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Johnson S, Paul T, Sanford S, Schnable BL, Detwiler A, Thosar S, Van Houten B, Myong S, Opresko P. BG4 antibody can recognize telomeric G-quadruplexes harboring destabilizing base modifications and lesions. Nucleic Acids Res 2024; 52:1763-1778. [PMID: 38153143 PMCID: PMC10939409 DOI: 10.1093/nar/gkad1209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 11/30/2023] [Accepted: 12/11/2023] [Indexed: 12/29/2023] Open
Abstract
BG4 is a single-chain variable fragment antibody shown to bind various G-quadruplex (GQ) topologies with high affinity and specificity, and to detect GQ in cells, including GQ structures formed within telomeric TTAGGG repeats. Here, we used ELISA and single-molecule pull-down (SiMPull) detection to test how various lengths and GQ destabilizing base modifications in telomeric DNA constructs alter BG4 binding. We observed high-affinity BG4 binding to telomeric GQ independent of telomere length, although three telomeric repeat constructs that cannot form stable intramolecular GQ showed reduced affinity. A single guanine substitution with 8-aza-7-deaza-G, T, A, or C reduced affinity to varying degrees depending on the location and base type, whereas two G substitutions in the telomeric construct dramatically reduced or abolished binding. Substitution with damaged bases 8-oxoguanine and O6-methylguanine failed to prevent BG4 binding although affinity was reduced depending on lesion location. SiMPull combined with FRET revealed that BG4 binding promotes folding of telomeric GQ harboring a G to T substitution or 8-oxoguanine. Atomic force microscopy revealed that BG4 binds telomeric GQ with a 1:1 stoichiometry. Collectively, our data suggest that BG4 can recognize partially folded telomeric GQ structures and promote telomeric GQ stability.
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Affiliation(s)
- Samuel A Johnson
- Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA
- Molecular Biophysics and Structural Biology Graduate Program, University of Pittsburgh, PA 15260, USA
| | - Tapas Paul
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Samantha L Sanford
- Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Brittani L Schnable
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA
- Molecular Biophysics and Structural Biology Graduate Program, University of Pittsburgh, PA 15260, USA
| | - Ariana C Detwiler
- Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Sanjana A Thosar
- Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Bennett Van Houten
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA
- Molecular Biophysics and Structural Biology Graduate Program, University of Pittsburgh, PA 15260, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, PA 15213, USA
| | - Sua Myong
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA
- Molecular Biophysics and Structural Biology Graduate Program, University of Pittsburgh, PA 15260, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, PA 15213, USA
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