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Séminaire LCP Valérie Gabelica - vendredi 24 mai 2019 à 14h

Séminaire LCP Valérie Gabelica - vendredi 24 mai 2019 à 14h

Valérie Gabelica, Institut Européen de Chimie et Biologie, Bordeaux

Vendredi 24 mai à 14h (salle Magat) :

“Studying G-Quadruplex Nucleic Acids Folding by Combining Circular Dichroism and Mass Spectrometry”

Our group is interested in elucidating the folding of guanine-rich DNA or RNA sequences into G-quadruplex structures, and how cations or ligands influence the folding in solution. Solution spectroscopy, and in particular, circular dichroism (CD) spectrophotometry, are very useful to study G-quadruplex folding because the signal indicates the type of stacking between the guanine quartets. In parallel, we developed mass spectrometry (MS) approaches to probe the stoichiometries formed between the DNA strands, the cations and the ligands. By combining the information obtained from both methods on the same sample, we can infer the folding mechanisms, and how cation or ligand binding induces shifts in the G-quadruplex topologies.[1-5] We will also show recent results with the first true hyphenation of CD and MS, by recording the circular dichroism effect on trapped G-quadruplex ions. For that, we exploited electron photodetachment from multiply charged DNA anions.[6-8] Time permitting, we will also discuss the TD-DFT calculation of CD spectra of G-quadruplexes, which can aid the interpretation of unusual CD signatures.

(1) Marchand, A. ; Granzhan, A. ; Iida, K. ; Tsushima, Y. ; Ma, Y. ; Nagasawa, K. ; Teulade-Fichou, M. P. ; Gabelica, V. "Ligand-Induced Conformational Changes with Cation Ejection upon Binding to Human Telomeric DNA G-Quadruplexes" J. Am. Chem. Soc. 2015, 137, 750-756.
(2) Marchand, A. ; Strzelecka, D. ; Gabelica, V. "Selective and Cooperative Ligand Binding to Antiparallel Human Telomeric DNA G-Quadruplexes" Chem. Eur. J. 2016, 22, 9551-9555.
(3) Marchand, A. ; Gabelica, V. "Folding and misfolding pathways of G-quadruplex DNA" Nucleic Acids Res. 2016, 44, 10999-11012.
(4) Lecours, M. J. ; Marchand, A. ; Anwar, A. ; Guetta, C. ; Hopkins, W. S. ; Gabelica, V. "What stoichiometries determined by mass spectrometry reveal about the ligand binding mode to G-quadruplex nucleic acids" Biochim. Biophys. Acta 2017, 1861, 1353–1361.
(5) Marchand, A. ; Rosu, F. ; Zenobi, R. ; Gabelica, V. "Thermal Denaturation of DNA G-Quadruplexes and Their Complexes with Ligands : Thermodynamic Analysis of the Multiple States Revealed by Mass Spectrometry" J. Am. Chem. Soc. 2018, 140, 12553-12565.
(6) Gabelica, V. ; Tabarin, T. ; Antoine, R. ; Rosu, F. ; Compagnon, I. ; Broyer, M. ; De Pauw, E. ; Dugourd, P. "Electron photodetachment dissociation of DNA polyanions in a quadrupole ion trap mass spectrometer" Anal. Chem. 2006, 78, 6564-6572.
(7) Gabelica, V. ; Rosu, F. ; Tabarin, T. ; Kinet, C. ; Antoine, R. ; Broyer, M. ; De Pauw, E. ; Dugourd, P. "Base-dependent electron photodetachment from negatively charged DNA strands upon 260-nm laser irradiation" J. Am. Chem. Soc. 2007, 129, 4706-4713.
(8) Daly, S. ; Porrini, M. ; Rosu, F. ; Gabelica, V. "Electronic Spectroscopy of Isolate Nucleic Acid Polyanions" Faraday Discuss. 2019, 10.1039/C1038FD00207J.



  • Vendredi 24 mai 14:00-15:30 -

    Séminaire LCP Valérie Gabelica - vendredi 24 mai 2019 à 14h

    Lieu : Orsay - Laboratoire de Chimie Physique, salle Magat
    Université Paris Sud et CNRS - UMR8000
    Bâtiment 349

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