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Essmann CL, Elmi M, Rekatsinas C, Chrysochoidis N, Shaw M, Pawar V, Srinivasan MA, Vavourakis V. The influence of internal pressure and neuromuscular agents on C. elegans biomechanics: an empirical and multi-compartmental in silico modelling study. Front Bioeng Biotechnol 2024; 12:1335788. [PMID: 38558792 PMCID: PMC10978802 DOI: 10.3389/fbioe.2024.1335788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/20/2024] [Indexed: 04/04/2024] Open
Abstract
The function of a specific tissue and its biomechanics are interdependent, with pathologies or ageing often being intertwined with structural decline. The biomechanics of Caenorhabditis elegans, a model organism widely used in pharmacological and ageing research, has been established as biomarker for healthy ageing. However, the properties of the constituent tissues, and their contribution to the overall mechanical characteristics of the organism, remain relatively unknown. In this study we investigated the biomechanics of healthy C. elegans cuticle, muscle tissue, and pseudocoelom using a combination of indentation experiments and in silico modelling. We performed stiffness measurements using an atomic force microscope. To approximate the nematode's cylindrical body we used a novel three-compartment nonlinear finite element model, enabling us to analyse of how changes in the elasticity of individual compartments affect the bulk stiffness. We then fine-tuned the parameters of the model to match the simulation force-indentation output to the experimental data. To test the finite element model, we modified distinct compartments experimentally. Our in silico results, in agreement with previous studies, suggest that hyperosmotic shock reduces stiffness by decreasing the internal pressure. Unexpectedly, treatment with the neuromuscular agent aldicarb, traditionally associated with muscle contraction, reduced stiffness by decreasing the internal pressure. Furthermore, our finite element model can offer insights into how drugs, mutations, or processes such as ageing target individual tissues.
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Affiliation(s)
- Clara L. Essmann
- Department of Bioinformatics and Molecular Genetics, University of Freiburg, Freiburg, Baden-Wuerttemberg, Germany
- Department of Computer Science, University College London, London, United Kingdom
| | - Muna Elmi
- Department of Computer Science, University College London, London, United Kingdom
| | | | - Nikolaos Chrysochoidis
- Department of Mechanical Engineering and Aeronautics, University of Patras, Patras, Greece
| | - Michael Shaw
- Department of Computer Science, University College London, London, United Kingdom
- National Physical Laboratory, Teddington, United Kingdom
| | - Vijay Pawar
- Department of Computer Science, University College London, London, United Kingdom
| | | | - Vasileios Vavourakis
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
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Woudstra C, Brøndsted L. Producing Tailocins from Phages Using Osmotic Shock and Benzalkonium Chloride. Phage (New Rochelle) 2023; 4:136-140. [PMID: 37841391 PMCID: PMC10574523 DOI: 10.1089/phage.2023.0014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
In the light of the worldwide antimicrobial resistance crisis, new substitutes to antibiotics are urgently needed. Tailocins or phage tail-like bacteriocin particles, produced by bacteria for environmental competition, are a potential antimicrobial alternative to antibiotic treatment. Yet, the availability of characterized Tailocins is limited. We explored the possibility to produce new Tailocins from phage particles, using osmotic shock or chemical treatment by the ammonium quaternary compound benzalkonium chloride on Ackermannviridae phage S117 and using Straboviridae phage T4 as control. We report that phage S117 was resistant to such treatment, while successful production of Tailocins by osmotic shock was achieved for phage T4. Finally, chemical treatment with benzalkonium chloride was inefficient on phage S117 but successfully inactivated phage T4 without production of Tailocins. Further studies are needed to implement such treatments of phages for producing Tailocins with killing activity.
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Affiliation(s)
- Cedric Woudstra
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Lone Brøndsted
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
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Conq J, Joudiou N, Ucakar B, Vanvarenberg K, Préat V, Gallez B. Assessment of Hyperosmolar Blood-Brain Barrier Opening in Glioblastoma via Histology with Evans Blue and DCE-MRI. Biomedicines 2023; 11:1957. [PMID: 37509598 PMCID: PMC10377677 DOI: 10.3390/biomedicines11071957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/02/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND While the blood-brain barrier (BBB) is often compromised in glioblastoma (GB), the perfusion and consequent delivery of drugs are highly heterogeneous. Moreover, the accessibility of drugs is largely impaired in the margins of the tumor and for infiltrating cells at the origin of tumor recurrence. In this work, we evaluate the value of methods to assess hemodynamic changes induced by a hyperosmolar shock in the core and the margins of a tumor in a GB model. METHODS Osmotic shock was induced with an intracarotid infusion of a hypertonic solution of mannitol in mice grafted with U87-MG cells. The distribution of fluorescent dye (Evans blue) within the brain was assessed via histology. Dynamic contrast-enhanced (DCE)-MRI with an injection of Gadolinium-DOTA as the contrast agent was also used to evaluate the effect on hemodynamic parameters and the diffusion of the contrast agent outside of the tumor area. RESULTS The histological study revealed that the fluorescent dye diffused much more largely outside of the tumor area after osmotic shock than in control tumors. However, the study of tumor hemodynamic parameters via DCE-MRI did not reveal any change in the permeability of the BBB, whatever the studied MRI parameter. CONCLUSIONS The use of hypertonic mannitol infusion seems to be a promising method to increase the delivery of compounds in the margins of GB. Nevertheless, the DCE-MRI analysis method using gadolinium-DOTA as a contrast agent seems of limited value for determining the efficacy of opening the BBB in GB after osmotic shock.
