Influence of site-specific posttranslational modifications on H1-mediated chromatosome condensation

• Applicant: Professor Dr. Florian Stengel
• Subject Area: General Genetics and Functional Genome Biology ; Biochemistry ; Biological and Biomimetic Chemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 564405661

Molecular condensates offer a confined space where specific protein protein interactions can take place, for example to facilitate distinct biochemical reactions, and posttranslational modifications (PTMs) play an important role in their organization. Despite extensive efforts, our current knowledge of how proteins are organized within condensates is limited and monitoring the transient interactions inside condensates has been a major challenge to the field. As the formation of condensates appears to be of fundamental relevance to biology, it is critical to understand the underlying molecular interactions and how they are affected by PTMs. By combining bio-orthogonal chemistry, biochemistry, and MS-based proteomics we will study the influence of site-specific PTMs on H1-mediated chromatosome condensation. Specifically, we will investigate the molecular basis of site-specific ubiquitylation and acetylation on H1-mediated chromatosome condensation and how it is modulated by SIRT1 and p53 in vitro. Using confocal miscroscopy, enzymatic assays, cross-linking mass spectrometry and cryo-EM we will investigate how acetylation and ubiquitylation of linker histone H1 influence condensate formation and organization of intact chromatosomes in vitro and how it is modulated by SIRT1 and p53. In a second part we will study linker histone induced chromatin condensates in cell lysates. To do so we will generate H1-variant specific chromatin condensates in cell lysates and analyze them by MS-based proteomics and next-generation sequencing (NGS). In combination, the research described in this proposal will advance our molecular understanding of how site-specific acetylation and ubiquitylation of linker histone H1 influence chromatosome condensation.

• DFG Programme: Research Grants