H2A.Z-nucleosomes are stabilized by the superhelicity-dependent DNA binding of the C-terminal tail of the histone variant

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dc.contributor.advisorSzabó, Gábor
dc.contributor.advisorVámosi, György
dc.contributor.authorBenhamza, Ibtissem
dc.contributor.authorvariantIbtissem
dc.contributor.departmentMolekuláris sejt- és immunbiológia doktori iskolahu
dc.contributor.submitterdepÁltalános Orvostudományi Kar::Biofizikai és Sejtbiológiai Intézet
dc.date.accessioned2026-03-12T10:31:45Z
dc.date.available2026-03-12T10:31:45Z
dc.date.defended2026-03-27
dc.date.issued2025
dc.description.abstractUsing an in situ assay of nucleosome stability called QINESIn, developed in our lab, recording elution curves indicative of the off-rate of specific histones released from nucleosomes upon exposure to salt or intercalator, I studied the stability of the nucleosomes containing the histone variant H2A.Z. The distinct stability features of H2A.Z nucleosome were found to be dependent on the C-terminal H2A.Z tail in the salt-elution format of QINESIn, which assesses intrinsic nucleosome stability. Moreover, the stability features of H2A.Z-nucleosomes could be modulated when we introduced a synthetic peptide resembling the C-terminal H2A.Z tail into live cells using a cyclodextrin-based procedure. These findings were further validated with an alternative approach, the intercalator-elution format of QINESIn, using the intercalating agents EBr and Dox, a assessing nucleosome stability by altering DNA superhelicity, rather than disrupting ionic and hydrogen bonds with salt. Importantly, the changes in DNA superhelicity naturally occur in vivo during e.g. transcriptional processes, suggesting that the differences in nucleosome stability detected by this assay may have direct biological significance. Using a DT40 cell line pair expressing either the full-length human H2A.Z1 or its C-terminally truncated version, we found that nucleosome stability is tail-dependent also through the spectacles of intercalator sensitivity. This conclusion was confirmed in experiments studying the binding of Dox-Biotin to DNA. Fluorescence correlation spectroscopy (FCS) also supported these findings, when I revealed that the H2A.Z-tail nonapeptide preferentially binds to supercoiled rather than relaxed-plasmid DNA. The DNA topology-dependent binding of the unstructured C-terminal tail of H2A.Z, by modulating nucleosome stability, may be functionally significant in various roles of the histone variant as shown in our cell proliferation studies. Our work demonstrates the interplay between DNA topology and nucleosome stability and opens new avenues for further studies on how it may be exploited by the cell for regulatory functions.
dc.format.extent89
dc.identifier.urihttps://hdl.handle.net/2437/405500
dc.language.isoen
dc.subjectC-terminal H2A.Z tail, Superhelicity, Nucleosome stability
dc.subject.disciplineElméleti orvostudományokhu
dc.subject.sciencefieldOrvostudományokhu
dc.titleH2A.Z-nucleosomes are stabilized by the superhelicity-dependent DNA binding of the C-terminal tail of the histone variant
dc.title.translatedA H2A.Z-nukleoszómákat a hisztonvariáns C-terminális farka a DNA szuperhelicitásától függő módon stabilizálja.
dc.typePhD, doktori értekezéshu
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Molekuláris Sejt- és Immunbiológia Doktori Iskola