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UID:20260201T174948EST-9347AhGKKU@132.216.98.100
DTSTAMP:20260201T224948Z
DESCRIPTION: “DNA comes in many forms” (A. Rich): a number of non-classical
  pairing patterns are possible between or within DNA strands. These intera
 ctions result in the formation of unusual structures\, among them the G-qu
 adruplex and the i-motif. G-quadruplexes (G4) result from the stacking of 
 several G-quartets (formed by hydrogen bonding of four coplanar guanines)\
 , and are stabilized by monocations such as sodium and potassium. These st
 ructures are very stable under physiological conditions but were first tho
 ught to be an in vitro anomaly. Critical evidence for the biological relev
 ance of G4 has come from use of G4-specific antibodies and results obtaine
 d in a variety of organisms. We are now using novel strategies\, including
  new analytical tools and a unique model organism\, to confirm the importa
 nce of G-quadruplexes and study their properties. We first developed a new
  algorithm for prediction of G4 propensity (1). We developed new assays to
  identify and analyze selective G4 ligands (2\,3). We provide evidence for
  G4 existence in living cells using in vivo NMR (4). Having established th
 at quadruplex-prone regions are conserved in the genome of viruses\, we ar
 e currently investigating whether quadruplexes may become the Achilles' He
 el of the viral life cycle (5\,6).\n\nIn addition\, besides their importan
 ce in Biology\, unusual nucleic acid structures may find applications in B
 iotechnologies and Nanotechnologies. These structures create a greater div
 ersity of DNA-based building blocks for nanomaterials and have clear advan
 tages over conventional duplex DNA\, such as enhanced thermal stability\, 
 conductivity\, and sensitivity to chemical stimuli (for a review: (7)). A 
 major drawback of G4 and i-DNA designs is the lack of control over the ass
 embly process due to a homo-recognition problem: as G-quartets are formed 
 from four identical bases\, a guanine from one G-rich strand can bond with
  its own strand or with another strand at any of the guanines. We recently
  provided solutions to this problem\, using either parallel-stranded (8) o
 r canonical antiparallel (9\, 10) DNA duplexes to direct the controlled as
 sembly of G4 structures and i-motifs. Finally\, we recently demonstrated t
 hat G-rich DNA sequences may function as a double switch whose function is
  based on different triggers provided that their secondary structures and 
 stability display a high dependence on cation nature and concentration (11
 ).\n\n(1) Bedrat et al.\, Nucleic Acids Res. 2016\, 44: 1746\n\n(2) Mendoz
 a et al.\, Nucleic Acids Res. 2015\, 43: e71\n\n(3) De Rache et al.\, Bioc
 himie 2015\, 115: 194\n\n(4) Salgado et al.\, Chem. Sci. 2015\, 6: 3273\n
 \n(5) Amrane et al.\, J. Am. Chem. Soc 2014\, 136: 5249\n\n(6) Métifiot et
  al.\, Biochimie 2015\, 118: 173\n\n(7) Yatsunyk\, Mendoza & Mergny.\, Acc
 . Chem. Res. 2014\, 47: 1836\n\n(8) Yatsunyk et al\, ACS Nano 2013\, 7: 57
 01\n\n(9) Mendoza et al.\, Chem. Eur. J. 2015\, 21: 6732\n\n(10) Fu et al.
 \, 2016\, in preparation\n\n(11) Largy et al.\, J. Am. Chem. Soc. 2016\, 1
 38: 2780\n
DTSTART:20160915T170000Z
DTEND:20160915T183000Z
LOCATION:Rm 1B39\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue S
 herbrooke Ouest
SUMMARY:Chemical Society Seminar: Dr. Jean-Louis Mergny - Quadruplexes are 
 Everywhere!
URL:/chemistry/channels/event/chemical-society-seminar
 -dr-jean-louis-mergny-quadruplexes-are-everywhere-262026
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