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Cadden GM, Wilken SJ, Magennis SW. A single CAA interrupt in a DNA three-way junction containing a CAG repeat hairpin results in parity-dependent trapping. Nucleic Acids Res 2024:gkae644. [PMID: 39041420 DOI: 10.1093/nar/gkae644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 07/04/2024] [Accepted: 07/14/2024] [Indexed: 07/24/2024] Open
Abstract
An increasing number of human disorders are attributed to genomic expansions of short tandem repeats (STRs). Secondary DNA structures formed by STRs are believed to play an important role in expansion, while the presence of nucleotide interruptions within the pure repeat sequence is known to delay the onset and progression of disease. We have used two single-molecule fluorescence techniques to analyse the structure and dynamics of DNA three-way junctions (3WJs) containing CAG repeat hairpin slipouts, with and without a single CAA interrupt. For a 3WJ with a (CAG)10 slipout, the CAA interrupt is preferentially located in the hairpin loop, and the branch migration dynamics are 4-fold slower than for the 3WJ with a pure (CAG)10, and 3-fold slower than a 3WJ with a pure (CAG)40 repeat. The (CAG)11 3WJ with CAA interrupt adopts a conformation that places the interrupt in or near the hairpin loop, with similar dynamics to the pure (CAG)10 and (CAG)11 3WJs. We have shown that changing a single nucleotide (G to A) in a pure repeat can have a large impact on 3WJ structure and dynamics, which may be important for the protective role of interrupts in repeat expansion diseases.
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Affiliation(s)
- Gillian M Cadden
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, UK
| | - Svea J Wilken
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, UK
| | - Steven W Magennis
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, UK
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Drobotenko MI, Lyasota OM, Hernandez-Caceres JL, Labrada RR, Svidlov AA, Dorohova АA, Baryshev MG, Nechipurenko YD, Pérez LV, Dzhimak SS. Abnormal open states patterns in the ATXN2 DNA sequence depends on the CAG repeats length. Int J Biol Macromol 2024; 276:133849. [PMID: 39004246 DOI: 10.1016/j.ijbiomac.2024.133849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 05/04/2024] [Accepted: 07/11/2024] [Indexed: 07/16/2024]
Abstract
Hereditary ataxias are one of the «anticipation diseases» types. Spinocerebral ataxia type 2 occurs when the number of CAG repeats in the coding region of the ATXN2 gene exceeds 34 or more. In healthy people, the CAG repeat region in the ATXN2 gene usually consists of 22-23 CAG trinucleotides. Mutations that increase the length of CAG repeats can cause severe neurodegenerative and neuromuscular disorders known as trinucleotide repeat expansion diseases. The mechanisms causing such diseases are associated with non-canonical configurations that can be formed in the CAG repeat region during replication, transcription or repair. This makes it relevant to study the zones of open states that arise in the region of CAG repeats under torque. The purpose of this work is to study, using mathematical modeling, zones of open states in the region of CAG repeats of the ATXN2 gene, caused by torque. It has been established that the torque effect on the 1st exon of the ATXN2 gene, in addition to the formation of open states in the promoter region, can lead to the formation of additional various sizes open states zones in the CAG repeats region. Moreover, the frequency of additional large zones genesis increases with increasing number of CAG repeats. The inverse of this frequency correlates with the dependence of the disease onset average age on the CAG repeats length. The obtained results will allow us to get closer to understanding the genetic mechanisms that cause trinucleotide repeat diseases.
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Affiliation(s)
- Mikhail I Drobotenko
- Department of Radiophysics and Nanothechnology, Kuban State University, 350040 Krasnodar, Russian Federation
| | - Oksana M Lyasota
- Laboratory of Problems of Stable Isotope Spreading in Living Systems, Southern Scientific Center of the Russian Academy of Sciences, 344006 Rostov-on-Don, Russian Federation
| | | | | | - Alexandr A Svidlov
- Laboratory of Problems of Stable Isotope Spreading in Living Systems, Southern Scientific Center of the Russian Academy of Sciences, 344006 Rostov-on-Don, Russian Federation
| | - Аnna A Dorohova
- Department of Radiophysics and Nanothechnology, Kuban State University, 350040 Krasnodar, Russian Federation; Laboratory of Problems of Stable Isotope Spreading in Living Systems, Southern Scientific Center of the Russian Academy of Sciences, 344006 Rostov-on-Don, Russian Federation
| | - Mikhail G Baryshev
- Laboratory of Problems of Stable Isotope Spreading in Living Systems, Southern Scientific Center of the Russian Academy of Sciences, 344006 Rostov-on-Don, Russian Federation
| | - Yury D Nechipurenko
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russian Federation
| | | | - Stepan S Dzhimak
- Department of Radiophysics and Nanothechnology, Kuban State University, 350040 Krasnodar, Russian Federation; Laboratory of Problems of Stable Isotope Spreading in Living Systems, Southern Scientific Center of the Russian Academy of Sciences, 344006 Rostov-on-Don, Russian Federation.
