Project description
A good look at chromatin remodelling
The long strands of DNA making up chromosomes are wrapped around proteins, sort of like thread on a spool, to fit them in the nucleus. This condensed form of DNA is called chromatin. For transcription and cell division to take place, the chromatin is 'remodelled' to enable access to DNA. This is a critical step in development, cell differentiation, and pathological processes such as cancer. However, its mechanisms remain poorly understood due to the structural complexity of the molecules. INO3D is employing Nobel-winning transmission electron cryomicroscopy (cryo-TEM) to provide a window on biological structures at the atomic level during chromatin remodelling by the INO80 molecule. Results could provide the first glimpses of INO80 in action.
Objective
Nucleosomes, ~147 base pairs of DNA wrapped around an histone protein octamer, package and protect nuclear DNA but also carry important biological information. The position and composition of nucleosomes along chromosomal DNA is a key element of defining the state and identity of a cell. Chromatin remodellers are ATP dependent molecular machines that position, move or edit nucleosomes in a genome wide manner. Collectively, they shape the nucleosome landscape and play central roles in the maintenance and differentiation of cells, but also in pathological transformations. INO80, a megadalton large remodeller consisting of 15 or more subunits, is involved in replication, gene expression and DNA repair. It models chromatin by positioning barrier nucleosomes around nucleosome free regions, editing nucleosomes and generating nucleosome arrays. However, structural mechanisms for INO80 and other remodelling machines are poorly understood due to their complexity. To provide a comprehensive mechanistic framework, to understand how INO80 senses nucleosome free regions to position barrier nucleosomes and how it generates arrays or senses DNA breaks, I propose a challenging but ground-breaking endeavour using a combination of cryo-EM and functional approaches. We address structures of fungal and human INO80 complexes at promoter regions, on di-nucleosomes and at DNA ends and develop quantitative positioning assays to reveal common and distinct features of shaping chromatin in different species. We also explore cryo-EM as tool towards revealing distinct steps the chemo-mechanical remodelling reactions. The proposed research will help derive fundamental molecular principles underlying the modelling of the nucleosome landscape.
Fields of science
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Funding Scheme
ERC-ADG - Advanced GrantHost institution
80539 MUNCHEN
Germany