RT Journal Article
SR Electronic
T1 Interplay of folded domains and the disordered low-complexity domain in mediating hnRNPA1 phase separation
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.05.15.096966
DO 10.1101/2020.05.15.096966
A1 Nicole M. Milkovic
A1 F. Emil Thomasen
A1 Matthew J. Cuneo
A1 Christy R. Grace
A1 Erik W. Martin
A1 Amanda Nourse
A1 Kresten Lindorff-Larsen
A1 Tanja Mittag
YR 2020
UL http://biorxiv.org/content/early/2020/05/16/2020.05.15.096966.abstract
AB Liquid-liquid phase separation has emerged as a new paradigm for the compartmentalization of cells without membranes. Intrinsically disordered low-complexity domains (LCDs) are often sufficient for mediating phase separation, but how their phase behavior is modulated by the presence of attached folded domains is incompletely understood. Here, we interrogate the interplay between folded and disordered domains of the RNA-binding protein hnRNPA1, which localizes to stress granules under conditions of stress. The LCD of hnRNPA1 is sufficient for mediating phase separation in vitro. However, the stimulus-responsive phase behavior of a number of domain deletion constructs suggests that the folded RRM domains contribute to phase separation, even in the absence of RNA. Small-angle X-ray scattering experiments show that hnRNPA1 adopts compact conformations at low ionic strength, that the protein expands considerably with increasing ionic strength, and that it reaches a maximal plateau at 300 mM NaCl. These data point to electrostatically mediated interactions that compact hnRNPA1. NMR experiments and coarse-grained MD simulations showed that the LCD interacts transiently with the RRMs, providing a mechanistic explanation for the observed stimulus-responsiveness of phase separation. Disordered and folded domains that have evolved together likely encode a multitude of interactions that can modify and regulate phase separation.hnRNPA1 phase separation is highly salt sensitive LCD-LCD interactions can mediate phase separation over a wide range of NaCl concentrations. At low NaCl concentrations, electrostatic RRM-LCD interactions occur and can contribute positively to phase separation, but they are screened at high NaCl concentrations. The folded domains solubilize hnRNPA1 under these conditions and prevent phase separation.Competing Interest StatementT.M. is a consultant for Small Molecule RNA Co.