Sonja M Wiedemann

Publications (2)18.29 Total impact

• Source

  Available from: Lothar Schermelleh

  Article: H2A.Z.2.2 is an alternatively spliced histone H2A.Z variant that causes severe nucleosome destabilization.

  Clemens Bönisch, Katrin Schneider, Sebastian Pünzeler, Sonja M Wiedemann, Christina Bielmeier, Marco Bocola, H Christian Eberl, Wolfgang Kuegel, Jürgen Neumann, Elisabeth Kremmer, Heinrich Leonhardt, Matthias Mann, Jens Michaelis, Lothar Schermelleh, Sandra B Hake
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  ABSTRACT: The histone variant H2A.Z has been implicated in many biological processes, such as gene regulation and genome stability. Here, we present the identification of H2A.Z.2.2 (Z.2.2), a novel alternatively spliced variant of histone H2A.Z and provide a comprehensive characterization of its expression and chromatin incorporation properties. Z.2.2 mRNA is found in all human cell lines and tissues with highest levels in brain. We show the proper splicing and in vivo existence of this variant protein in humans. Furthermore, we demonstrate the binding of Z.2.2 to H2A.Z-specific TIP60 and SRCAP chaperone complexes and its active replication-independent deposition into chromatin. Strikingly, various independent in vivo and in vitro analyses, such as biochemical fractionation, comparative FRAP studies of GFP-tagged H2A variants, size exclusion chromatography and single molecule FRET, in combination with in silico molecular dynamics simulations, consistently demonstrate that Z.2.2 causes major structural changes and significantly destabilizes nucleosomes. Analyses of deletion mutants and chimeric proteins pinpoint this property to its unique C-terminus. Our findings enrich the list of known human variants by an unusual protein belonging to the H2A.Z family that leads to the least stable nucleosome known to date.
  Nucleic Acids Research 03/2012; 40(13):5951-64. · 8.03 Impact Factor
• Source

  Available from: Tobias Straub

  Article: Identification and characterization of two novel primate-specific histone H3 variants, H3.X and H3.Y.

  Sonja M Wiedemann, Silke N Mildner, Clemens Bönisch, Lars Israel, Andreas Maiser, Sarah Matheisl, Tobias Straub, Rainer Merkl, Heinrich Leonhardt, Elisabeth Kremmer, Lothar Schermelleh, Sandra B Hake
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  ABSTRACT: Nucleosomal incorporation of specialized histone variants is an important mechanism to generate different functional chromatin states. Here, we describe the identification and characterization of two novel primate-specific histone H3 variants, H3.X and H3.Y. Their messenger RNAs are found in certain human cell lines, in addition to several normal and malignant human tissues. In keeping with their primate specificity, H3.X and H3.Y are detected in different brain regions. Transgenic H3.X and H3.Y proteins are stably incorporated into chromatin in a similar fashion to the known H3 variants. Importantly, we demonstrate biochemically and by mass spectrometry that endogenous H3.Y protein exists in vivo, and that stress stimuli, such as starvation and cellular density, increase the abundance of H3.Y-expressing cells. Global transcriptome analysis revealed that knockdown of H3.Y affects cell growth and leads to changes in the expression of many genes involved in cell cycle control. Thus, H3.Y is a novel histone variant involved in the regulation of cellular responses to outside stimuli.
  The Journal of Cell Biology 09/2010; 190(5):777-91. · 10.26 Impact Factor