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Affiliation(s)
- Jérôme Conq
- UCLouvain, Louvain Drug Research Institute (LDRI), Biomedical Magnetic Resonance Research Group, 1200 Brussels, Belgium
- UCLouvain, Louvain Drug Research Institute (LDRI), Advanced Drug Delivery and Biomaterials Research Group, 1200 Brussels, Belgium
| | - Nicolas Joudiou
- UCLouvain, Louvain Drug Research Institute (LDRI), Nuclear and Electron Spin Technologies (NEST) Platform, 1200 Brussels, Belgium
| | - Bernard Ucakar
- UCLouvain, Louvain Drug Research Institute (LDRI), Advanced Drug Delivery and Biomaterials Research Group, 1200 Brussels, Belgium
| | - Kevin Vanvarenberg
- UCLouvain, Louvain Drug Research Institute (LDRI), Advanced Drug Delivery and Biomaterials Research Group, 1200 Brussels, Belgium
| | - Véronique Préat
- UCLouvain, Louvain Drug Research Institute (LDRI), Advanced Drug Delivery and Biomaterials Research Group, 1200 Brussels, Belgium
| | - Bernard Gallez
- UCLouvain, Louvain Drug Research Institute (LDRI), Biomedical Magnetic Resonance Research Group, 1200 Brussels, Belgium
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4
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Labuz EC, Footer MJ, Theriot JA. Confined keratocytes mimic in vivo migration and reveal volume-speed relationship. Cytoskeleton (Hoboken) 2023; 80:34-51. [PMID: 36576104 DOI: 10.1002/cm.21741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 12/07/2022] [Accepted: 12/26/2022] [Indexed: 12/29/2022]
Abstract
Fish basal epidermal cells, known as keratocytes, are well-suited for cell migration studies. In vitro, isolated keratocytes adopt a stereotyped shape with a large fan-shaped lamellipodium and a nearly spherical cell body. However, in their native in vivo environment, these cells adopt a significantly different shape during their rapid migration toward wounds. Within the epidermis, keratocytes experience two-dimensional (2D) confinement between the outer epidermal cell layer and the basement membrane; these two deformable surfaces constrain keratocyte cell bodies to be flatter in vivo than in isolation. In vivo keratocytes also exhibit a relative elongation of the front-to-back axis and substantially more lamellipodial ruffling, as compared to isolated cells. We have explored the effects of 2D confinement, separated from other in vivo environmental cues, by overlaying isolated cells with an agarose hydrogel with occasional spacers, or with a ceiling made of polydimethylsiloxane (PDMS) elastomer. Under these conditions, isolated keratocytes more closely resemble the in vivo migratory shape phenotype, displaying a flatter apical-basal axis and a longer front-to-back axis than unconfined keratocytes. We propose that 2D confinement contributes to multiple dimensions of in vivo keratocyte shape determination. Further analysis demonstrates that confinement causes a synchronous 20% decrease in both cell speed and volume. Interestingly, we were able to replicate the 20% decrease in speed using a sorbitol hypertonic shock to shrink the cell volume, which did not affect other aspects of cell shape. Collectively, our results suggest that environmentally imposed changes in cell volume may influence cell migration speed, potentially by perturbing physical properties of the cytoplasm.
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Affiliation(s)
- Ellen C Labuz
- Biophysics Program, Stanford University, Stanford, California, USA.,Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, Washington, USA
| | - Matthew J Footer
- Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, Washington, USA
| | - Julie A Theriot
- Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, Washington, USA
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Nikolac Gabaj N, Miler M, Vrtaric A, Celap I, Bocan M, Filipi P, Radisic Biljak V, Simundic AM, Supak Smolcic V, Kocijancic M. Comparison of three different protocols for obtaining hemolysis. Clin Chem Lab Med 2022; 60:714-725. [PMID: 35212494 DOI: 10.1515/cclm-2021-1227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/11/2022] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Hemolysis is associated with erroneous or delayed results. Objectives of the study were to compare four different methods for obtaining hemolysis in vitro on three different analyzers. METHODS Hemolysis was prepared with addition of pure hemoglobin into serum pool, osmotic shock, aspiration through blood collection needle, freezing/thawing of whole blood. Biochemistry parameters were measured in duplicate at Architect c8000 (Abbott, Abbott Park, USA), Beckman Coulter AU680 (Beckman Coulter, Brea, USA) and Cobas 6000 c501 (Roche, Mannheim, Germany), according to manufacturers' declarations. Cut-off value was defined as the highest value of H index with corresponding bias lower than acceptance criteria. RESULTS We were not able to obtain results with freezing protocol. On all three platforms, lowest number of analytes were sensitive to hemolysis at H=0.5 using method of adding free hemoglobin. When osmotic shock was used, cut-off values for the most analytes were generally met at lower values. Hemolysis significantly interfered with measurement of potassium and lactate dehydrogenase (LD) at H=0.5 on all platforms. The most of the tested analytes had the lowest acceptable H index when aspiration method was used. At the low level of hemolysis (H=0.8) glucose, sodium, potassium, chloride, phosphate, and LD were affected on all analyzers, with some additional analytes depending on the manufacturer. CONCLUSIONS Hemolysis interference differs on different analyzers and according to protocol for obtaining hemolysis. Aspiration method was generally the most sensitive to hemolysis interference, while addition of free Hb was the most resistant.
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Affiliation(s)
- Nora Nikolac Gabaj
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Department of Clinical Chemistry, Sestre milosrdnice University Hospital Center, Zagreb, Croatia
- Faculty of Pharmacy and Biochemistry, University of Zagreb, Zagreb, Croatia
| | - Marijana Miler
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Department of Clinical Chemistry, Sestre milosrdnice University Hospital Center, Zagreb, Croatia
| | - Alen Vrtaric
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Department of Clinical Chemistry, Sestre milosrdnice University Hospital Center, Zagreb, Croatia
| | - Ivana Celap
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Department of Clinical Chemistry, Sestre milosrdnice University Hospital Center, Zagreb, Croatia
| | - Marina Bocan
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Medical Biochemistry Laboratory, Polyclinic Salzer, Zagreb, Croatia
| | - Petra Filipi
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Department of Medical Laboratory Diagnostics, University Hospital Centre Split, Split, Croatia
| | - Vanja Radisic Biljak
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Department of Medical Laboratory Diagnostics, University Hospital "Sveti Duh", Zagreb, Croatia
| | - Ana-Maria Simundic
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Faculty of Pharmacy and Biochemistry, University of Zagreb, Zagreb, Croatia
- Department of Medical Laboratory Diagnostics, University Hospital "Sveti Duh", Zagreb, Croatia
| | - Vesna Supak Smolcic
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Clinical Department of Laboratory Diagnostics, Clinical Hospital Center Rijeka, Rijeka, Croatia
- Department of Medical Informatics, Rijeka University School of Medicine, Rijeka, Croatia
| | - Marija Kocijancic
- Working Group for Preanalytical Phase of the Croatian Society of Medical Biochemistry and Laboratory Medicine, Zagreb, Croatia
- Department of Laboratory Medicine, Central Laboratory, University Clinic Halle, Halle, Germany
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Ianutsevich EA, Danilova OA, Bondarenko SA, Tereshina VM. Membrane lipid and osmolyte readjustment in the alkaliphilic micromycete Sodiomyces tronii under cold, heat and osmotic shocks. Microbiology (Reading) 2021; 167. [PMID: 34816793 DOI: 10.1099/mic.0.001112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Previously, we showed for the first time that alkaliphilic fungi, in contrast to alkalitolerant fungi, accumulated trehalose under extremely alkaline conditions, and we have proposed its key role in alkaliphilia. We propose that high levels of trehalose in the mycelium of alkaliphiles may promote adaptation not only to alkaline conditions, but also to other stressors. Therefore, we studied changes in the composition of osmolytes, and storage and membrane lipids under the action of cold (CS), heat (HS) and osmotic (OS) shocks in the obligate alkaliphilic micromycete Sodiomyces tronii. During adaptation to CS, an increase in the degree of unsaturation of phospholipids was observed while the composition of osmolytes, membrane and storage lipids remained the same. Under HS conditions, a twofold increase in the level of trehalose and an increase in the proportion of phosphatidylethanolamines were observed against the background of a decrease in the proportion of phosphatidic acids. OS was accompanied by a decrease in the amount of membrane lipids, while their ratio remained unchanged, and an increase in the level of polyols (arabitol and mannitol) in the fungal mycelium, which suggests their role for adaptation to OS. Thus, the observed consistency of the composition of membrane lipids suggests that trehalose can participate in adaptation not only to extremely alkaline conditions, but also to other stressors - HS, CS and OS. Taken together, the data obtained indicate the adaptability of the fungus to the action of various stressors, which can point to polyextremotolerance.
