Interrogating accessibility of telomeric sequences with FRET-PAINT: evidence for length-dependent telomere compaction.
Nucleic Acids Res
; 49(6): 3371-3380, 2021 04 06.
Article
em En
| MEDLINE
| ID: mdl-33693934
ABSTRACT
Single-stranded telomeric overhangs are â¼200 nucleotides long and can form tandem G-quadruplex (GQ) structures, which reduce their accessibility to nucleases and proteins that activate DNA damage response. Whether these tandem GQs further stack to form compact superstructures, which may provide better protection for longer telomeres, is not known. We report single-molecule measurements where the accessibility of 24-144 nucleotide long human telomeric DNA molecules is interrogated by a short PNA molecule that is complementary to a single GGGTTA repeat, as implemented in the FRET-PAINT method. Binding of the PNA strand to available GGGTTA sequences results in discrete FRET bursts which were analyzed in terms of their dwell times, binding frequencies, and topographic distributions. The binding frequencies were greater for binding to intermediate regions of telomeric DNA compared to 3'- or 5'-ends, suggesting these regions are more accessible. Significantly, the binding frequency per telomeric repeat monotonically decreased with increasing telomere length. These results are consistent with telomeres forming more compact structures at longer lengths, reducing accessibility of these critical genomic sites.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Telômero
Limite:
Humans
Idioma:
En
Revista:
Nucleic Acids Res
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Estados Unidos