Telomere end-binding proteins control the formation of G-quadruplex DNA structures in vivo.
Telomere end-binding proteins (TEBPs) bind to the guanine-rich overhang (G-overhang) of telomeres. Although the DNA binding properties of TEBPs have been investigated in vitro, little is known about their functions in vivo. Here we use RNA interference to explore in vivo functions of two ciliate TEBPs, TEBPalpha and TEBPbeta. Silencing the expression of genes encoding both TEBPs shows that they cooperate to control the formation of an antiparallel guanine quadruplex (G-quadruplex) DNA structure at telomeres in vivo. This function seems to depend on the role of TEBPalpha in attaching telomeres in the nucleus and in recruiting TEBPbeta to these sites. In vitro DNA binding and footprinting studies confirm the in vivo observations and highlight the role of the C terminus of TEBPbeta in G-quadruplex formation. We have also found that G-quadruplex formation in vivo is regulated by the cell cycle-dependent phosphorylation of TEBPbeta.
Paeschke
Katrin
K
Institute of Cell Biology, University Witten/Herdecke, Stockumer Strasse 10, 58453 Witten, Germany.
Simonsson
Tomas
T
Postberg
Jan
J
Rhodes
Daniela
D
Lipps
Hans Joachim
HJ
D000818:Animals; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D016798:Ciliophora / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D054856:G-Quadruplexes; D006147:Guanine / Q000737:chemistry*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D016615:Telomere / Q000737:chemistry / Q000378:metabolism*; D034501:Telomere-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
D015800:Protozoan Proteins; D034501:Telomere-Binding Proteins; D006147:Guanine; D004247:DNA