SGS1/YMR190C Summary Help

Standard Name SGS1 1
Systematic Name YMR190C
Feature Type ORF, Verified
Description RecQ family nucleolar DNA helicase; role in genome integrity maintenance; regulates chromosome synapsis and meiotic joint molecule/crossover formation; stimulates DNA catenation/decatenation activity of Top3p; potential repressor of a subset of rapamycin responsive genes; rapidly lost in response to rapamycin in Rrd1p-dependent manner; similar to human BLM and WRN proteins implicated in Bloom and Werner syndromes; forms nuclear foci upon DNA replication stress (2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and see Summary Paragraph)
Name Description Slow Growth Suppressor
Chromosomal Location
ChrXIII:645258 to 640915 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 115.6 cM
Gene Ontology Annotations All SGS1 GO evidence and references
  View Computational GO annotations for SGS1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 5 genes
Classical genetics
Large-scale survey
1082 total interaction(s) for 441 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 5
  • Affinity Capture-Western: 25
  • Biochemical Activity: 5
  • Co-fractionation: 2
  • Co-localization: 1
  • Protein-peptide: 1
  • Reconstituted Complex: 3
  • Two-hybrid: 22

Genetic Interactions
  • Dosage Growth Defect: 3
  • Dosage Lethality: 1
  • Dosage Rescue: 11
  • Negative Genetic: 117
  • Phenotypic Enhancement: 105
  • Phenotypic Suppression: 47
  • Positive Genetic: 20
  • Synthetic Growth Defect: 228
  • Synthetic Lethality: 410
  • Synthetic Rescue: 76

Expression Summary
Length (a.a.) 1,447
Molecular Weight (Da) 163,836
Isoelectric Point (pI) 6.27
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXIII:645258 to 640915 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 115.6 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..4344 645258..640915 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 SGDIDS000004802

SGS1 encodes a helicase with similarity to E. coli RecQ and human BLM and WRN helicases (12). Mutations in BLM are implicated in the cancer-prone Bloom's Syndrome, and mutations in WRN cause the premature-aging Werner's Syndrome (12). SGS1 was identified in a screen for suppressors of the slow growth phenotype of top3 mutants, and Sgs1p has been shown to interact with the topoisomerase Top3p (13). Sgs1p appears to be involved in the maintenance of genome stability and the suppression of illegitimate recombination; sgs1 null mutants show mitotic hyperrecombination and elevated levels of chromosome missegregation (14, 15, 16). Sgs1p has been localized to the nucleolus, and is needed to maintain the integrity of rDNA repeats (2). Sgs1p shows ATPase activity and unwinds duplex DNA; it preferentially binds to branched DNA substrates and has a 3' to 5' polarity of unwinding (17, 18).

Last updated: 2000-03-10 Contact SGD

References cited on this page View Complete Literature Guide for SGS1
1) Sternglanz, R.  (1993) Personal Communication, Mortimer Map Edition 12
2) Sun H, et al.  (1999) The Saccharomyces cerevisiae Sgs1 helicase efficiently unwinds G-G paired DNAs. Nucleic Acids Res 27(9):1978-84
3) Huber MD, et al.  (2002) G4 DNA unwinding by BLM and Sgs1p: substrate specificity and substrate-specific inhibition. Nucleic Acids Res 30(18):3954-61
4) Versini G, et al.  (2003) The yeast Sgs1 helicase is differentially required for genomic and ribosomal DNA replication. EMBO J 22(8):1939-49
5) Rockmill B, et al.  (2003) The Sgs1 helicase regulates chromosome synapsis and meiotic crossing over. Curr Biol 13(22):1954-62
6) Oh SD, et al.  (2008) RecQ helicase, Sgs1, and XPF family endonuclease, Mus81-Mms4, resolve aberrant joint molecules during meiotic recombination. Mol Cell 31(3):324-36
7) Jessop L and Lichten M  (2008) Mus81/Mms4 endonuclease and Sgs1 helicase collaborate to ensure proper recombination intermediate metabolism during meiosis. Mol Cell 31(3):313-23
8) Marrakchi R, et al.  (2011) The isomerase Rrd1 mediates rapid loss of the Sgs1 helicase in response to rapamycin. Biochem Cell Biol 89(3):332-40
9) Tkach JM, et al.  (2012) Dissecting DNA damage response pathways by analysing protein localization and abundance changes during DNA replication stress. Nat Cell Biol 14(9):966-76
10) Cejka P, et al.  (2012) Decatenation of DNA by the S. cerevisiae Sgs1-Top3-Rmi1 and RPA complex: a mechanism for disentangling chromosomes. Mol Cell 47(6):886-96
11) Marrakchi R, et al.  (2013) A functional autophagy pathway is required for rapamycin-induced degradation of the Sgs1 helicase in Saccharomyces cerevisiae. Biochem Cell Biol 91(5):123-30
12) Kusano K, et al.  (1999) Evolution of the RECQ family of helicases: A drosophila homolog, Dmblm, is similar to the human bloom syndrome gene. Genetics 151(3):1027-39
13) Gangloff S, et al.  (1994) The yeast type I topoisomerase Top3 interacts with Sgs1, a DNA helicase homolog: a potential eukaryotic reverse gyrase. Mol Cell Biol 14(12):8391-8
14) Watt PM, et al.  (1995) Sgs1: a eukaryotic homolog of E. coli RecQ that interacts with topoisomerase II in vivo and is required for faithful chromosome segregation. Cell 81(2):253-60
15) Watt PM, et al.  (1996) SGS1, a homologue of the Bloom's and Werner's syndrome genes, is required for maintenance of genome stability in Saccharomyces cerevisiae. Genetics 144(3):935-45
16) Yamagata K, et al.  (1998) Bloom's and Werner's syndrome genes suppress hyperrecombination in yeast sgs1 mutant: implication for genomic instability in human diseases. Proc Natl Acad Sci U S A 95(15):8733-8
17) Bennett RJ, et al.  (1998) Purification and characterization of the Sgs1 DNA helicase activity of Saccharomyces cerevisiae. J Biol Chem 273(16):9644-50
18) Bennett RJ, et al.  (1999) Binding specificity determines polarity of DNA unwinding by the Sgs1 protein of S. cerevisiae. J Mol Biol 289(2):235-48