TOP3/YLR234W Summary Help

Standard Name TOP3
Systematic Name YLR234W
Alias EDR1
Feature Type ORF, Verified
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 stimulated by RPA and Sgs1p-Top2p-Rmi1p; involved in telomere stability and regulation of mitotic recombination (1, 2, 3, 4, 5 and see Summary Paragraph)
Name Description TOPoisomerase
Chromosomal Location
ChrXII:609783 to 611753 | ORF Map | GBrowse
Genetic position: 163 cM
Gene Ontology Annotations All TOP3 GO evidence and references
  View Computational GO annotations for TOP3
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 7 genes
Classical genetics
Large-scale survey
198 total interaction(s) for 106 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 4
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 15
  • Biochemical Activity: 1
  • Co-fractionation: 3
  • Co-purification: 2
  • Reconstituted Complex: 2
  • Two-hybrid: 7

Genetic Interactions
  • Dosage Growth Defect: 2
  • Dosage Lethality: 1
  • Dosage Rescue: 2
  • Negative Genetic: 42
  • Phenotypic Enhancement: 9
  • Phenotypic Suppression: 4
  • Positive Genetic: 1
  • Synthetic Growth Defect: 35
  • Synthetic Lethality: 43
  • Synthetic Rescue: 23

Expression Summary
Length (a.a.) 656
Molecular Weight (Da) 74,370
Isoelectric Point (pI) 8.59
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXII:609783 to 611753 | ORF Map | GBrowse
Genetic position: 163 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1971 609783..611753 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000004224

Topoisomerases catalyze the interconversion between topological states of DNA by breaking and rejoining DNA strands. These changes in DNA topology are required during several cellular processes such as replication, transcription, recombination, and chromosome condensation (6). There are three classes of topoisomerases that are distinguished by substrate (IA, IB, II). Type I topoisomerases cleave one DNA strand, while Type II enzymes cleave a pair of complementary DNA strands (7). Type IA topoisomerases, encoded by TOP3 in yeast, relax only negatively supercoiled DNA, while type IB topoisomerases (TOP1 in yeast) relax both positively and negatively supercoiled DNA (7, 8, 9). Yeast topoisomerase II is encoded by the TOP2 gene (7).

TOP3 is homologous to E. coli topA and topB (4); homologs have also been identified in C. elegans (TOP-3, Y48C3A.P) and humans (TOP3, TOP3B) (10). top3 null mutants are viable but exhibit a variety of defects in cell cycle progression, recombination, transciption, mating, and sporulation. Recent work has elucidated the role of Top3p in sporulation; Top3 protein plays an essential role during meiotic recombination (11).

Last updated: 1999-11-09 Contact SGD

References cited on this page View Complete Literature Guide for TOP3
1) Kim RA, et al.  (1995) Effects of yeast DNA topoisomerase III on telomere structure. Proc Natl Acad Sci U S A 92(7):2667-71
2) Bennett RJ, et al.  (2000) Interaction between yeast sgs1 helicase and DNA topoisomerase III. J Biol Chem 275(35):26898-905
3) Bailis AM, et al.  (1992) Genome rearrangement in top3 mutants of Saccharomyces cerevisiae requires a functional RAD1 excision repair gene. Mol Cell Biol 12(11):4988-93
4) Kim RA and Wang JC  (1992) Identification of the yeast TOP3 gene product as a single strand-specific DNA topoisomerase. J Biol Chem 267(24):17178-85
5) Chang M, et al.  (2005) RMI1/NCE4, a suppressor of genome instability, encodes a member of the RecQ helicase/Topo III complex. EMBO J 24(11):2024-33
6) Berger JM  (1998) Structure of DNA topoisomerases. Biochim Biophys Acta 1400(1-3):3-18
7) Wang JC  (1996) DNA topoisomerases. Annu Rev Biochem 65:635-92
8) Thrash C, et al.  (1985) Cloning, characterization, and sequence of the yeast DNA topoisomerase I gene. Proc Natl Acad Sci U S A 82(13):4374-8
9) Goto T and Wang JC  (1985) Cloning of yeast TOP1, the gene encoding DNA topoisomerase I, and construction of mutants defective in both DNA topoisomerase I and DNA topoisomerase II. Proc Natl Acad Sci U S A 82(21):7178-82
10) Hodges PE, et al.  (1999) The Yeast Proteome Database (YPD): a model for the organization and presentation of genome-wide functional data. Nucleic Acids Res 27(1):69-73
11) Gangloff S, et al.  (1999) The essential role of yeast topoisomerase III in meiosis depends on recombination. EMBO J 18(6):1701-11