TY - JOUR TI - Peptides that Mimic RS repeats modulate phase separation of SRSF1, revealing a reliance on combined stacking and electrostatic interactions AU - Fargason, Talia AU - De Silva, Naiduwadura Ivon Upekala AU - King, Erin AU - Zhang, Zihan AU - Paul, Trenton AU - Shariq, Jamal AU - Zaharias, Steve AU - Zhang, Jun A2 - Black, Douglas L A2 - Manley, James L A2 - Kojetin, Douglas J VL - 12 PY - 2023 DA - 2023/03/02 SP - e84412 C1 - eLife 2023;12:e84412 DO - 10.7554/eLife.84412 UR - https://doi.org/10.7554/eLife.84412 AB - Phase separation plays crucial roles in both sustaining cellular function and perpetuating disease states. Despite extensive studies, our understanding of this process is hindered by low solubility of phase-separating proteins. One example of this is found in SR and SR-related proteins. These proteins are characterized by domains rich in arginine and serine (RS domains), which are essential to alternative splicing and in vivo phase separation. However, they are also responsible for a low solubility that has made these proteins difficult to study for decades. Here, we solubilize the founding member of the SR family, SRSF1, by introducing a peptide mimicking RS repeats as a co-solute. We find that this RS-mimic peptide forms interactions similar to those of the protein’s RS domain. Both interact with a combination of surface-exposed aromatic residues and acidic residues on SRSF1’s RNA Recognition Motifs (RRMs) through electrostatic and cation-pi interactions. Analysis of RRM domains from human SR proteins indicates that these sites are conserved across the protein family. In addition to opening an avenue to previously unavailable proteins, our work provides insight into how SR proteins phase separate and participate in nuclear speckles. KW - SRSF1 KW - phase separation KW - cation-pi interaction KW - intrinsically disordered protein KW - NMR KW - SR proteins JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -