UMR9187 / U1196 – Chemistry, Modelling and Imaging for Biology (CMIB)

Unit publications

Year of publication 2018

Michela Zuffo, Xiao Xie, Anton Granzhan (2018 Dec 6)

Strength in Numbers: Development of a Fluorescence Sensor Array for Secondary Structures of DNA.

Chemistry - A European Journal : DOI : 10.1002/chem.201805422 Learn more
Summary

GA-ChemEurJ-2018-3High-throughput assessment of secondary structures adopted by DNA oligonucleotides is currently hampered by the lack of suitable biophysical methods. Fluorescent sensors hold great potential in this respect; however, the moderate selectivity that they display for one DNA conformation over the others constitutes a major drawback to the development of accurate assays. Moreover, the use of single sensors impedes a comprehensive classification of the tested sequences. Herein, we propose to overcome these limitations through the development of a fluorescence sensor array constituted by easily accessible, commercial dyes. Multivariate analysis of the emission data matrix produced by the array allows to explore the conformational preferences of DNA sequences of interest, either by calculating the probability of group membership in the six predefined structural categories (three G-quadruplex groups, double-stranded, and two groups of single-stranded forms), or by revealing their particular structural features. The assay enables rapid screening of synthetic DNA oligonucleotides in a 96-wells plate format.

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Coralie Caron, Xuan N T Duong, Régis Guillot, Sophie Bombard, Anton Granzhan (2018 Dec 4)

Interaction of Functionalized Naphthalenophanes with Abasic Sites in DNA: DNA Cleavage, DNA Cleavage Inhibition, and Formation of Ligand-DNA Adducts.

Chemistry - A European Journal : DOI : 10.1002/chem.201805555 Learn more
Summary

GA-ChemEurJ-2018-2Ligands interacting with abasic (AP) sites in DNA may generate roadblocks in base-excision DNA repair (BER) due to indirect inhibition of DNA repair enzymes (e.g., APE1) and/or formation of toxic byproducts, resulting from ligand-induced strand cleavage or covalent cross-links. Herein, we prepared and systematically studied a series of 12 putative AP-site ligands, sharing the common naphthalenophane scaffold but endowed with a variety of substituents. Our results demonstrate that most naphthalenophanes bind to AP-sites in DNA and inhibit the APE1-induced hydrolysis of the latter in vitro. Remarkably, their APE1 inhibitory activity, as characterized by IC50 and Ki values, can be directly related to their affinity and selectivity to AP-sites, assessed from the fluorescence-melting experiments. On the other hand, the molecular design of naphthalenophanes has crucial influence on their intrinsic AP-site cleavage activity (i.e., ligand-catalyzed β- and β,δ-elimination reactions at the AP site), as illustrated by the compounds either having an exceptionally high AP-site cleavage activity (e.g., 2,7 BisNP-S, 125-fold more efficacious than spermine) or totally devoid of this activity (four compounds). Finally, we reveal the unprecedented formation of a stable covalent DNA adduct upon reaction of one ligand (2,7-BisNP-NH) with its own product of AP-site cleavage.

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Partouche D., Turbant F., El Hamoui O., Campidelli C., Bombled M., Trépout S., Wien F., Arluison V. (2018 Dec 1)

Epigallocatechin Gallate Remodelling of Hfq Amyloid-Like Region Affects Escherichia coli Survival

Pathogens : 7 : 95 : DOI : 10.3390/pathogens7040095 Learn more
Summary

Hfq is a pleiotropic regulator that has key roles in the control of genetic expression. The protein noticeably regulates translation efficiency and RNA decay in Gram-negative bacteria, due to the Hfq-mediated interaction between small regulatory noncoding RNA and mRNA. This property is of primary importance for bacterial adaptation and virulence. We have previously shown that the Hfq E. coli protein, and more precisely its C-terminal region (CTR), self-assembles into an amyloid-like structure. In the present work, we demonstrate that epigallocatechin gallate (EGCG), a major green tea polyphenol compound, targets the Hfq amyloid region and can be used as a potential antibacterial agent. We analysed the effect of this compound on Hfq amyloid fibril stability and show that EGCG both disrupts Hfq-CTR fibrils and inhibits their formation. We show that, even if EGCG affects other bacterial amyloids, it also specifically targets Hfq-CTR in vivo. Our results provide an alternative approach for the utilisation of EGCG that may be used synergistically with conventional antibiotics to block bacterial adaptation and treat infections.

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Prado Martins R., Findakly S., Daskalogianni C., Teulade-Fichou M.P., Blondel M., Fåhraeus R. (2018 Nov 29)

In Cellulo Protein-mRNA Interaction Assay to Determine the Action of G-Quadruplex-Binding Molecules

Molecules : 23 : 3124 : DOI : 10.3390/molecules23123124 Learn more
Summary

Protein-RNA interactions (PRIs) control pivotal steps in RNA biogenesis, regulate multiple physiological and pathological cellular networks, and are emerging as important drug targets. However, targeting of specific protein-RNA interactions for therapeutic developments is still poorly advanced. Studies and manipulation of these interactions are technically challenging and in vitro drug screening assays are often hampered due to the complexity of RNA structures. The binding of nucleolin (NCL) to a G-quadruplex (G4) structure in the messenger RNA (mRNA) of the Epstein-Barr virus (EBV)-encoded EBNA1 has emerged as an interesting therapeutic target to interfere with immune evasion of EBV-associated cancers. Using the NCL-EBNA1 mRNA interaction as a model, we describe a quantitative proximity ligation assay (PLA)-based in cellulo approach to determine the structure activity relationship of small chemical G4 ligands. Our results show how different G4 ligands have different effects on NCL binding to G4 of the EBNA1 mRNA and highlight the importance of in-cellulo screening assays for targeting RNA structure-dependent interactions.

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