Multivalent Proteins Rapidly and Reversibly Phase-Separate upon Osmotic Cell Volume Change

Jalihal, Ameya P.; Pitchiaya, Sethuramasundaram; Xiao, Lanbo; Bawa, Pushpinder; Jiang, Xia; Bedi, Karan; Parolia, Abhijit; Cieślik, Marcin; Ljungman, Mats; Chinnaiyan, Arul M.; Walter, Nils G.

doi:10.1016/j.molcel.2020.08.004

Cited by 88 publications

(80 citation statements)

References 78 publications

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“…Disrupting any of these key interactions driving phase separation is expected to interfere with the phase separation potential of a system. Consistent with this expectation, posttranslational modifications such as phosphorylation and methylation have been found to modulate condensation responses ( 46 , 47 , 48 , 49 ) ( Fig. 1 B ).…”

Section: Physicochemical Underpinnings Of Phase Separationsupporting

confidence: 73%

“…We reported in Jalihal, Pitchiaya et al. ( 49 ) that a significant fraction of the mammalian proteome responds very rapidly, on the order of 10 s, to osmotic cell volume shrinkage by reversibly forming a large number of small “HOPS” condensates. Unlike other constitutively present or stress-induced condensates, which are known to be driven by disordered protein regions, HOPS is predominantly associated with structured homomeric self-interaction domains of proteins, embedded in a significant fraction of the proteome.…”

Section: Osmotic Perturbations and The Hyperosmotic Phase Separation mentioning

confidence: 92%

“…Studying phase separation from purified components in the test tube allows precise and systematic investigation of the effects of composition, temperature, pH, salt, etc., to build a phase diagram ( 133 , 134 , 135 ). While such manipulations are less easily achieved in cells, several recent studies have reported strategies to obtain phase transition information from intracellular fluorescence measurements ( 42 , 43 , 49 , 78 ). 4.…”

Section: Physicochemical Underpinnings Of Phase Separationmentioning

confidence: 99%

“…, suggests that cellular response by condensation may also occur much more rapidly, at the timescale of seconds ( 49 , 91 ). In addition to being ubiquitous and extremely rapid, sustained HOPS influences translation of mRNA targets of microRNAs ( 69 ) and impacts cleavage and polyadenylation of nascent transcripts ( 49 ), among other gene regulatory processes ( 92 ).…”

Section: Osmotic Perturbations and The Hyperosmotic Phase Separation mentioning

confidence: 99%

“…Hyperosmolarity exceeding the physiological osmotic range of 285 to 295 mOsm/kg leads to loss of intracellular water through aquaporin channels, manifesting as rapid changes in cell shape and volume across a wide range of tissue types ( 49 , 93 , 94 ). Prolonged exposure to high levels of osmolarity can adversely affect protein structure and lead to DNA damage ( 95 ), with long-term exposure leading to cell death by apoptosis and drastic consequences at the organismal level ( 96 ).…”

Section: Osmotic Perturbations and The Hyperosmotic Phase Separation mentioning

confidence: 99%

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Hyperosmotic phase separation: Condensates beyond inclusions, granules and organelles

Jalihal

Schmidt

Gao

et al. 2021

Journal of Biological Chemistry

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Biological liquid-liquid phase separation has gained considerable attention in recent years as a driving force for the assembly of subcellular compartments termed membraneless organelles. The field has made great strides in elucidating the molecular basis of biomolecular phase separation in various disease, stress-response and developmental contexts. Many important biological consequences of such “condensation” are now emerging from in vivo studies. Here we review recent work from our group and others showing that many proteins undergo rapid, reversible condensation in the cellular response to ubiquitous environmental fluctuations such as osmotic changes. We discuss molecular crowding as an important driver of condensation in these responses and suggest that a significant fraction of the proteome is poised to undergo phase separation under physiological conditions. In addition, we review methods currently emerging to visualize, quantify and modulate the dynamics of intracellular condensates in live cells. Finally, we propose a metaphor for rapid phase separation based on cloud formation, reasoning that our familiar experiences with the readily reversible condensation of water droplets help understand the principle of phase separation. Overall, we provide an account of how biological phase separation supports the highly intertwined relationship between the composition and dynamic internal organization of cells, thus facilitating extremely rapid reorganization in response to internal and external fluctuations.

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Section: Physicochemical Underpinnings Of Phase Separationsupporting

confidence: 73%

Section: Osmotic Perturbations and The Hyperosmotic Phase Separation mentioning

confidence: 92%

Section: Physicochemical Underpinnings Of Phase Separationmentioning

confidence: 99%

Section: Osmotic Perturbations and The Hyperosmotic Phase Separation mentioning

confidence: 99%

Section: Osmotic Perturbations and The Hyperosmotic Phase Separation mentioning

confidence: 99%

See 3 more Smart Citations

Hyperosmotic phase separation: Condensates beyond inclusions, granules and organelles

Jalihal

Schmidt

Gao

et al. 2021

Journal of Biological Chemistry

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Protein Condensation, Cellular Organization, and Spatiotemporal Regulation of Cytoplasmic Properties

Tartwijk

Kaminski

2022

Advanced Biology

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These folds are determined by both protein sequence and solvent properties, and determine protein function. [2] Therefore, the diversity of protein folds in cells allows them to carry out a range of functions, such as catalysis of different reactions. Functional versatility within polypeptide chains is further increased through the presence of multiple independently folding sequences, defined as domains, each associated with distinct functions, such as dimerization or responsiveness to a regulator. However, it is now recognized that some proteins do not have defined conformations, or feature domains that are intrinsically disordered (intrinsically disordered regions, IDRs), and that these confer function by mediating context-dependent proteinprotein interactions. [3] The concept of self-organization of proteins is also applied to assemblies of multiple proteins, in which case it refers to formation of dynamic multi-component structures, [4] including certain oligomeric complexes, filaments, and phase-separated assemblies. In phase-separated assemblies, of which a range exist, IDR-containing proteins form a dense phase within the cytoplasm, commonly referred to as biomolecular condensates. [5] As for folds, the formation of these assemblies depends both on interactions between the phase-separating proteins, which can be mediated by their IDRs, and between these proteins and the surrounding solution. Within the cytoplasm, these phase-separated "droplets" commonly contain RNA, in which case they are referred to as ribonucleoprotein (RNP) granules. They can be considered to have "emergent properties:" certain characteristics can be ascribed to assemblies that are not properties of individual constituent proteins. [6] For instance, biomolecular condensates can display liquid-like properties such as fusion and wetting, which led to their identification as phase-separated droplets. [7] These properties allow them to function as dynamic membraneless organelles, or compartments. This compartmentalization is commonly referred to as occurring on the "mesoscale," which is defined as that range of lengths larger than the size of individual molecular machinery such as ribosomes, but smaller than that of the whole cell. [8] The sensitivity of protein folds and macromolecular interactions to local environmental conditions confers both regulatory potential and risk of loss of function in "extreme" conditions. This regulatory potential is exemplified by and has beenThe cytoplasm is an aqueous, highly crowded solution of active macromolecules. Its properties influence the behavior of proteins, including their folding, motion, and interactions. In particular, proteins in the cytoplasm can interact to form phase-separated assemblies, so-called biomolecular condensates. The interplay between cytoplasmic properties and protein condensation is critical in a number of functional contexts and is the subject of this review. The authors first describe how cytoplasmic properties can affect protein behavior, in particular condensate formation...

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Control of Enzyme Reactivity in Response to Osmotic Pressure Modulation Mimicking Dynamic Assembly of Intracellular Organelles

et al. 2023

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In response to variations in osmotic stress, in particular to hypertonicity associated with biological dysregulations, cells have developed complex mechanisms to release their excess water, thus avoiding their bursting and death. When water is expelled, cells shrink and concentrate their internal bio(macro)molecular content, inducing the formation of membraneless organelles following a liquid–liquid phase separation (LLPS) mechanism. To mimic this intrinsic property of cells, functional thermo‐responsive elastin‐like polypeptide (ELP) biomacromolecular conjugates are herein encapsulated into self‐assembled lipid vesicles using a microfluidic system, together with polyethylene glycol (PEG) to mimic cells’ interior crowded microenvironment. By inducing a hypertonic shock onto the vesicles, expelled water induces a local increase in concentration and a concomitant decrease in the cloud point temperature (Tcp) of ELP bioconjugates that phase separate and form coacervates mimicking cellular stress‐induced membraneless organelle assemblies. Horseradish peroxidase (HRP), as a model enzyme, is bioconjugated to ELPs and is locally confined in coacervates as a response to osmotic stress. This consequently increases local HRP and substrate concentrations and accelerates the kinetics of the enzymatic reaction. These results illustrate a unique way to fine‐tune enzymatic reactions dynamically as a response to a physiological change in isothermal conditions.

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Multivalent Proteins Rapidly and Reversibly Phase-Separate upon Osmotic Cell Volume Change

Cited by 88 publications

References 78 publications

Hyperosmotic phase separation: Condensates beyond inclusions, granules and organelles

Hyperosmotic phase separation: Condensates beyond inclusions, granules and organelles

Protein Condensation, Cellular Organization, and Spatiotemporal Regulation of Cytoplasmic Properties

Control of Enzyme Reactivity in Response to Osmotic Pressure Modulation Mimicking Dynamic Assembly of Intracellular Organelles

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