Abstract
Liquid-liquid phase separation (LLPS) constitutes a crucial phenomenon in biological self-organization, not only intervening in the formation of membraneless organelles but also triggering pathological protein aggregation, which is a hallmark in neurodegenerative diseases. Employing incoherent quasi-elastic neutron spectroscopy (QENS), we examine the short-time self-diffusion of a model protein undergoing LLPS as a function of phase splitting and temperature to access information on the nanosecond hydrodynamic response to the cluster formation both within and outside the LLPS regime. We investigate the samples as they dissociate into microdroplets of a dense protein phase dispersed in a dilute phase as well as the separated dense and dilute phases obtained from centrifugation. By interpreting the QENS results in terms of the local concentrations in the two phases determined by UV-vis spectroscopy, we hypothesize that the short-time transient protein cluster size distribution is conserved at the transition point while the local volume fractions separate.
| Original language | English |
|---|---|
| Pages (from-to) | 12051-12059 |
| Number of pages | 9 |
| Journal | Journal of Physical Chemistry Letters |
| Volume | 15 |
| Issue number | 48 |
| DOIs | |
| State | Published - Dec 5 2024 |
Funding
This research used resources at the Spallation Neutron Source (SNS), a Department of Energy (DOE) Office of Science User Facility operated by the Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA. This work is based on experiments performed at the BASIS spectrometer supported by Ju\u0308lich Center for Neutron Science (JCNS) at the SNS/ORNL, which the authors thank for beamtime allocation. I.M. and T.S. gratefully acknowledge the financial support provided by JCNS to perform the neutron scattering measurements at the SNS and thank R. Moody for the excellent support in the SNS chemistry laboratory. Since the fragile samples had to be prepared on site, the experiment benefited from the laboratory infrastructure on site. Moreover, the authors acknowledge funding by DFG-ANR German-French collaborative grants (ANR-16-CE92-0009, ANR-21-CE06-0047/DFG SCHR700/28-1, DFG SCHR700/42-1) and by the BMBF (ErUM-pro 05K19VTB and 05K22VTA). I.M. acknowledges an ILL PhD studentship in the spectroscopy group funded by InnovaXN, a EU Horizon 2020 MSCA COFUND programme (www.innovaxn.eu, Grant 847439). This work also used tools and laboratories of the PSCM (https://pscm-grenoble.eu/) with support from ESRF and ILL in Grenoble.