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Affiliation(s)
- Elena A Ianutsevich
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Olga A Danilova
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Sofiya A Bondarenko
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia.,Lomonosov Moscow State University, Faculty of Biology, Russia
| | - Vera M Tereshina
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
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Rodríguez-Pupo EC, Pérez-Llano Y, Tinoco-Valencia JR, Sánchez NS, Padilla-Garfias F, Calahorra M, Sánchez NDC, Sánchez-Reyes A, Rodríguez-Hernández MDR, Peña A, Sánchez O, Aguirre J, Batista-García RA, Folch-Mallol JL, Sánchez-Carbente MDR. Osmolyte Signatures for the Protection of Aspergillus sydowii Cells under Halophilic Conditions and Osmotic Shock. J Fungi (Basel) 2021; 7:414. [PMID: 34073303 PMCID: PMC8228332 DOI: 10.3390/jof7060414] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/11/2021] [Accepted: 05/20/2021] [Indexed: 11/16/2022] Open
Abstract
Aspergillus sydowii is a moderate halophile fungus extensively studied for its biotechnological potential and halophile responses, which has also been reported as a coral reef pathogen. In a recent publication, the transcriptomic analysis of this fungus, when growing on wheat straw, showed that genes related to cell wall modification and cation transporters were upregulated under hypersaline conditions but not under 0.5 M NaCl, the optimal salinity for growth in this strain. This led us to study osmolyte accumulation as a mechanism to withstand moderate salinity. In this work, we show that A. sydowii accumulates trehalose, arabitol, mannitol, and glycerol with different temporal dynamics, which depend on whether the fungus is exposed to hypo- or hyperosmotic stress. The transcripts coding for enzymes responsible for polyalcohol synthesis were regulated in a stress-dependent manner. Interestingly, A. sydowii contains three homologs (Hog1, Hog2 and MpkC) of the Hog1 MAPK, the master regulator of hyperosmotic stress response in S. cerevisiae and other fungi. We show a differential regulation of these MAPKs under different salinity conditions, including sustained basal Hog1/Hog2 phosphorylation levels in the absence of NaCl or in the presence of 2.0 M NaCl, in contrast to what is observed in S. cerevisiae. These findings indicate that halophilic fungi such as A. sydowii utilize different osmoadaptation mechanisms to hypersaline conditions.
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Affiliation(s)
- Eya Caridad Rodríguez-Pupo
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62209, Morelos, Mexico; (E.C.R.-P.); (Y.P.-L.); (M.d.R.R.-H.); (J.L.F.-M.)
- Centro de Investigación en Dinámica Celular, IICBA, UAEM, Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62209, Morelos, Mexico;
| | - Yordanis Pérez-Llano
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62209, Morelos, Mexico; (E.C.R.-P.); (Y.P.-L.); (M.d.R.R.-H.); (J.L.F.-M.)
- Centro de Investigación en Dinámica Celular, IICBA, UAEM, Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62209, Morelos, Mexico;
| | - José Raunel Tinoco-Valencia
- Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Campus Morelos, Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62210, Morelos, Mexico;
| | - Norma Silvia Sánchez
- Instituto de Fisiología Celular, UNAM, Cto. Exterior s/n, Cd. Universitaria, Coyoacán, Ciudad de México C.P. 04510, Federal District, Mexico; (N.S.S.); (F.P.-G.); (M.C.); (A.P.); (O.S.); (J.A.)
| | - Francisco Padilla-Garfias
- Instituto de Fisiología Celular, UNAM, Cto. Exterior s/n, Cd. Universitaria, Coyoacán, Ciudad de México C.P. 04510, Federal District, Mexico; (N.S.S.); (F.P.-G.); (M.C.); (A.P.); (O.S.); (J.A.)
| | - Martha Calahorra
- Instituto de Fisiología Celular, UNAM, Cto. Exterior s/n, Cd. Universitaria, Coyoacán, Ciudad de México C.P. 04510, Federal District, Mexico; (N.S.S.); (F.P.-G.); (M.C.); (A.P.); (O.S.); (J.A.)
| | - Nilda del C. Sánchez
- Centro de Ciencias Genómicas, UNAM, Campus Morelos, Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62210, Morelos, Mexico;
| | - Ayixón Sánchez-Reyes
- Catedras Conacyt-Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Campus Morelos, Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62210, Morelos, Mexico;
| | - María del Rocío Rodríguez-Hernández
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62209, Morelos, Mexico; (E.C.R.-P.); (Y.P.-L.); (M.d.R.R.-H.); (J.L.F.-M.)
| | - Antonio Peña
- Instituto de Fisiología Celular, UNAM, Cto. Exterior s/n, Cd. Universitaria, Coyoacán, Ciudad de México C.P. 04510, Federal District, Mexico; (N.S.S.); (F.P.-G.); (M.C.); (A.P.); (O.S.); (J.A.)
| | - Olivia Sánchez
- Instituto de Fisiología Celular, UNAM, Cto. Exterior s/n, Cd. Universitaria, Coyoacán, Ciudad de México C.P. 04510, Federal District, Mexico; (N.S.S.); (F.P.-G.); (M.C.); (A.P.); (O.S.); (J.A.)
| | - Jesús Aguirre
- Instituto de Fisiología Celular, UNAM, Cto. Exterior s/n, Cd. Universitaria, Coyoacán, Ciudad de México C.P. 04510, Federal District, Mexico; (N.S.S.); (F.P.-G.); (M.C.); (A.P.); (O.S.); (J.A.)
| | - Ramón Alberto Batista-García
- Centro de Investigación en Dinámica Celular, IICBA, UAEM, Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62209, Morelos, Mexico;
| | - Jorge Luis Folch-Mallol
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62209, Morelos, Mexico; (E.C.R.-P.); (Y.P.-L.); (M.d.R.R.-H.); (J.L.F.-M.)
| | - María del Rayo Sánchez-Carbente
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, Cuernavaca C.P. 62209, Morelos, Mexico; (E.C.R.-P.); (Y.P.-L.); (M.d.R.R.-H.); (J.L.F.-M.)
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Bonny AR, Kochanowski K, Diether M, El-Samad H. Stress-induced growth rate reduction restricts metabolic resource utilization to modulate osmo-adaptation time. Cell Rep 2021; 34:108854. [PMID: 33730573 DOI: 10.1016/j.celrep.2021.108854] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/09/2021] [Accepted: 02/18/2021] [Indexed: 01/15/2023] Open
Abstract
A near-constant feature of stress responses is a downregulation or arrest of the cell cycle, resulting in transient growth slowdown. To investigate the role of growth slowdown in the hyperosmotic shock response of S. cerevisiae, we perturbed the G1/S checkpoint protein Sic1 to enable osmo-stress response activation with diminished growth slowdown. We document that in this mutant, adaptation to stress is accelerated rather than delayed. This accelerated recovery of the mutant proceeds by liquidation of internal glycogen stores, which are then shunted into the osmo-shock response. Therefore, osmo-adaptation in wild-type cells is delayed because growth slowdown prevents full accessibility to cellular glycogen stores. However, faster adaptation comes at the cost of acute sensitivity to subsequent osmo-stresses. We suggest that stress-induced growth slowdown acts as an arbiter to regulate the resources devoted to osmo-shock, balancing short-term adaptation with long-term robustness.
