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Interactions acides nucléiques/protéines non spécifiques : le nucléosome et les complexes de la NCp7

Abstract : Proteins regulate and perform the vital functions of organisms, in particular by interacting with nucleic acids (NA), including DNA which carries the genetic information. Understanding the nature of these interactions is central in biology. The nucleosome is the basic unit of DNA compaction in eukaryotes. Composed of a DNA wrapped around a histone core, this complex regulates the DNA accessibility by assembling and disassembling along the genome. Here, we carried out molecular dynamic simulations of the nucleosome in solution. The analysis of the DNA-histone interface with an innovative geometrical method highlighted the strong cohesion of the complex. Such an in-depth description of the interface was also used to interpret nucleosome assembly and disassembly experiments. Those experiments emphasized in particular the DNA sequence effect in both assembly and disassembly processes. Finally, the comparison between nucleosomal and free DNA dynamics showed which structural properties were conserved in the complex and how they contributed to the DNA-histone assembly efficiency. A similar strategy was used on experimental structures of NCp7, a HIV-1 NA chaperone protein, complexed with either DNA or RNA. The latter analysis suggested a rational basis to describe the mechanism of partner assembly. In both studies, I evidenced stepwise mechanisms of complex assemblies and I illustrated NA structure and sequence preferences of some so-called non-specific proteins.
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Submitted on : Friday, November 22, 2019 - 10:10:17 AM
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Romain Retureau. Interactions acides nucléiques/protéines non spécifiques : le nucléosome et les complexes de la NCp7. Sciences agricoles. Université Paris-Saclay, 2019. Français. ⟨NNT : 2019SACLN057⟩. ⟨tel-02375634⟩

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