Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2021
Erindi/veggspjald / Talk/poster E49
Höfundar / Authors: Sigríður St. Hlynsdóttir (1,2), Pétur Orri Heiðarsson (1,2)
Starfsvettvangur / Affiliations: 1. The Science Institute, Department of Biochemistry, University of Iceland, 2. Biomedical Center, University of Iceland
Kynnir / Presenter: Sigríður St. Hlynsdóttir
PU.1 is a pioneer transcription factor (pTF) in the hematopoietic lineage which has been implicated in various blood disorders and diseases. As a pTF, PU.1 targets and binds to condensed chromatin and initiates cell fate changes. Besides its C-terminal DNA binding domain, PU.1´s ~170 residue long N-terminal includes the transactivation domain and is an intrinsically disordered region (IDR). The IDR is important for PU.1´s pioneer activity through a poorly understood mechanism but these regions may be important to recruit other TFs or interact with core histones or nucleosomal DNA. Although PU.1 has been identified as a potential therapeutic target, little is known about the biochemical and biophysical properties of the protein. Single-molecule spectroscopy in combination with FRET is a powerful method to study the dynamics of IDRs. Site-specific labeling enables probing of distances within a disordered region as well as interactions between two molecules. Our results show that PU.1 binds to short DNA harboring its recognition sequence with high affinity and that the binding alters the conformations of the disordered N-terminal tail. We also detected dimer formation on DNA with low nanomolar affinity that affects the conformations of the IDR. Whether the dimer forms on nucleosomes and what role it might have is currently unknown. By characterizing the physical principles behind PU.1’s function, we may unlock a useful tool in research of the hematopoietic system.