Role of folding kinetics of secondary structures in telomeric G-overhangs in the regulation of telomere maintenance inSaccharomyces cerevisiae

Warning

This publication doesn't include Faculty of Sports Studies. It includes Central European Institute of Technology. Official publication website can be found on muni.cz.

Authors	JURIKOVA K. GAJARSKÝ Martin HAJIKAZEMI M. NOSEK J. PROCHAZKOVA K. PAESCHKE K. TRANTÍREK Lukáš TOMASKA L.
Year of publication	2020
Type	Article in Periodical
Magazine / Source	Journal of Biological Chemistry
MU Faculty or unit	Central European Institute of Technology
Citation
Web	https://www.jbc.org/article/S0021-9258(17)50320-8/pdf
Doi	http://dx.doi.org/10.1074/jbc.RA120.012914
Keywords	telomere; telomerase; Saccharomyces cerevisiae; cell cycle; Cdc13; G-hairpin; G-quadruplex; folding kinetics
Description	The ends of eukaryotic chromosomes typically contain a 3? ssDNA G-rich protrusion (G-overhang). This overhang must be protected against detrimental activities of nucleases and of the DNA damage response machinery and participates in the regulation of telomerase, a ribonucleoprotein complex that maintains telomere integrity. These functions are mediated by DNA-binding proteins, such as Cdc13 inSaccharomyces cerevisiae, and the propensity of G-rich sequences to form various non-B DNA structures. Using CD and NMR spectroscopies, we show here that G-overhangs ofS. cerevisiaeform distinct Hoogsteen pairing?based secondary structures, depending on their length. Whereas short telomeric oligonucleotides form a G-hairpin, their longer counterparts form parallel and/or antiparallel G-quadruplexes (G4s). Regardless of their topologies, non-B DNA structures exhibited impaired binding to Cdc13in vitroas demonstrated by electrophoretic mobility shift assays. Importantly, whereas G4 structures formed relatively quickly, G-hairpins folded extremely slowly, indicating that short G-overhangs, which are typical for most of the cell cycle, are present predominantly as single-stranded oligonucleotides and are suitable substrates for Cdc13. Using ChIP, we show that the occurrence of G4 structures peaks at the late S phase, thus correlating with the accumulation of long G-overhangs. We present a model of how time- and length-dependent formation of non-B DNA structures at chromosomal termini participates in telomere maintenance.
Related projects:	CEITEC 2020 Polymorfní G-quadruplexy v promotorových oblastech genů Atomically resolved in vivo NMR spectroscopy as a novel tool for biological testing of therapeutically important genomic non-canonical DNA targets and their interactions with drugs in phenotypically diversified cancer cells.