Beyond structure : methylation fine-tunes stability and folding kinetics of bcl2Mid G-quadruplex

Medved, Nataša (avtor), Cevec, Mirko (avtor), Javornik, Uroš (avtor), Lah, Jurij (avtor), Hadži, San (avtor), Plavec, Janez (avtor)

Cytosine methylation, a key epigenetic modification in the regulation of gene expression, raises intriguing questions about its role in the formation and thermodynamic stability of G-quadruplex (G4) structures. We investigated the impact of the 5-methylcytosine residue (C$^m$) on the well-characterized bcl2Mid G4 structure that forms in a GC-rich region of the B-cell lymphoma 2 (BCL2) gene promoter, which influences its expression. Using solution-state NMR and biophysical techniques, we discovered an unexpected sequence-specific effect of C$^m$ on the folding kinetics of bcl2Mid G4. Specifically, substituting cytosine at position C6 with C6$^m$ slows down G4 folding kinetics and influences the equilibrium between major and minor structures in the presence of K$^+$ ions. Notably, the increased population of the minor structure enabled the characterization of its previously unidentified topology. Additionally, the presence of a single C$^m$ residue induces local structural rearrangements in the major G4 structure and decreases its thermodynamic stability. Furthermore, we found that the zinc finger 3 motif of the Sp1 transcription factor preferentially binds to the minor G4 structure. These results suggest that C$^m$ not only influences G4 polymorphism but may also regulate interactions with transcription factors, potentially affecting the regulation of gene expression.

• Jezik: Angleški jezik
• Ključne besede: differential scanning calorimetry, DNA, methylation, G-quadruplexes, kinetics, NMR spectroscopy
• Vrsta gradiva: Članek v reviji
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Status publikacije: Objavljeno
• Različica publikacije: Objavljena publikacija
• Leto izida: 2025
• Št. strani: 11 str.
• Številčenje: Vol. 64, iss. 24, art. e202507544
• PID: 20.500.12556/RUL-176688
• UDK: 577
• ISSN pri članku: 1521-3773
• DOI: 10.1002/anie.202507544
• COBISS.SI-ID: 242792707
• Datum objave v RUL: 09.12.2025

Gradivo je del revije

• Naslov: Angewandte Chemie : international edition
• Skrajšan naslov: Angew. Chem.
• Založnik: Wiley
• ISSN: 1521-3773
• COBISS.SI-ID: 21810181

Licence

• Licenca: CC BY-NC 4.0, Creative Commons Priznanje avtorstva-Nekomercialno 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by-nc/4.0/deed.sl
• Opis: Licenca Creative Commons, ki prepoveduje komercialno uporabo, vendar uporabniki ne rabijo upravljati materialnih avtorskih pravic na izpeljanih delih z enako licenco.

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: biokemija, G-kvadrupleksi, NMR, biofizika