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Zimmermannova O, Felcmanova K, Sacka L, Colinet AS, Morsomme P, Sychrova H. K+-specific importers Trk1 and Trk2 play different roles in Ca2+ homeostasis and signalling in Saccharomyces cerevisiae cells. FEMS Yeast Res 2021; 21:6152291. [PMID: 33640956 DOI: 10.1093/femsyr/foab015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/24/2021] [Indexed: 01/06/2023] Open
Abstract
The maintenance of K+ and Ca2+ homeostasis is crucial for many cellular functions. Potassium is accumulated in cells at high concentrations, while the cytosolic level of calcium, to ensure its signalling function, is kept at low levels and transiently increases in response to stresses. We examined Ca2+ homeostasis and Ca2+ signalling in Saccharomyces cerevisiae strains lacking plasma-membrane K+ influx (Trk1 and Trk2) or efflux (Tok1, Nha1 and Ena1-5) systems. The lack of K+ exporters slightly increased the cytosolic Ca2+, but did not alter the Ca2+ tolerance or Ca2+-stress response. In contrast, the K+-importers Trk1 and Trk2 play important and distinct roles in the maintenance of Ca2+ homeostasis. The presence of Trk1 was vital mainly for the growth of cells in the presence of high extracellular Ca2+, whilst the lack of Trk2 doubled steady-state intracellular Ca2+ levels. The absence of both K+ importers highly increased the Ca2+ response to osmotic or CaCl2 stresses and altered the balance between Ca2+ flux from external media and intracellular compartments. In addition, we found Trk2 to be important for the tolerance to high KCl and hygromycin B in cells growing on minimal media. All the data describe new interconnections between potassium and calcium homeostasis in S. cerevisiae.
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Affiliation(s)
- Olga Zimmermannova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 - Krc, 142 20, Czech Republic
| | - Kristina Felcmanova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 - Krc, 142 20, Czech Republic
| | - Lenka Sacka
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 - Krc, 142 20, Czech Republic
| | - Anne-Sophie Colinet
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, B 1348, Louvain-la-Neuve, Belgium
| | - Pierre Morsomme
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, B 1348, Louvain-la-Neuve, Belgium
| | - Hana Sychrova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 - Krc, 142 20, Czech Republic
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10
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Song Y, Zhang Y, He M, Liu H, Hu C, Yang L, Yu P. Enhancing the production of poly-γ-glutamate in Bacillus subtilis ZJS18 by the heat- and osmotic shock and its mechanism. Prep Biochem Biotechnol 2020; 50:1023-1030. [PMID: 32552438 DOI: 10.1080/10826068.2020.1780610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Poly-γ-glutamate (γ-PGA) is a natural macromolecule peptide, and is widely used in the food, medicine, and pharmaceutical industries. In this study, heat- and osmotic shock were used to improve the production of γ-PGA in Bacillus subtilis ZJS18, and its molecular mechanism was explored. The results indicated that the heat- and osmotic shock significantly promoted the production of γ-PGA owing to the stress response of B. subtilis cells to adverse environment. The highest concentrations of γ-PGA reached 14.53 and 15.98 g/l under heat- and osmotic shock, respectively. The activities of five enzymes related to the metabolism of the endogenous glutamate were determined and analyzed. It was found that the activities of glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, glutamate dehydrogenase and glutamate synthase were significantly altered during heat- and osmotic shock, while the activity of α-ketoglutarate dehydrogenase only showed a little alteration. This study provides a basis for the industrial production and use of γ-PGA, and for understanding its biosynthetic mechanism in B. subtilis ZJS18.
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Affiliation(s)
- Yichao Song
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People's Republic of China
| | - Yishu Zhang
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People's Republic of China
| | - Min He
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People's Republic of China
| | - Hang Liu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People's Republic of China
| | - Chunyu Hu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People's Republic of China
| | - Liuzhen Yang
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People's Republic of China
| | - Ping Yu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People's Republic of China
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11
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Schimek C, Egger E, Tauer C, Striedner G, Brocard C, Cserjan-Puschmann M, Hahn R. Extraction of recombinant periplasmic proteins under industrially relevant process conditions: Selectivity and yield strongly depend on protein titer and methodology. Biotechnol Prog 2020; 36:e2999. [PMID: 32259401 PMCID: PMC7685146 DOI: 10.1002/btpr.2999] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/25/2020] [Accepted: 04/01/2020] [Indexed: 02/05/2023]
Abstract
In this work, we attempted to identify a method for the selective extraction of periplasmic endogenously expressed proteins, which is applicable at an industrial scale. For this purpose, we used an expression model that allows coexpression of two fluorescent proteins, each of which is specifically targeted to either the cytoplasm or periplasm. We assessed a number of scalable lysis methods (high‐pressure homogenization, osmotic shock procedures, extraction with ethylenediaminetetraacetic acid, and extraction with deoxycholate) for the ability to selectively extract periplasmic proteins rather than cytoplasmic proteins. Our main conclusion was that although we identified industrially scalable lysis conditions that significantly increased the starting purity for further purification, none of the tested conditions were selective for periplasmic protein over cytoplasmic protein. Furthermore, we demonstrated that efficient extraction of the expressed recombinant proteins was largely dependent on the overall protein concentration in the cell.
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Affiliation(s)
- Clemens Schimek
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Esther Egger
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Christopher Tauer
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Gerald Striedner
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Cécile Brocard
- Biopharma Process Science, Boehringer Ingelheim RCV GmbH & Co KG, Wien, Austria
| | - Monika Cserjan-Puschmann
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Rainer Hahn
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
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12
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Yang D, Männik J, Retterer ST, Männik J. The effects of polydisperse crowders on the compaction of the Escherichia coli nucleoid. Mol Microbiol 2020; 113:1022-1037. [PMID: 31961016 DOI: 10.1111/mmi.14467] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 01/15/2020] [Accepted: 01/15/2020] [Indexed: 01/10/2023]
Abstract
DNA binding proteins, supercoiling, macromolecular crowders, and transient DNA attachments to the cell membrane have all been implicated in the organization of the bacterial chromosome. However, it is unclear what role these factors play in compacting the bacterial DNA into a distinct organelle-like entity, the nucleoid. By analyzing the effects of osmotic shock and mechanical squeezing on Escherichia coli, we show that macromolecular crowders play a dominant role in the compaction of the DNA into the nucleoid. We find that a 30% increase in the crowder concentration from physiological levels leads to a three-fold decrease in the nucleoid's volume. The compaction is anisotropic, being higher along the long axes of the cell at low crowding levels. At higher crowding levels, the nucleoid becomes spherical, and its compressibility decreases significantly. Furthermore, we find that the compressibility of the nucleoid is not significantly affected by cell growth rates and by prior treatment with rifampicin. The latter results point out that in addition to poly ribosomes, soluble cytoplasmic proteins have a significant contribution in determining the size of the nucleoid. The contribution of poly ribosomes dominates at faster and soluble proteins at slower growth rates.
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Affiliation(s)
- Da Yang
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN, USA
| | - Jaana Männik
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN, USA.,Department of Biochemistry, and Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, USA
| | - Scott T Retterer
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Jaan Männik
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN, USA
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13
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Hans F, Glasebach H, Kahle PJ. Multiple distinct pathways lead to hyperubiquitylated insoluble TDP-43 protein independent of its translocation into stress granules. J Biol Chem 2019; 295:673-689. [PMID: 31780563 DOI: 10.1074/jbc.ra119.010617] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 11/15/2019] [Indexed: 12/14/2022] Open
Abstract
Insoluble, hyperubiquitylated TAR DNA-binding protein of 43 kDa (TDP-43) in the central nervous system characterizes frontotemporal dementia and ALS in many individuals with these neurodegenerative diseases. The causes for neuropathological TDP-43 aggregation are unknown, but it has been suggested that stress granule (SG) formation is important in this process. Indeed, in human embryonic kidney HEK293E cells, various SG-forming conditions induced very strong TDP-43 ubiquitylation, insolubility, and reduced splicing activity. Osmotic stress-induced SG formation and TDP-43 ubiquitylation occurred rapidly and coincided with colocalization of TDP-43 and SG markers. Washout experiments confirmed the rapid dissolution of SGs, accompanied by normalization of TDP-43 ubiquitylation and solubility. Surprisingly, interference with the SG process using a protein kinase R-like endoplasmic reticulum kinase inhibitor (GSK2606414) or the translation blocker emetine did not prevent TDP-43 ubiquitylation and insolubility. Thus, parallel pathways may lead to pathological TDP-43 modifications independent of SG formation. Using a panel of kinase inhibitors targeting signaling pathways of the osmotic shock inducer sorbitol, we could largely rule out the stress-activated and extracellular signal-regulated protein kinase modules and glycogen synthase kinase 3β. For arsenite, but not for sorbitol, quenching oxidative stress with N-acetylcysteine did suppress both SG formation and TDP-43 ubiquitylation and insolubility. Thus, sodium arsenite appears to promote SG formation and TDP-43 modifications via oxidative stress, but sorbitol stimulates TDP-43 ubiquitylation and insolubility via a novel pathway(s) independent of SG formation. In conclusion, pathological TDP-43 modifications can be mediated via multiple distinct pathways for which SGs are not essential.
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Affiliation(s)
- Friederike Hans
- German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany
| | - Hanna Glasebach
- Hertie Institute for Clinical Brain Research, Department of Neurodegeneration, University of Tübingen, 72076 Tübingen, Germany
| | - Philipp J Kahle
- German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany .,Hertie Institute for Clinical Brain Research, Department of Neurodegeneration, University of Tübingen, 72076 Tübingen, Germany
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14
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Husain K, Pittayakanchit W, Pattanayak G, Rust MJ, Murugan A. Kalman-like Self-Tuned Sensitivity in Biophysical Sensing. Cell Syst 2019; 9:459-465.e6. [PMID: 31563474 DOI: 10.1016/j.cels.2019.08.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 05/21/2019] [Accepted: 08/20/2019] [Indexed: 02/08/2023]
Abstract
Living organisms need to be sensitive to a changing environment while also ignoring uninformative environmental fluctuations. Here, we argue that living cells can navigate these conflicting demands by dynamically tuning their environmental sensitivity. We analyze the circadian clock in Synechococcus elongatus, showing that clock-metabolism coupling can detect mismatch between clock predictions and the day-night light cycle, temporarily raise the clock's sensitivity to light changes, and thus re-entraining faster. We find analogous behavior in recent experiments on switching between slow and fast osmotic-stress-response pathways in yeast. In both cases, cells can raise their sensitivity to new external information in epochs of frequent challenging stress, much like a Kalman filter with adaptive gain in signal processing. Our work suggests a new class of experiments that probe the history dependence of environmental sensitivity in biophysical sensing mechanisms.
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15
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Amemiya S, Toyoda H, Kimura M, Saito H, Kobayashi H, Ihara K, Kamagata K, Kawabata R, Kato S, Nakashimada Y, Furuta T, Hamamoto S, Uozumi N. The mechanosensitive channel YbdG from Escherichia coli has a role in adaptation to osmotic up-shock. J Biol Chem 2019; 294:12281-12292. [PMID: 31256002 DOI: 10.1074/jbc.ra118.007340] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 06/20/2019] [Indexed: 01/24/2023] Open
Abstract
Mechanosensitive channels play an important role in the adaptation of cells to hypo-osmotic shock. Among members of this channel family in Escherichia coli, the exact function and physiological role of the mechanosensitive channel homolog YbdG remain unclear. Characterization of YbdG's physiological role has been hampered by its lack of measurable transport activity. Using a nitrosoguanidine mutagenesis-aided screen in combination with next-generation sequencing, here we isolated a mutant with a point mutation in ybdG This mutation (resulting in a I167T change) conferred sensitivity to high osmotic stress, and the mutant cells differed from WT cells in morphology during hyperosmotic stress at alkaline pH. Interestingly, unlike the cells containing the I167T variant, a null-ybdG mutant did not exhibit this sensitivity and phenotype. Although I167T was located near the putative ion-conducting pore in a transmembrane region of YbdG, no change in ion channel activities of YbdG-I167T was detected. Of note, introduction of the WT C-terminal cytosolic region of YbdG into the I167T variant complemented the osmo-sensitive phenotype. Co-precipitation of proteins interacting with the C-terminal YbdG region led to the isolation of HldD and FbaA, whose overexpression in cells containing the YbdG-I167T variant partially rescued the osmo-sensitive phenotype. This study indicates that YbdG functions as a component of a mechanosensing system that transmits signals triggered by external osmotic changes to intracellular factors. The cellular role of YbdG uncovered here goes beyond its predicted function as an ion or solute transport protein.
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Affiliation(s)
- Shun Amemiya
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Hayato Toyoda
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Mami Kimura
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Hiromi Saito
- Department of Biochemistry, Graduate School of Pharmaceutical Science, Chiba University, Chiba 260-8675, Japan
| | - Hiroshi Kobayashi
- Department of Biochemistry, Graduate School of Pharmaceutical Science, Chiba University, Chiba 260-8675, Japan
| | - Kunio Ihara
- Center for Gene Research, Nagoya University, Nagoya 464-8602, Japan
| | - Kiyoto Kamagata
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Sendai 980-8577, Japan
| | - Ryuji Kawabata
- School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
| | - Setsu Kato
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Yutaka Nakashimada
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Tadaomi Furuta
- School of Life Science and Technology, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | - Shin Hamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
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16
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Gidske G, Sølvik UØ, Sandberg S, Kristensen GBB. Hemolysis interference studies: freeze method should be used in the preparation of hemolyzed samples. Clin Chem Lab Med 2019; 56:e220-e222. [PMID: 29630512 DOI: 10.1515/cclm-2018-0193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 02/22/2018] [Indexed: 11/15/2022]
Affiliation(s)
- Gro Gidske
- Department of Global Public Health and Primary Care, Faculty of Medicine, University of Bergen, Bergen, Norway
- Norwegian Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, P. O. Box 6165, 5892 Bergen, Norway
| | - Una Ørvim Sølvik
- Department of Global Public Health and Primary Care, Faculty of Medicine, University of Bergen, Bergen, Norway
| | - Sverre Sandberg
- Department of Global Public Health and Primary Care, Faculty of Medicine, University of Bergen, Bergen, Norway
- Norwegian Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway
- Laboratory of Clinical Biochemistry, HaUKeland University Hospital, Bergen, Norway
| | - Gunn Berit Berge Kristensen
- Norwegian Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway
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17
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Al Musaimi O, El-Faham A, Almarhoon Z, Basso A, de la Torre BG, Albericio F. Bypassing Osmotic Shock Dilemma in a Polystyrene Resin Using the Green Solvent Cyclopentyl methyl Ether (CPME): A Morphological Perspective. Polymers (Basel) 2019; 11:polym11050874. [PMID: 31086118 PMCID: PMC6571811 DOI: 10.3390/polym11050874] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 05/02/2019] [Accepted: 05/11/2019] [Indexed: 11/16/2022] Open
Abstract
The “osmotic shock” phenomenon is the main thing that is responsible for morphological structure alteration, which can jeopardize the use of a polymer in a chemical process. This is extremely important in solid-phase peptide synthesis (SPPS), which is the method of choice for the preparation of these important biologically active compounds. Herein, we have used Hildebrand solubility parameters (δ) to investigate the influence of different ethers that are used in the precipitation step of the SPPS using a polystyrene resin. The green cyclopentyl methyl ether (CPME) has shown to be slightly superior to 2-methyltetrahydrofurane, which is also a green ether and clearly better than the hazardous diethyl ether and tert-butyl methyl ether. These results have been corroborated by scanning electron microscope (SEM) analysis and computational studies. All together, these confirm the adequacy of CPME for being the ether of choice to be used in SPPS.
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Affiliation(s)
- Othman Al Musaimi
- Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4001, South Africa.
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa.
| | - Ayman El-Faham
- Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
- Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Alexandria 21321, Egypt.
| | - Zainab Almarhoon
- Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
| | | | - Beatriz G de la Torre
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa.
| | - Fernando Albericio
- Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4001, South Africa.
- Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
- CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Barcelona Science Park, University of Barcelona, 08028 Barcelona, Spain.
- Department of Organic Chemistry, University of Barcelona, 08028 Barcelona, Spain.
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18
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Álvarez-Aragón R, Rodríguez-Navarro A. Nitrate-dependent shoot sodium accumulation and osmotic functions of sodium in Arabidopsis under saline conditions. Plant J 2017; 91:208-219. [PMID: 28370621 DOI: 10.1111/tpj.13556] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 03/24/2017] [Accepted: 03/27/2017] [Indexed: 05/02/2023]
Abstract
Improving crop plants to be productive in saline soils or under irrigation with saline water would be an important technological advance in overcoming the food and freshwater crises that threaten the world population. However, even if the transformation of a glycophyte into a plant that thrives under seawater irrigation was biologically feasible, current knowledge about Na+ effects would be insufficient to support this technical advance. Intriguingly, crucial details about Na+ uptake and its function in the plant have not yet been well established. We here propose that under saline conditions two nitrate-dependent transport systems in series that take up and load Na+ into the xylem constitute the major pathway for the accumulation of Na+ in Arabidopsis shoots; this pathway can also function with chloride at high concentrations. In nrt1.1 nitrate transport mutants, plant Na+ accumulation was partially defective, which suggests that NRT1.1 either partially mediates or modulates the nitrate-dependent Na+ transport. Arabidopsis plants exposed to an osmotic potential of -1.0 MPa (400 mOsm) for 24 h showed high water loss and wilting in sorbitol or Na/MES, where Na+ could not be accumulated. In contrast, in NaCl the plants that accumulated Na+ lost a low amount of water, and only suffered transitory wilting. We discuss that in Arabidopsis plants exposed to high NaCl concentrations, root Na+ uptake and tissue accumulation fulfil the primary function of osmotic adjustment, even if these processes lead to long-term toxicity.
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Affiliation(s)
- Rocío Álvarez-Aragón
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain
| | - Alonso Rodríguez-Navarro
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain
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19
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Ha JH, Eo Y, Ahn HC, Ryu KS. Increasing the soluble expression and crystallization of the Escherichia coli quorum-sensing protein LsrK. Acta Crystallogr F Struct Biol Commun 2017; 73:253-258. [PMID: 28471356 DOI: 10.1107/s2053230x1700468x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 03/26/2017] [Indexed: 11/10/2022]
Abstract
LsrK is one of the key components of the luxS-regulated (lsr) operon in Escherichia coli and plays an important role during the quorum-sensing (QS) process mediated by autoinducer-2 (AI-2). The AI-2 molecule is imported into the cell by the LsrACB transporter and is subsequently phosphorylated (to AI-2-P) by LsrK. AI-2-P binds to the repressor protein of the lsr operon (LsrR) and triggers various cellular responses related to QS by dissociating LsrR from the DNA. Although a large amount of purified LsrK is required for structural studies, recombinant GST-LsrK was mostly expressed in an insoluble form. To enhance the soluble expression of LsrK, an attempt was made to increase the expression of the cellular chaperone proteins that are well known to support proper protein folding. Transformed E. coli was cultured in high-salt LB medium and heat shock was applied prior to subsequent IPTG induction at 20°C. These procedures increased the yield of purified LsrK by about tenfold compared with standard IPTG induction at 20°C. The expressed LsrK was readily purified by GST-affinity chromatography. Crystals of LsrK were grown by the hanging-drop vapour-diffusion method. The X-ray diffraction data of the crystal were processed in a primitive hexagonal space group to 2.9 Å resolution.
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Affiliation(s)
- Jung Hye Ha
- Protein Structure Group, Korea Basic Science Institute, 162 Yeongudanji-ro, Ochang-eup, Cheongju-si, Chungcheongbuk-do 28119, Republic of Korea
| | - Yumi Eo
- Protein Structure Group, Korea Basic Science Institute, 162 Yeongudanji-ro, Ochang-eup, Cheongju-si, Chungcheongbuk-do 28119, Republic of Korea
| | - Hee Chul Ahn
- Department of Pharmacy, College of Pharmacy, Dongguk University Seoul, 32 Dongguk-ro, Ilsandong-gu, Goyang, Gyeonggi-do 10326, Republic of Korea
| | - Kyoung Seok Ryu
- Protein Structure Group, Korea Basic Science Institute, 162 Yeongudanji-ro, Ochang-eup, Cheongju-si, Chungcheongbuk-do 28119, Republic of Korea
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20
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Stadmiller SS, Gorensek-Benitez AH, Guseman AJ, Pielak GJ. Osmotic Shock Induced Protein Destabilization in Living Cells and Its Reversal by Glycine Betaine. J Mol Biol 2017; 429:1155-1161. [PMID: 28263768 PMCID: PMC5985519 DOI: 10.1016/j.jmb.2017.03.001] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 12/18/2022]
Abstract
Many organisms can adapt to changes in the solute content of their surroundings (i.e., the osmolarity). Hyperosmotic shock causes water efflux and a concomitant reduction in cell volume, which is countered by the accumulation of osmolytes. This volume reduction increases the crowded nature of the cytoplasm, which is expected to affect protein stability. In contrast to traditional theory, which predicts that more crowded conditions can only increase protein stability, recent work shows that crowding can destabilize proteins through transient attractive interactions. Here, we quantify protein stability in living Escherichia coli cells before and after hyperosmotic shock in the presence and absence of the osmolyte, glycine betaine. The 7-kDa N-terminal src-homology 3 domain of Drosophila signal transduction protein drk is used as the test protein. We find that hyperosmotic shock decreases SH3 stability in cells, consistent with the idea that transient attractive interactions are important under physiologically relevant crowded conditions. The subsequent uptake of glycine betaine returns SH3 to the stability observed without osmotic shock. These results highlight the effect of transient attractive interactions on protein stability in cells and provide a new explanation for why stressed cells accumulate osmolytes.
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Affiliation(s)
- Samantha S Stadmiller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | | | - Alex J Guseman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Gary J Pielak
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 101 Manning Drive, Chapel Hill, NC 27514, USA.
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21
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Abstract
Current advances in selective enrichment, fractionation, and MS detection of phosphorylated peptides allowed identification and quantitation of tens of thousands phosphosites from minute amounts of biological material. One of the major challenges in the field is preserving the in vivo phosphorylation state of the proteins throughout the sample preparation workflow. This is typically achieved by using phosphatase inhibitors and denaturing conditions during cell lysis. Here we determine if the upstream cell collection techniques could introduce changes in protein phosphorylation. To evaluate the effect of sample collection protocols on the global phosphorylation status of the cell, we compared different sample workflows by metabolic labeling and quantitative mass spectrometry on Saccharomyces cerevisiae cell cultures. We identified highly similar phosphopeptides for cells harvested in ice cold isotonic phosphate buffer, cold ethanol, trichloroacetic acid, and liquid nitrogen. However, quantitative analyses revealed that the commonly used phosphate buffer unexpectedly activated signaling events. Such effects may introduce systematic bias in phosphoproteomics measurements and biochemical analysis.
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Affiliation(s)
- Evgeny Kanshin
- †Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Michael Tyers
- †Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec H3C 3J7, Canada.,‡Department of Medicine, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Pierre Thibault
- †Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec H3C 3J7, Canada.,§Department of Chemistry, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec H3C 3J7, Canada
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22
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Martin H, Shales M, Fernandez-Piñar P, Wei P, Molina M, Fiedler D, Shokat KM, Beltrao P, Lim W, Krogan NJ. Differential genetic interactions of yeast stress response MAPK pathways. Mol Syst Biol 2015; 11:800. [PMID: 25888283 PMCID: PMC4422557 DOI: 10.15252/msb.20145606] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Genetic interaction screens have been applied with great success in several organisms to study gene function and the genetic architecture of the cell. However, most studies have been performed under optimal growth conditions even though many functional interactions are known to occur under specific cellular conditions. In this study, we have performed a large-scale genetic interaction analysis in Saccharomyces cerevisiae involving approximately 49 × 1,200 double mutants in the presence of five different stress conditions, including osmotic, oxidative and cell wall-altering stresses. This resulted in the generation of a differential E-MAP (or dE-MAP) comprising over 250,000 measurements of conditional interactions. We found an extensive number of conditional genetic interactions that recapitulate known stress-specific functional associations. Furthermore, we have also uncovered previously unrecognized roles involving the phosphatase regulator Bud14, the histone methylation complex COMPASS and membrane trafficking complexes in modulating the cell wall integrity pathway. Finally, the osmotic stress differential genetic interactions showed enrichment for genes coding for proteins with conditional changes in phosphorylation but not for genes with conditional changes in gene expression. This suggests that conditional genetic interactions are a powerful tool to dissect the functional importance of the different response mechanisms of the cell.
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Affiliation(s)
- Humberto Martin
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid and Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), Madrid, Spain
| | - Michael Shales
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA USA
| | - Pablo Fernandez-Piñar
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid and Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), Madrid, Spain
| | - Ping Wei
- Center for Quantitative Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Maria Molina
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid and Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), Madrid, Spain
| | - Dorothea Fiedler
- Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Kevan M Shokat
- Chemistry and Chemical Biology Graduate Program, University of California, San Francisco, CA, USA
| | - Pedro Beltrao
- European Molecular Biology Laboratory, European Bioinformatics Institute, Cambridge, UK iBiMED and Department of Health Sciences, University of Aveiro, Aveiro, Portugal
| | - Wendell Lim
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA USA Howard Hughes Medical Institute, University of California, San Francisco, CA, USA Center for Systems and Synthetic Biology, University of California, San Francisco, CA, USA
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA USA Center for Systems and Synthetic Biology, University of California, San Francisco, CA, USA California Institute for Quantitative Biosciences, QB3, San Francisco, CA, USA J. David Gladstone Institutes, San Francisco, CA, USA
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23
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Nakayama Y, Hirata A, Iida H. Mechanosensitive channels Msy1 and Msy2 are required for maintaining organelle integrity upon hypo osmotic shock in Schizosaccharomyces pombe. FEMS Yeast Res 2014; 14:992-4. [PMID: 25041276 DOI: 10.1111/1567-1364.12181] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 06/30/2014] [Accepted: 07/03/2014] [Indexed: 11/29/2022] Open
Abstract
The mechanosensitive channels, Mys1 and Msy2, in fission yeast are localized in the endoplasmic reticulum membrane and control cytoplasmic Ca(2+) levels in the hypoosmotic response. We here investigated changes in organellar structures with hypoosmotic shock using transmission electron microscopy. While msy1(-) and msy2(-) single mutant cells developed a number of swollen vacuoles following hypoosmotic shock, similar to wild-type cells, msy1(-) msy2(-) double mutant cells only had two abnormally large vacuoles and cracks between the inner and outer nuclear membranes. These results suggest that Msy1 and Msy2 may be involved in maintaining vacuole integrity and protecting the nuclear envelope upon hypoosmotic shock and also that these two channels are functionally complementary.
