from physical molecular interaction evidence extracted from the literature and cross-referenced in the entry, or by curator inference from information on homologs in closely related species or by inference from scientific background.
Phenotype
Phenotype annotations for a gene are curated single mutant phenotypes that require an observable (e.g., "cell shape"), a qualifier (e.g., "abnormal"), a mutant type (e.g., null), strain background, and a reference. In addition, annotations are classified as classical genetics or high-throughput (e.g., large scale survey, systematic mutation set). Whenever possible, allele information and additional details are provided. Click "Phenotype Details" to view all phenotype annotations and evidence for this locus as well as phenotypes it shares with other genes.
- Summary
- TOP3/YLR234W is a non-essential gene in reference strain S288C; null mutant has severe chromosome instability with increased recombination, chromosomal rearrangements, and chromosome loss; slow growth with morphological abnormalities including elongated cells and random budding; broad sensitivity to DNA-damaging agents and replication stress; absent respiratory growth; decreased telomere length and abnormal ER morphology; is haploproficient; overexpression causes S phase delay with methyl methanesulfonate; tetraploid derivative is temperature sensitive at 37°C
Classical Genetics
- null
- overexpression
- null
- budding pattern: abnormal
- cell shape: abnormal
- cell size: increased
- chemical compound accumulation: abnormal
- chemical compound accumulation: increased
- competitive fitness: decreased
- desiccation resistance: decreased
- endoplasmic reticulum morphology: abnormal
- haploproficient
- hyperosmotic stress resistance: decreased
- innate thermotolerance: decreased
- inviable
- metal resistance: decreased
- mutation frequency: increased
- nuclear morphology: abnormal
- resistance to chemicals: decreased
- respiratory growth: absent
- toxin resistance: decreased
- utilization of nitrogen source: decreased rate
- vegetative growth: decreased rate
- viable
- overexpression
Large-scale Survey
Interaction
Interaction annotations are curated by BioGRID and include physical or genetic interactions observed between at least two genes. An interaction annotation is composed of the interaction type, name of the interactor, assay type (e.g., Two-Hybrid), annotation type (e.g., manual or high-throughput), and a reference, as well as other experimental details. Click "Interaction Details" to view all interaction annotations and evidence for this locus, including an interaction visualization.
- Summary
- DNA Topoisomerase III interacts physically with proteins involved in DNA repair; TOP3 interacts genetically with genes involved in DNA repair
416 total interactions for 241 unique genes
Regulation
The number of putative Regulators (genes that regulate it) and Targets (genes it regulates) for the given locus, based on experimental evidence. This evidence includes data generated through high-throughput techniques. Click "Regulation Details" to view all regulation annotations, shared GO enrichment among regulation Targets, and a regulator/target diagram for the locus.
Expression
Expression data are derived from records contained in the Gene Expression Omnibus (GEO), and are first log2 transformed and normalized. Referenced datasets may contain one or more condition(s), and as a result there may be a greater number of conditions than datasets represented in a single clickable histogram bar. The histogram division at 0.0 separates the down-regulated (green) conditions and datasets from those that are up-regulated (red). Click "Expression Details" to view all expression annotations and details for this locus, including a visualization of genes that share a similar expression pattern.
Summary Paragraph
A summary of the locus, written by SGD Biocurators following a thorough review of the literature. Links to gene names and curated GO terms are included within the Summary Paragraphs.
Last Updated: 2026-09-04
All Curated Literature
All manually curated literature for the specified gene, shown as a count of references by year of publication followed by the most recent papers. Click "Literature Details" or "See all" to view all literature information for this locus, organized into topics according to their relevance to the gene (Primary Literature, Additional Literature, or Review).
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