Dynamic protein-rich intracellular structures that contain phase-separated intrinsically disordered proteins (IDPs) composed of sequences of low complexity (SLC) have been shown to serve a variety of important cellular functions, which include signalling, compartmentalization and stabilization. However, our understanding of these structures and our ability to synthesize models of them have been limited. We present design rules for IDPs possessing SLCs that phase separate into diverse assemblies within droplet microenvironments. Using theoretical analyses, we interpret the phase behaviour of archetypal IDP sequences and demonstrate the rational design of a vast library of multicomponent protein-rich structures that ranges from uniform nano-, meso- and microscale puncta (distinct protein droplets) to multilayered orthogonally phase-separated granular structures. The ability to predict and program IDP-rich assemblies in this fashion offers new insights into (1) genetic-to-molecular-to-macroscale relationships that encode hierarchical IDP assemblies, (2) design rules of such assemblies in cell biology and (3) molecular-level engineering of self-assembled recombinant IDP-rich materials.
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We are grateful for support from the National Science Foundation (NSF) Research Triangle MRSEC (DMR-1121107), Pratt–Gardner Fellowship (J.R.S.), Medtronic Inc. Fellowship in Biomedical Engineering (J.R.S.) and the NSF Graduate Research Fellowship Program (DGF1106401) (J.R.S.). A.C. acknowledges the support of the National Institutes of Health (NIH) though grants R01-GM61232, R01-EB000188 and R01-EB007205. M.R. acknowledges financial support from the NSF under grants DMR-1309892 and DMR-1436201, the NIH under grants P01-HL108808 and 1UH2HL123645, and the Cystic Fibrosis Foundation. We thank J. McDaniel, S. MacEwan and J. Genzer for their helpful discussions and for providing some of the plasmids containing genes that encode the ELPs used in this study. We also thank the Duke Light Core Microscopy Facility for fruitful discussions and help with confocal microscopy experiments.
The authors declare no competing financial interests.
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Simon, J., Carroll, N., Rubinstein, M. et al. Programming molecular self-assembly of intrinsically disordered proteins containing sequences of low complexity. Nature Chem 9, 509–515 (2017). https://doi.org/10.1038/nchem.2715
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