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Affiliation(s)
- Yoshitaka Nakayama
- Department of Biology, Tokyo Gakugei University, Koganei-shi, Tokyo, Japan
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24
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Lee J, Reiter W, Dohnal I, Gregori C, Beese-Sims S, Kuchler K, Ammerer G, Levin DE. MAPK Hog1 closes the S. cerevisiae glycerol channel Fps1 by phosphorylating and displacing its positive regulators. Genes Dev 2014; 27:2590-601. [PMID: 24298058 PMCID: PMC3861672 DOI: 10.1101/gad.229310.113] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The yeast aquagylceroporin Fps1 is a key regulator of glycerol transport in response to changes in extracellular osmolarity. Here, Lee et al. delineate how the MAPK Hog1 and glycerol channel regulators Rgc1/2 control Fps1 channel activity. The authors show that Rgc2 maintains Fps1 in an open channel state via split pleckstrin homology domains within both proteins. Hog1 induces Fbs1 channel closure by binding Fps1 and phosphorylating the activating subunit Rgc2. This study reveals a new aspect of spatial control mechanisms used by MAPKs to regulate their targets. The aquaglyceroprin Fps1 is responsible for glycerol transport in yeast in response to changes in extracellular osmolarity. Control of Fps1 channel activity in response to hyperosmotic shock involves a redundant pair of regulators, Rgc1 (regulator of the glycerol channel 1) and Rgc2, and the MAPK Hog1 (high-osmolarity glycerol response 1). However, the mechanism by which these factors influence channel activity is unknown. We show that Rgc2 maintains Fps1 in the open channel state in the absence of osmotic stress by binding to its C-terminal cytoplasmic domain. This interaction involves a tripartite pleckstrin homology (PH) domain within Rgc2 and a partial PH domain within Fps1. Activation of Hog1 in response to hyperosmotic shock induces the rapid eviction of Rgc2 from Fps1 and consequent channel closure. Hog1 was recruited to the N-terminal cytoplasmic domain of Fps1, which it uses as a platform from which to multiply phosphorylate Rgc2. Thus, these results reveal the mechanism by which Hog1 regulates Fps1 in response to hyperosmotic shock.
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Affiliation(s)
- Jongmin Lee
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts 02118, USA
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25
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Cook KE, O'Shea EK. Hog1 controls global reallocation of RNA Pol II upon osmotic shock in Saccharomyces cerevisiae. G3 (Bethesda) 2012; 2:1129-36. [PMID: 22973550 DOI: 10.1534/g3.112.003251] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 07/14/2012] [Indexed: 12/12/2022]
Abstract
When challenged with osmotic shock, Saccharomyces cerevisiae induces hundreds of genes, despite a concurrent reduction in overall transcriptional capacity. The stress-responsive MAP kinase Hog1 activates expression of specific genes through interactions with chromatin remodeling enzymes, transcription factors, and RNA polymerase II. However, it is not clear whether Hog1 is involved more globally in modulating the cell’s transcriptional program during stress, in addition to activating specific genes. Here we show that large-scale redistribution of RNA Pol II from housekeeping to stress genes requires Hog1. We demonstrate that decreased RNA Pol II occupancy is the default outcome for highly expressed genes upon stress and that Hog1 is partially required for this effect. We find that Hog1 and RNA Pol II colocalize to open reading frames that bypass global transcriptional repression. These activation targets are specified by promoter binding of two osmotic stress-responsive transcription factors. The combination of reduced global transcription with a gene-specific override mechanism allows cells to rapidly switch their transcriptional program in response to stress.
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26
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Azevedo NF, Bragança SM, Simões LC, Cerqueira L, Almeida C, Keevil CW, Vieira MJ. Proposal for a method to estimate nutrient shock effects in bacteria. BMC Res Notes 2012; 5:422. [PMID: 22873690 PMCID: PMC3490807 DOI: 10.1186/1756-0500-5-422] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 07/12/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plating methods are still the golden standard in microbiology; however, some studies have shown that these techniques can underestimate the microbial concentrations and diversity. A nutrient shock is one of the mechanisms proposed to explain this phenomenon. In this study, a tentative method to assess nutrient shock effects was tested. FINDINGS To estimate the extent of nutrient shock effects, two strains isolated from tap water (Sphingomonas capsulata and Methylobacterium sp.) and two culture collection strains (E. coli CECT 434 and Pseudomonas fluorescens ATCC 13525) were exposed both to low and high nutrient conditions for different times and then placed in low nutrient medium (R2A) and rich nutrient medium (TSA).The average improvement (A.I.) of recovery between R2A and TSA for the different times was calculated to more simply assess the difference obtained in culturability between each medium. As expected, A.I. was higher when cells were plated after the exposition to water than when they were recovered from high-nutrient medium showing the existence of a nutrient shock for the diverse bacteria used. S. capsulata was the species most affected by this phenomenon. CONCLUSIONS This work provides a method to consistently determine the extent of nutrient shock effects on different microorganisms and hence quantify the ability of each species to deal with sudden increases in substrate concentration.
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Affiliation(s)
- Nuno F Azevedo
- LEPAE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Roberto Frias, 4200-465, Porto, Portugal
- IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057, Braga, Portugal
| | - Sofia M Bragança
- IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057, Braga, Portugal
| | - Lúcia C Simões
- IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057, Braga, Portugal
| | - Laura Cerqueira
- IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057, Braga, Portugal
| | - Carina Almeida
- LEPAE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Roberto Frias, 4200-465, Porto, Portugal
- IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057, Braga, Portugal
| | - Charles W Keevil
- Environmental Healthcare Unit, Microbiology Group, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton, SO16 7PX, United Kingdom
| | - Maria J Vieira
- IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057, Braga, Portugal
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Abstract
BACKGROUND AND AIMS Water adhesion forces, water absorption capacity and permeability of the pine exine were investigated to consider a possible function of sporopollenin coatings in the control of water transport. METHODS The experiments were carried out with sporopollenin capsules obtained from pine pollen consisting of an empty central capsule and two sacci. Changes in the concentration of excluded dextran molecules in the medium were analysed to quantify water absorption by purified exine fragments and the osmotic volume flow out of the intact central capsule. KEY RESULTS The contact angle of sporopollenin to water is higher than the one to ethanol and lower than the one to n-heptane. The water-filled pore space in pine sporopollenin amounts to only 20.6 % of the matrix volume. A monosaccharide was excluded from 15 % and a trisaccharide from about 38 % of this space. Shrinkage of the central capsule induced by permeable osmotica was transient, whereas that induced by sodium polyacrylate (2100 g mol(-1)) was stable. Values obtained for the hydraulic conductance L(P) of the exine (0.39-0.48 microm s(-1) MPa(-1)) are comparable in size to those of biomembranes. Sodium sulfate solutions induced a significant osmotic flow through the exine (reflection coefficient at least 0.6). The exine around the central capsule can be ruptured by equilibration of its lumen with a concentrated electrolyte solution and subsequent transfer to water. The denatured protoplast along with the intact intine was ejected when pollen grains were subjected to this osmotic shock treatment. CONCLUSIONS The pine exine is easily wetted with water and does not represent a significant barrier to water exchange either liquid or gaseous. Through osmotic burst, it can be separated from the intine. The effect of salts and small solute molecules on water fluxes may be functionally significant for rehydration upon pollination.
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Affiliation(s)
- GUIDO BOHNE
- Institute of Biology, Humboldt-University Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | | | - RUDOLF EHWALD
- Institute of Biology, Humboldt-University Berlin, Invalidenstr. 42, 10115 Berlin, Germany
- For correspondence. E-mail
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