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Wan L, He A, Li J, Guo P, Han D. High-Resolution NMR Structures of Intrastrand Hairpins Formed by CTG Trinucleotide Repeats. ACS Chem Neurosci 2024; 15:868-876. [PMID: 38319692 DOI: 10.1021/acschemneuro.3c00769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024] Open
Abstract
The CAG and CTG trinucleotide repeat expansions cause more than 10 human neurodegenerative diseases. Intrastrand hairpins formed by trinucleotide repeats contribute to repeat expansions, establishing them as potential drug targets. High-resolution structural determination of CAG and CTG hairpins poses as a long-standing goal to aid drug development, yet it has not been realized due to the intrinsic conformational flexibility of repetitive sequences. We herein investigate the solution structures of CTG hairpins using nuclear magnetic resonance (NMR) spectroscopy and found that four CTG repeats with a clamping G-C base pair was able to form a stable hairpin structure. We determine the first solution NMR structure of dG(CTG)4C hairpin and decipher a type I folding geometry of the TGCT tetraloop, wherein the two thymine residues form a T·T loop-closing base pair and the first three loop residues continuously stack. We further reveal that the CTG hairpin can be bound and stabilized by a small-molecule ligand, and the binding interferes with replication of a DNA template containing CTG repeats. Our determined high-resolution structures lay an important foundation for studying molecular interactions between native CTG hairpins and ligands, and benefit drug development for trinucleotide repeat expansion diseases.
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Affiliation(s)
- Liqi Wan
- Institute of Molecular Medicine (IMM), Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
- Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Axin He
- Institute of Molecular Medicine (IMM), Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
- Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Jinxing Li
- ReviR Therapeutics, Shenzhen Bay Hi-Tech Ecological Park, Nanshan District, Shenzhen, Guangdong 518067, China
| | - Pei Guo
- Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Da Han
- Institute of Molecular Medicine (IMM), Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
- Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
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Fakharzadeh A, Qu J, Pan F, Sagui C, Roland C. Structure and Dynamics of DNA and RNA Double Helices Formed by d(CTG), d(GTC), r(CUG), and r(GUC) Trinucleotide Repeats and Associated DNA-RNA Hybrids. J Phys Chem B 2023; 127:7907-7924. [PMID: 37681731 PMCID: PMC10519205 DOI: 10.1021/acs.jpcb.3c03538] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/11/2023] [Indexed: 09/09/2023]
Abstract
Myotonic dystrophy type 1 is the most frequent form of muscular dystrophy in adults caused by an abnormal expansion of the CTG trinucleotide. Both the expanded DNA and the expanded CUG RNA transcript can fold into hairpins. Co-transcriptional formation of stable RNA·DNA hybrids can also enhance the instability of repeat tracts. We performed molecular dynamics simulations of homoduplexes associated with the disease, d(CTG)n and r(CUG)n, and their corresponding r(CAG)n:d(CTG)n and r(CUG)n:d(CAG)n hybrids that can form under bidirectional transcription and of non-pathological d(GTC)n and d(GUC)n homoduplexes. We characterized their conformations, stability, and dynamics and found that the U·U and T·T mismatches are dynamic, favoring anti-anti conformations inside the helical core, followed by anti-syn and syn-syn conformations. For DNA, the secondary minima in the non-expanding d(GTC)n helices are deeper, wider, and longer-lived than those in d(CTG)n, which constitutes another biophysical factor further differentiating the expanding and non-expanding sequences. The hybrid helices are closer to A-RNA, with the A-T and A-U pairs forming two stable Watson-Crick hydrogen bonds. The neutralizing ion distribution around the non-canonical pairs is also described.
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Affiliation(s)
- Ashkan Fakharzadeh
- Department
of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
| | - Jing Qu
- Department
of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
| | - Feng Pan
- Department
of Statistics, Florida State University, Tallahassee, Florida 32306, USA
| | - Celeste Sagui
- Department
of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
| | - Christopher Roland
- Department
of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
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