A Novel G-Quadruplex Binding Protein in Yeast-Slx9

Molecules. 2019 May 7;24(9):1774. doi: 10.3390/molecules24091774.


G-quadruplex (G4) structures are highly stable four-stranded DNA and RNA secondary structures held together by non-canonical guanine base pairs. G4 sequence motifs are enriched at specific sites in eukaryotic genomes, suggesting regulatory functions of G4 structures during different biological processes. Considering the high thermodynamic stability of G4 structures, various proteins are necessary for G4 structure formation and unwinding. In a yeast one-hybrid screen, we identified Slx9 as a novel G4-binding protein. We confirmed that Slx9 binds to G4 DNA structures in vitro. Despite these findings, Slx9 binds only insignificantly to G-rich/G4 regions in Saccharomyces cerevisiae as demonstrated by genome-wide ChIP-seq analysis. However, Slx9 binding to G4s is significantly increased in the absence of Sgs1, a RecQ helicase that regulates G4 structures. Different genetic and molecular analyses allowed us to propose a model in which Slx9 recognizes and protects stabilized G4 structures in vivo.

Keywords: G-quadruplex formation; RecQ helicase; S. cerevisiae; genome stability; protein–DNA interaction.

MeSH terms

  • DNA Helicases / chemistry
  • DNA Helicases / genetics
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / genetics
  • G-Quadruplexes*
  • Genome / genetics
  • Nucleic Acid Conformation
  • Protein Binding
  • RecQ Helicases / chemistry
  • RecQ Helicases / genetics
  • Ribosomal Proteins / chemistry
  • Ribosomal Proteins / genetics*
  • Saccharomyces cerevisiae / chemistry
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics*
  • Thermodynamics


  • DNA-Binding Proteins
  • Ribosomal Proteins
  • SLX9 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • SGS1 protein, S cerevisiae
  • DNA Helicases
  • RecQ Helicases