Poster abstracts
Poster number 82 submitted by Sineth G Kodikara
Protection of the Telomeric Junction by the Shelterin Complex
Sineth G Kodikara (Department of Physics, Kent State University), Sajad Shiekh (Department of Physics, Kent State University), Amanda Jack (Department of Molecular and Cell Biology, University of California), Janan Alfehaid (Department of Physics, Kent State University), Ahmet Yildiz (Department of Molecular and Cell Biology, University of California), Hamza Balci (Department of Physics, Kent State University)
Abstract:
Shelterin plays a vital role in preventing inappropriate DNA damage repair mechanisms at telomeres. The junction between double-stranded telomeric regions (dsTEL) and the single-stranded telomeric overhang (ssTEL) represents the most accessible part of telomeric DNA. Shelterin comprises proteins that bind to both dsTEL and ssTEL, allowing it to protect this junction by bridging the ssTEL and dsTEL segments. To explore this function, we examined shelterin binding to telomeric DNA substrates with varying lengths of ssTEL and dsTEL and assessed its effect on telomere accessibility using single-molecule fluorescence microscopy in vitro. Our findings reveal that the first dsTEL repeat closest to the junction serves as the primary binding site for shelterin to form the bridge. Shelterin requires at least two ssTEL repeats for binding, whereas the POT1 subunit, which specifically binds ssTEL, necessitates longer ssTEL tracts for stable association and effective protection of the junction. The protective function of POT1 at the junction is significantly improved by the presence of a 5′-phosphate group. Overall, our results demonstrate that shelterin enhances the binding stability of POT1 to ssTEL and provides superior protection by bridging single- and double-stranded telomeric regions, compared to POT1 alone.
Keywords: Telomere , Shelterin, FRET-PAINT