Nanomechanics of G-quadruplexes within the promoter of the KIT oncogene |
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Authors: | Enrico Buglione Domenico Salerno Claudia Adriana Marrano Valeria Cassina Guglielmo Vesco Luca Nardo Mauro Dacasto Riccardo Rigo Claudia Sissi Francesco Mantegazza |
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Affiliation: | School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy;Department of Comparative Biomedicine and Food Science, University of Padova, 35020 Legnaro (PD), Italy;Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova (PD), Italy;Interdepartmental Research Center for Innovative Biotechnologies (CRIBI), University of Padova, 35121 Padova (PD), Italy |
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Abstract: | G-quadruplexes (G4s) are tetrahelical DNA structures stabilized by four guanines paired via Hoogsteen hydrogen bonds into quartets. While their presence within eukaryotic DNA is known to play a key role in regulatory processes, their functional mechanisms are still under investigation. In the present work, we analysed the nanomechanical properties of three G4s present within the promoter of the KIT proto-oncogene from a single-molecule point of view through the use of magnetic tweezers (MTs). The study of DNA extension fluctuations under negative supercoiling allowed us to identify a characteristic fingerprint of G4 folding. We further analysed the energetic contribution of G4 to the double-strand denaturation process in the presence of negative supercoiling, and we observed a reduction in the energy required for strands separation. |
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