BPCPPDYSOE21 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 14: Focus Phase Separation in Biological Systems I (joint session BP/CPP)
BP 14.1: Vortrag
Dienstag, 23. März 2021, 09:00–09:20, BPc
Intranuclear Phase Separation of a Chromatin Scaffolding Protein — •Davide Michieletto1, Mattia Marenda1, David Zwicker2, and Jan Kirschbaum2 — 1University of Edinburgh — 2Max Planck Institute for Dynamics and Self-Organization
The formation and regulation of phase separated condensates is now widely seen in vitro and cytoplasm, but far more challenging to observe and test in the cell nucleus. In this talk I will present recent work on an abundant nuclear RNA-binding protein called Scaffold Attachment Factor A, or SAF-A, that regulates chromatin decompaction at transcriptionally active loci through its interaction with RNA. Here I show that the intrinsically disordered RNA binding domain of SAFA * known as an RGG domain -- undergoes phase separation upon transcriptional inhibition and that the size of the condensates can be controlled by tuning the amount arginine/lysine residues in the RGG domain. By expressing a longer, and closer to native, SAFA domain we observe that the phase separation is suppressed. To explain our findings, we propose an equilibrium model in which a slowly diffusing RNA substrate can sequester RGG fragments; upon transcriptional inhibition the freed up fragments can undergo phase separation via weak self-interactions.