Nikolay Zolotarev1,2, Yuanting Wang1, Manyu Du2, Marc Bayer1, Anna Grosschedl2, Ibrahim Cisse2 and Rudolf Grosschedl1 1Laboratory of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany; 2Department of Biological Physics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg 79108, Germany Corresponding author: grosschedlie-freiburg.mpg.de Abstract

B lineage priming by pioneer transcription factor EBF1 requires the function of an intrinsically disordered region (IDR). Here, we examine the role of regularly spaced tyrosines in the IDR as potential determinants of IDR function and activity of EBF1. We found that four Y > A mutations in EBF1 reduced the formation of condensates in vitro and subdiffractive clusters in vivo. Notably, Y > A mutant EBF1 was inefficient in promoting B cell differentiation and showed impaired chromatin binding, recruitment of BRG1, and activation of specific target genes. Thus, regularly spaced tyrosines in the IDR contribute to the biophysical and functional properties of EBF1.

Received May 26, 2023. Accepted December 21, 2023.