Tel2p, a regulator of yeast telomeric length in vivo, binds to single-stranded telomeric DNA in vitro

Chromosoma. 1999 Sep;108(5):278-90. doi: 10.1007/s004120050379.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Composition
  • Base Sequence
  • DNA Methylation
  • DNA, Fungal / metabolism*
  • DNA, Single-Stranded / metabolism*
  • Dimethyl Sulfoxide / pharmacology
  • Fungal Proteins / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Telomere / metabolism*

Substances

  • DNA, Fungal
  • DNA, Single-Stranded
  • Fungal Proteins
  • Recombinant Fusion Proteins
  • Dimethyl Sulfoxide