title: Identification of TTAGGG-binding proteins in Neurospora crassa, a fungus with vertebrate-like telomere repeats.
abstract: BACKGROUND
  To date, telomere research in fungi has mainly focused on Saccharomyces cerevisiae and Schizosaccharomyces pombe, despite the fact that both yeasts have degenerated telomeric repeats in contrast to the canonical TTAGGG motif found in vertebrates and also several other fungi.
  
  
  RESULTS
  Using label-free quantitative proteomics, we here investigate the telosome of Neurospora crassa, a fungus with canonical telomeric repeats. We show that at least six of the candidates detected in our screen are direct TTAGGG-repeat binding proteins. While three of the direct interactors (NCU03416 [ncTbf1], NCU01991 [ncTbf2] and NCU02182 [ncTay1]) feature the known myb/homeobox DNA interaction domain also found in the vertebrate telomeric factors, we additionally show that a zinc-finger protein (NCU07846) and two proteins without any annotated DNA-binding domain (NCU02644 and NCU05718) are also direct double-strand TTAGGG binders. We further find two single-strand binders (NCU02404 [ncGbp2] and NCU07735 [ncTcg1]).
  
  
  CONCLUSIONS
  By quantitative label-free interactomics we identify TTAGGG-binding proteins in Neurospora crassa, suggesting candidates for telomeric factors that are supported by phylogenomic comparison with yeast species. Intriguingly, homologs in yeast species with degenerated telomeric repeats are also TTAGGG-binding proteins, e.g. in S. cerevisiae Tbf1 recognizes the TTAGGG motif found in its subtelomeres. However, there is also a subset of proteins that is not conserved. While a rudimentary core TTAGGG-recognition machinery may be conserved across yeast species, our data suggests Neurospora as an emerging model organism with unique features.
authors.affiliation: Quantitative Proteomics, Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128, Mainz, Germany.
authors.forename: Núria
authors.initials: N
authors.lastname: Casas-Vila
authors.affiliation: Quantitative Proteomics, Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128, Mainz, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Scheibe
authors.affiliation: Quantitative Proteomics, Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128, Mainz, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Freiwald
authors.affiliation: Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, 117599, Singapore, Singapore.
authors.forename: Dennis
authors.initials: D
authors.lastname: Kappei
authors.affiliation: Quantitative Proteomics, Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128, Mainz, Germany. f.butter@imb.de.
authors.forename: Falk
authors.initials: F
authors.lastname: Butter
mesh_terms: D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000378:metabolism*; D009492:Neurospora crassa / Q000235:genetics / Q000378:metabolism*; D059372:Nucleotide Motifs; D040901:Proteomics; D012091:Repetitive Sequences, Nucleic Acid; D016615:Telomere / Q000235:genetics*; D014714:Vertebrates / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins