title: Cell-free formation of RNA granules: low complexity sequence domains form dynamic fibers within hydrogels.
abstract: Eukaryotic cells contain assemblies of RNAs and proteins termed RNA granules. Many proteins within these bodies contain KH or RRM RNA-binding domains as well as low complexity (LC) sequences of unknown function. We discovered that exposure of cell or tissue lysates to a biotinylated isoxazole (b-isox) chemical precipitated hundreds of RNA-binding proteins with significant overlap to the constituents of RNA granules. The LC sequences within these proteins are both necessary and sufficient for b-isox-mediated aggregation, and these domains can undergo a concentration-dependent phase transition to a hydrogel-like state in the absence of the chemical. X-ray diffraction and EM studies revealed the hydrogels to be composed of uniformly polymerized amyloid-like fibers. Unlike pathogenic fibers, the LC sequence-based polymers described here are dynamic and accommodate heterotypic polymerization. These observations offer a framework for understanding the function of LC sequences as well as an organizing principle for cellular structures that are not membrane bound.
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, 75390-9152, USA.
authors.forename: Masato
authors.initials: M
authors.lastname: Kato
authors.forename: Tina W
authors.initials: TW
authors.lastname: Han
authors.forename: Shanhai
authors.initials: S
authors.lastname: Xie
authors.forename: Kevin
authors.initials: K
authors.lastname: Shi
authors.forename: Xinlin
authors.initials: X
authors.lastname: Du
authors.forename: Leeju C
authors.initials: LC
authors.lastname: Wu
authors.forename: Hamid
authors.initials: H
authors.lastname: Mirzaei
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Goldsmith
authors.forename: Jamie
authors.initials: J
authors.lastname: Longgood
authors.forename: Jimin
authors.initials: J
authors.lastname: Pei
authors.forename: Nick V
authors.initials: NV
authors.lastname: Grishin
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Frantz
authors.forename: Jay W
authors.initials: JW
authors.lastname: Schneider
authors.forename: She
authors.initials: S
authors.lastname: Chen
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.forename: Michael R
authors.initials: MR
authors.lastname: Sawaya
authors.forename: David
authors.initials: D
authors.lastname: Eisenberg
authors.forename: Robert
authors.initials: R
authors.lastname: Tycko
authors.forename: Steven L
authors.initials: SL
authors.lastname: McKnight
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism; D017173:Caenorhabditis elegans / Q000166:cytology / Q000378:metabolism; D002474:Cell-Free System; D003594:Cytoplasmic Granules / Q000737:chemistry / Q000378:metabolism*; D053595:Embryonic Stem Cells / Q000378:metabolism; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000378:metabolism*; D008297:Male; D051379:Mice; D008958:Models, Molecular; D041681:NIH 3T3 Cells; D012313:RNA / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D013737:Testis / Q000166:cytology / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D016601:RNA-Binding Proteins; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D012313:RNA