Osmosensing and osmoregulatory compatible solute accumulation by bacteria

Wood, Janet M.; Bremer, Erhard; Csonka, László N.; Kraemer, Reinhard; Poolman, Bert; Heide, T. van der; Smith, Linda Tombras

doi:10.1016/s1095-6433(01)00442-1

Cited by 412 publications

(374 citation statements)

References 94 publications

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“…Increased osmolality of the nutrient medium triggers an osmotic shock response, and the cell starts to increase the cytoplasmic concentration of small protective organic molecules, termed osmolytes, which counteract the loss of water and protect cellular proteins from denaturation. [19][20][21] Both active transport of exogenous osmolytes and synthesis of endogenous osmolytes are deployed to accomplish the increase in intracellular concentrations. The intracellular amount of the osmolyte (here proline 15 ) depends on the salinity of the external medium and can reach concentrations >0.4M by 0.3M NaCl.…”

Section: Review Of Our In Vivo Folding and Aggregation Studiesmentioning

confidence: 99%

From the test tube to the cell: Exploring the folding and aggregation of a β‐clam protein

Ignatova¹,

Krishnan²,

Bombardier³

et al. 2007

Biopolymers

107

126

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A crucial challenge in present biomedical research is the elucidation of how fundamental processes like protein folding and aggregation occur in the complex environment of the cell. Many new physico‐chemical factors like crowding and confinement must be considered, and immense technical hurdles must be overcome in order to explore these processes in vivo. Understanding protein misfolding and aggregation diseases and developing therapeutic strategies to these diseases demand that we gain mechanistic insight into behaviors and misbehaviors of proteins as they fold in vivo. We have developed a fluorescence approach using FlAsH labeling to study the thermodynamics of folding of a model β‐rich protein, cellular retinoic acid binding protein (CRABP) in Escherichia coli cells. The labeling approach has also enabled us to follow aggregation of a modified version of CRABP and chimeras between CRABP and huntingtin exon 1 with its glutamine repeat tract. In this article, we review our recent results using FlAsH labeling to study in‐vivo folding and present new observations that hint at fundamental differences between the thermodynamics and kinetics of protein folding in vivo and in vitro. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 157–163, 2007. This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

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Section: Review Of Our In Vivo Folding and Aggregation Studiesmentioning

confidence: 99%

From the test tube to the cell: Exploring the folding and aggregation of a β‐clam protein

Ignatova¹,

Krishnan²,

Bombardier³

et al. 2007

Biopolymers

107

126

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“…We show that this results in a considerable delay of the response of cells to osmotic shocks, and to an extreme cell-to-cell stochastic variations in their response times, despite the large numbers of channels present in each cell. We discuss how our results are relevant for E. coli.Abrupt changes in the osmolarity of the environment is a hazard most organisms are subject to at one time or another [1][2][3][4][5][6]. A sudden drop in osmolarity (an osmotic shock ) will cause water to rush into a living cell, and requires an immediate response by the cell to prevent it from getting damaged or undergoing lysis from the increased tension on the cellular membrane.…”

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confidence: 99%

Cooperative response and clustering: Consequences of membrane-mediated interactions among mechanosensitive channels

2017

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Mechanosensitive (MS) channels are ion channels which act as cells' safety valves, opening when the osmotic pressure becomes too high and making cells avoid damage by releasing ions. They are found on the cellular membrane of a large number of organisms. They interact with each other by means of deformations they induce in the membrane. We show that collective dynamics arising from the inter-channel interactions lead to first and second-order phase transitions in the fraction of open channels in equilibrium relating to the formation of channel clusters. We show that this results in a considerable delay of the response of cells to osmotic shocks, and to an extreme cell-to-cell stochastic variations in their response times, despite the large numbers of channels present in each cell. We discuss how our results are relevant for E. coli.Abrupt changes in the osmolarity of the environment is a hazard most organisms are subject to at one time or another [1][2][3][4][5][6]. A sudden drop in osmolarity (an osmotic shock ) will cause water to rush into a living cell, and requires an immediate response by the cell to prevent it from getting damaged or undergoing lysis from the increased tension on the cellular membrane. Mechanosensitive channels (or MS channels) are ion channels located on the cell membrane, which open when the membrane tension becomes too high [7,8], and play a crucial role in the cell's defence mechanism against osmotic shocks [9,10]. They act as safety valves, releasing ions and decreasing the osmotic pressure and the membrane tension. Mechanosensitive channels are found in many organisms, and have been well characterised in the bacterium E. coli [11-13].The cellular membrane in which the mechanosensitive channels are inserted is a lipid bilayer. The interior of the bilayer is hydrophobic, making it energetically favourable for it to thicken or compress to match the hydrophobic parts of the channel proteins inserted in the membrane [14]. This results in a deformation profile around each channel, with the thickness of the bilayer being a function of position. This deformation mediates a shortrange effective force between two neighbouring channels, similar to the force between two nearby corks floating on water, which interact through the deformation they induce on the surface of water. This interaction can be attractive or repulsive, depending on the shapes of the two molecules. Furthermore, a theoretical analysis suggests that the interaction between two neighbouring channels lowers the tension needed to open them during an osmotic shock [15], raising the possibility that their function could be influenced by their spatial distribution on the membrane (as already noticed for other membrane proteins [16,17]). This is reinforced by the fact that the channels' attractive forces suggest that they may agglomerate into clusters. Our goal in this paper is to determine the consequences that the inter-channel interaction has on the dynamics of this system, focusing in particular on channel clustering and its con...

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“…For example, in Escherichia coli, ProP is activated by hypertonicity and mediates uptake of compatible solutes such as proline, glycine betaine, and ectoine (6). Plants accumulate proline through hypertonicity-induced expression of biosynthetic enzymes (7).…”

mentioning

confidence: 99%

Genome-wide RNAi screening identifies protein damage as a regulator of osmoprotective gene expression

Lamitina

Huang²,

Strange³

2006

Proc. Natl. Acad. Sci. U.S.A.

163

257

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The detection, stabilization, and repair of stress-induced damage are essential requirements for cellular life. All cells respond to osmotic stress-induced water loss with increased expression of genes that mediate accumulation of organic osmolytes, solutes that function as chemical chaperones and restore osmotic homeostasis. The signals and signaling mechanisms that regulate osmoprotective gene expression in animal cells are poorly understood. Here, we show that gpdh-1 and gpdh-2, genes that mediate the accumulation of the organic osmolyte glycerol, are essential for survival of the nematode Caenorhabditis elegans during osmotic stress. Expression of GFP driven by the gpdh-1 promoter (P gpdh-1::GFP) is detected only during hypertonic stress but is not induced by other stressors. Using Pgpdh-1::GFP expression as a phenotype, we screened Ϸ16,000 genes by RNAi feeding and identified 122 that cause constitutive activation of gpdh-1 expression and glycerol accumulation. Many of these genes function to regulate protein translation and cotranslational protein folding and to target and degrade denatured proteins, suggesting that the accumulation of misfolded proteins functions as a signal to activate osmoprotective gene expression and organic osmolyte accumulation in animal cells. Consistent with this hypothesis, 73% of these protein-homeostasis genes have been shown to slow age-dependent protein aggregation in C. elegans. Because diverse environmental stressors and numerous disease states result in protein misfolding, mechanisms must exist that discriminate between osmotically induced and other forms of stress-induced protein damage. Our findings provide a foundation for understanding how these damage-selectivity mechanisms function.Caenorhabditis elegans ͉ functional genomics ͉ organic osmolytes ͉ osmotic stress

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Osmosensing and osmoregulatory compatible solute accumulation by bacteria

Cited by 412 publications

References 94 publications

From the test tube to the cell: Exploring the folding and aggregation of a β‐clam protein

From the test tube to the cell: Exploring the folding and aggregation of a β‐clam protein

Cooperative response and clustering: Consequences of membrane-mediated interactions among mechanosensitive channels

Genome-wide RNAi screening identifies protein damage as a regulator of osmoprotective gene expression

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