title: The yeast telomere-binding protein RAP1 binds to and promotes the formation of DNA quadruplexes in telomeric DNA.
abstract: The protein RAP1 is essential for the maintenance of the telomeres of Saccharomyces cerevisiae and binds in vitro to multiple sites found within the TG1-3 telomeric repeats. We show here that, in addition to its known binding activity for double-stranded DNA, RAP1 binds sequence-specifically to the GT-strands. This indicates that RAP1 is the protein that binds to the telomeric terminal GT-tails. Furthermore, we have found that RAP1 binds to and promotes the formation of G-tetrads, i.e. DNA quadruplexes, in GT-strand oligonucleotides at nanomolar concentrations. The formation of DNA quadruplexes appears to involve the intermolecular association of GT-strands. The minimal DNA-binding domain of RAP1 (DBD) binds only to double-stranded DNA, so that the novel DNA-binding activity we have found involves regions of the protein located outside of the DBD. The finding that a telomeric protein promotes the formation of G-tetrads argues for the use of DNA quadruplexes in telomere association.
authors.affiliation: MRC Laboratory of Molecular Biology, Cambridge, UK.
authors.forename: R
authors.initials: R
authors.lastname: Giraldo
authors.forename: D
authors.initials: D
authors.lastname: Rhodes
mesh_terms: D001483:Base Sequence; D004271:DNA, Fungal / Q000378:metabolism* / Q000648:ultrastructure; D005656:Fungal Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006147:Guanine / Q000031:analogs & derivatives; D008745:Methylation; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000378:metabolism; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism*; D020668:rap GTP-Binding Proteins
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D009841:Oligonucleotides; D006147:Guanine; C008450:7-methylguanine; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins