Research Group "Chromatin Biology" (Jürg Müller)
The genomic DNA in nuclei of animal and plant cells is organized in form of chromosomes. The basic building block of chromosomes is the nucleosome. Nucleosomes consist of a protein complex made of histones around which 147 base pairs of DNA are wrapped in two helical turns. Neighboring nucleosomes are separated by only short stretches of free DNA and almost the complete genomic DNA is arranged in such arrays of nucleosomes, forming a structure known as chromatin. The removal, incorporation as well as the modification of histone proteins are key steps for almost all processes that occur on the DNA template. The Research Group “Chromatin Biology” led by Jürg Müller investigates how nucleosomes and post-translational modifications of histone proteins regulate gene transcription. Their research focuses on modifications that are generated by Polycomb- and Trithorax-protein complexes. The Polycomb/Trithorax system play a key role during animal and plant development: it ensures that regulator genes that control developmental programs are only expressed at the right time and in the right cells. The group studies the molecular mechanisms by which Polycomb- and Trithorax-protein complexes are specifically targeted to the genes that they regulate and how they modify their chromatin. A central aim of the group is to understand how inactive and active chromatin states are propagated through cell division and are thereby passed on to the next cell generation. The picture shows the phenotype of cells that lack the Polycomb protein Ph (cells with red signal only): the mutant cells have a severely altered morphology, are larger than normal cells (cells with green and red signal), and they form tumors in Drosophila.