Tautomers of a Fluorescent G Surrogate and Their Distinct Photophysics Provide Additional Information Channels.
Thienoguanosine ((th) G) is an isomorphic nucleoside analogue acting as a faithful fluorescent substitute of G, with respectable quantum yield in oligonucleotides. Photophysical analysis of (th) G reveals the existence of two ground-state tautomers with significantly shifted absorption and emission wavelengths, and high quantum yield in buffer. Using (TD)-DFT calculations, the tautomers were identified as the H1 and H3 keto-amino tautomers. When incorporated into the loop of (-)PBS, the (-)DNA copy of the HIV-1 primer binding site, both tautomers are observed and show differential sensitivity to protein binding. The red-shifted H1 tautomer is strongly favored in matched (-)/(+)PBS duplexes, while the relative emission of the H3 tautomer can be used to detect single nucleotide polymorphisms. These tautomers and their distinct environmental sensitivity provide unprecedented information channels for analyzing G residues in oligonucleotides and their complexes.
Laboratoire de Biophotonique et Pharmacologie Faculté de Pharmacie, UMR 7213 CNRS, Université de Strasbourg 74 route du Rhin, 67401 Illkirch (France).
Marianna
M
Sholokh
Consiglio Nazionale delle Ricerche Istituto di Biostrutture e Bioimmagini Via Mezzocannone 16, 80134 Napoli (Italy).
Roberto
R
Improta
Dipartimento di Biotecnologie, Chimica e Farmacia Università degli Studi di Siena Via Aldo Moro 2, 53100 Siena (Italy).
Mattia
M
Mori
Laboratoire de Biophotonique et Pharmacologie Faculté de Pharmacie, UMR 7213 CNRS, Université de Strasbourg 74 route du Rhin, 67401 Illkirch (France).
Rajhans
R
Sharma
Laboratoire de Biophotonique et Pharmacologie Faculté de Pharmacie, UMR 7213 CNRS, Université de Strasbourg 74 route du Rhin, 67401 Illkirch (France).
Cyril
C
Kenfack
Department of Chemistry and Biochemistry University of California, San Diego 9500 Gilman Dr, La Jolla, CA 92093-0358 (USA).
Dongwon
D
Shin
Department of Integrative Structural Biology, Institut de Génétique de Biologie Moléculaire et Cellulaire, INSERM U964 UMR 7104 CNRS, Université de Strasbourg, 67400 Illkirch (France).
Karine
K
Voltz
Department of Integrative Structural Biology, Institut de Génétique de Biologie Moléculaire et Cellulaire, INSERM U964 UMR 7104 CNRS, Université de Strasbourg, 67400 Illkirch (France).
Roland H
RH
Stote
Department of Chemistry Kyiv National Taras Shevchenko University 60 Volodymyrska street, 01033 Kyiv (Ukraine).
Olga A
OA
Zaporozhets
Dipartimento di Biotecnologie, Chimica e Farmacia Università degli Studi di Siena Via Aldo Moro 2, 53100 Siena (Italy).
Maurizio
M
Botta
Department of Chemistry and Biochemistry University of California, San Diego 9500 Gilman Dr, La Jolla, CA 92093-0358 (USA).
Yitzhak
Y
Tor
Laboratoire de Biophotonique et Pharmacologie Faculté de Pharmacie, UMR 7213 CNRS, Université de Strasbourg 74 route du Rhin, 67401 Illkirch (France).
Yves
Y
Mély
D001665:Binding Sites; D005456:Fluorescent Dyes / Q000737:chemistry*; D006151:Guanosine / Q000031:analogs & derivatives*; D015497:HIV-1 / Q000737:chemistry; D009841:Oligonucleotides / Q000737:chemistry*; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism
D005456:Fluorescent Dyes; D009841:Oligonucleotides; D006151:Guanosine
ab initio calculations; fluorescence; molecular modeling; nucleic acids; tautomerism