» Articles » PMID: 36299495

Heterogeneous Migration Routes of DNA Triplet Repeat Slip-outs

Overview
Specialty Biophysics
Date 2022 Oct 27
PMID 36299495
Authors
Affiliations
Soon will be listed here.
Abstract

It is unclear how the length of a repetitive DNA tract determines the onset and progression of repeat expansion diseases, but the dynamics of secondary DNA structures formed by repeat sequences are believed to play an important role. It was recently shown that three-way DNA junctions containing slip-out hairpins of CAG or CTG repeats and contiguous triplet repeats in the adjacent duplex displayed single-molecule FRET (smFRET) dynamics that were ascribed to both local conformational motions and longer-range branch migration. Here we explore these so-called "mobile" slip-out structures through a detailed kinetic analysis of smFRET trajectories and coarse-grained modeling. Despite the apparent structural simplicity, with six FRET states resolvable, most smFRET states displayed biexponential dwell-time distributions, attributed to structural heterogeneity and overlapping FRET states. Coarse-grained modeling for a (GAC) repeat slip-out included trajectories that corresponded to a complete round of branch migration; the structured free energy landscape between slippage events supports the dynamical complexity observed by smFRET. A hairpin slip-out with 40 CAG repeats, which is above the repeat length required for disease in several triplet repeat disorders, displayed smFRET dwell times that were on average double those of 3WJs with 10 repeats. The rate of secondary-structure rearrangement via branch migration, relative to particular DNA processing pathways, may be an important factor in the expansion of triplet repeat expansion diseases.

Citing Articles

Direct observation of subunit rotation during DNA strand exchange by serine recombinases.

Cadden G, Schloetel J, McKenzie G, Boocock M, Magennis S, Stark W Nat Commun. 2024; 15(1):10407.

PMID: 39613732 PMC: 11607074. DOI: 10.1038/s41467-024-54531-4.


Structural and Dynamical Properties of Nucleic Acid Hairpins Implicated in Trinucleotide Repeat Expansion Diseases.

Pan F, Xu P, Roland C, Sagui C, Weninger K Biomolecules. 2024; 14(10).

PMID: 39456210 PMC: 11505666. DOI: 10.3390/biom14101278.


A single CAA interrupt in a DNA three-way junction containing a CAG repeat hairpin results in parity-dependent trapping.

Cadden G, Wilken S, Magennis S Nucleic Acids Res. 2024; 52(15):9317-9327.

PMID: 39041420 PMC: 11347167. DOI: 10.1093/nar/gkae644.


How sequence alterations enhance the stability and delay expansion of DNA triplet repeat domains.

Volker J, Breslauer K QRB Discov. 2023; 4:e8.

PMID: 37965436 PMC: 10641665. DOI: 10.1017/qrd.2023.6.

References
1.
Snodin B, Randisi F, Mosayebi M, Sulc P, Schreck J, Romano F . Introducing improved structural properties and salt dependence into a coarse-grained model of DNA. J Chem Phys. 2015; 142(23):234901. DOI: 10.1063/1.4921957. View

2.
Castel A, Cleary J, Pearson C . Repeat instability as the basis for human diseases and as a potential target for therapy. Nat Rev Mol Cell Biol. 2010; 11(3):165-70. DOI: 10.1038/nrm2854. View

3.
Lerner E, Barth A, Hendrix J, Ambrose B, Birkedal V, Blanchard S . FRET-based dynamic structural biology: Challenges, perspectives and an appeal for open-science practices. Elife. 2021; 10. PMC: 8007216. DOI: 10.7554/eLife.60416. View

4.
Kaplan S, Itzkovitz S, Shapiro E . A universal mechanism ties genotype to phenotype in trinucleotide diseases. PLoS Comput Biol. 2007; 3(11):e235. PMC: 2082501. DOI: 10.1371/journal.pcbi.0030235. View

5.
Kacher R, Lejeune F, Noel S, Cazeneuve C, Brice A, Humbert S . Propensity for somatic expansion increases over the course of life in Huntington disease. Elife. 2021; 10. PMC: 8118653. DOI: 10.7554/eLife.64674. View