RNA-Based Coacervates as a Model for Membraneless Organelles: Formation, Properties, and Interfacial Liposome Assembly.
Liquid-liquid phase separation is responsible for formation of P granules, nucleoli, and other membraneless subcellular organelles composed of RNA and proteins. Efforts to understand the physical basis of liquid organelle formation have thus far focused on intrinsically disordered proteins (IDPs) as major components that dictate occurrence and properties. Here, we show that complex coacervates composed of low complexity RNA (polyuridylic acid, polyU) and short polyamines (spermine and spermidine) share many features of IDP-based coacervates. PolyU/polyamine coacervates compartmentalize biomolecules (peptides, oligonucleotides) in a sequence- and length-dependent manner. These solutes retain mobility within the coacervate droplets, as demonstrated by rapid recovery from photobleaching. Coacervation is reversible with changes in solution temperature due to changes in the polyU structure that impact its interactions with polyamines. We further demonstrate that lipid vesicles assemble at the droplet interface without impeding RNA entry/egress. These vesicles remain intact at the interface and can be released upon temperature-induced droplet dissolution.
Department of Chemistry, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
William M
WM
Aumiller
Department of Chemistry, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Fatma
F
Pir Cakmak
Department of Chemistry, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Bradley W
BW
Davis
Department of Chemistry, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Christine D
CD
Keating
D000595:Amino Acid Sequence; D058045:Artificial Cells; D036681:Fluorescence Recovery After Photobleaching; D020404:Glycerophospholipids / Q000737:chemistry; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D044367:Phase Transition; D012313:RNA / Q000737:chemistry*; D013095:Spermidine / Q000737:chemistry*; D013096:Spermine / Q000737:chemistry*; D044366:Transition Temperature; D053835:Unilamellar Liposomes / Q000737:chemistry*
D020404:Glycerophospholipids; D009843:Oligoribonucleotides; D010455:Peptides; D053835:Unilamellar Liposomes; D013096:Spermine; D012313:RNA; D013095:Spermidine