Linker histone H1 plays an important role in chromatin folding and genic regulation. In mammals has been identified 6 somatic subtypes, H1a-e, 2 germline-specific subtypes, H1t i H1oo and 2 subtypes related to diferenciation, H10 i H1x. H1 linker histones present a tripartite structure consisting of a central globular domain flanked by N- and C-terminal tail-like domains. We characterize the effect of phosphorylation of C-terminal domain of H10 upon the interaction with DNA. The phosphorilated domain maintains the preferential binding to SAR sequences and the cooperative binding to DNA. We analyze by circular dicroism the domain and its phosphorilated species with different DNA fragments. The phosphorilated species induces an intense ψ spectrum than the non-phosphorilated domain, showing a higher organized aggregation capacity of the DNA. Competition experiments determined that relative affinity for DNA when the domain is phosphorilated decrease approximately 3-fold. We studied the effects of phosphorylation on the secondary structure of H1e and its carboxy-terminal domain by Fourier transform infrared spectroscopy (FTIR). Phosphorilation of H1e leads to a structural change in the protein: a decrease of α-helix and an increase of β-sheet. The secondary structuration grade depends both of position and number of phosphate groups. Histone H1e phosphorylation has different effects in its phosphorilated species upon relativity affinities for DNA and aggregation capacity of DNA. The species with more grade of phosphorilation shows less affinity for DNA but more aggregation capacity of DNA. Furthermore, these same species are which contains a more β-sheet structure, favoring the formation of DNA-protein aggregates.
Efectes de la fosforilació sobre l'estructura i la interacció amb el DNA de la histona H1 i el seu domini C-terminal
Teruel Romia, N. (Author). 20 Oct 2011
Student thesis: Doctoral thesis
Student thesis: Doctoral thesis