Tel2p, a regulator of yeast telomeric length in vivo, binds to single-stranded telomeric DNA in vitro.
The telomeres of the yeast Saccharomyces cerevisiae consist of a duplex region of TG(1-3) repeats that acquire a single-stranded 3' extension of the TG(1-3) strand at the end of S-phase. The length of these repeats is kept within a defined range by regulators such as the TEL2-encoded protein (Tel2p). Here we show that Tel2p can specifically bind to single-stranded TG(1-3). Tel2p binding produced several shifted bands; however, only the slowest migrating band contained Tel2p. Methylation protection and interference experiments as well as gel shift experiments using inosine-containing probes indicated that the faster migrating bands resulted from Tel2p-mediated formation of DNA secondary structures held together by G-G interactions. Tel2p bound to single-stranded substrates that were at least 19 bases in length and contained 14 bases of TG(1-3), and also to double-stranded/single-stranded hybrid substrates with a 3' TG(1-3) overhang. Tel2p binding to a hybrid substrate with a 24 base single-stranded TG(1-3) extension also produced a band characteristic of G-G-mediated secondary structures. These data suggest that Tel2p could regulate telomeric length by binding to the 3' single-stranded TG(1-3) extension present at yeast telomeres.
Kota
R S
RS
The Lerner Research Institute, Cleveland Clinic Foundation, Department of Molecular Biology, NC 20, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Runge
K W
KW
D001482:Base Composition; D001483:Base Sequence; D019175:DNA Methylation; D004271:DNA, Fungal / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D005656:Fungal Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism*
D004271:DNA, Fungal; D004277:DNA, Single-Stranded; D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D004121:Dimethyl Sulfoxide