Poster abstracts

Poster number 13 submitted by Hamza Balci

Protection of Long Telomeric Overhangs by Shelterin

Hamza Balci (Physics Department, Kent State University), Sajad Shiekh (Physics Department, Kent State University), Amanda Jack (University of California, Berkeley), Sineth Kodikara (Physics Department, Kent State University), Janan Alfehaid (Physics Department, Kent State University), Ahmet Yildiz (University of California, Berkeley)

Abstract:
We present single molecule fluorescence (including FRET, FRET-PAINT, and PIFE) studies that probe the folding patterns and accessibilities of telomeric overhangs of physiologically relevant lengths (up to 28 GGGTTA repeats). In particular, we investigate the impact of shelterin complex and POT1 on the accessibility and protection of these otherwise vulnerable genomic regions. In addition to length-dependent periodic accessibility patterns, we present the impact of POT1 and Shelterin on these accessibility patterns. On average POT1 reduces the telomeric accessibility by ~2.5-fold and Shelterin by ~5-fold. Our studies also illustrate the junction between single and double stranded telomeres to be highly accessible in the absence of shelterin. We present recent work in which we focused on this junction region to understand the minimum requirements to attain effective protection by Shelterin or POT1, and the impact of 5-phosphorylation and sequence variations on protection of this region.

References:
1- Sajad Shiekh, …, Ahmet Yildiz, Hamza Balci, "Protection of the Telomeric Junction by the Shelterin Complex", JACS (2024), DOI:10.1021/jacs.4c08649
2- Sineth G. Kodikara, …, Hamza Balci, "Detecting Secondary Structure Formation with FRET-PAINT", RSC-Analyst (2023) DOI: 10.1039/d3an01118f
3- Sajad Shiekh, Sineth G. Kodikara, Hamza Balci, "Structure, Topology, and Stability of Multiple G-quadruplexes in Long Telomeric Overhangs" Journal of Molecular Biology (2023)
DOI: 10.1016/j.jmb.2023.168205
4- Sajad Shiekh, …, Ahmet Yildiz, Hamza Balci , "Shelterin reduces the accessibility of telomeric overhangs", Nuc. Acids Res. (2022). DOI: 10.1093/nar/gkac1176
5- Sajad Shiekh, …, Hamza Balci, "Emerging Accessibility Patterns in Long Telomeric Overhangs", PNAS (2022), DOI: 10.1073/pnas.2202317119

Keywords: Telomere, G-quadruplex, Shelterin