Saccharomyces cerevisiae RAP1 binds to telomeric sequences with spatial flexibility.
A wide divergence has been detected in the telomeric sequences among budding yeast species. Despite their length and homogeneity differences, all these yeast telomeric sequences show a conserved core which closely matches the consensus RAP1-binding sequence. We demonstrate that the RAP1 protein binds this sequence core, without involving the diverged sequences outside the core. In Saccharomyces castellii and Saccharomyces dairensis specific classes of interspersed variant repeats are present. We show here that a RAP1-binding site is formed in these species by connecting two consecutive 8 bp telomeric repeats. DNase I footprint analyses specify the binding site as the 13 bp sequence CTGGGTGTCTGGG. The RAP1 protein also binds the variant repeats, although with a lowered affinity. However, a split footprint is produced when RAP1 binds a variant repeat where the two half-sites of the binding site are separated by an additional 6 nt. This is probably caused by the intervening sequence looping out of the RAP1-DNA complex. We suggest that the bipartite subdomain structure of the RAP1 protein allows it to remodel telomeric chromatin, a feature which may be of great relevance for telomeric chromatin assembly and structure in vivo.
Wahlin
J
J
Department of Molecular Genetics, Lund University, Sölvegatan 29, S-223 62 Lund, Sweden.
Cohn
M
M
D001483:Base Sequence; D001665:Binding Sites; D016384:Consensus Sequence; D018983:DNA Footprinting; D003850:Deoxyribonuclease I; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000378:metabolism; D012440:Saccharomyces / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D016615:Telomere / Q000737:chemistry / Q000378:metabolism*; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*
D011994:Recombinant Proteins; D003850:Deoxyribonuclease I; D020827:rap1 GTP-Binding Proteins