Thiol switches in membrane proteins - Extracellular redox regulation in cell biology

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Inken Lorenzen ◽  
Johannes A. Eble ◽  
Eva-Maria Hanschmann
Keyword(s):  
Membrane Proteins ◽  
Conformational Changes ◽  
Cell Biology ◽  
Redox Regulation ◽  
Cell Metabolism ◽  
Second Messengers ◽  
Enzymatic Production ◽  
Underlying Mechanisms ◽  
Specific Reactions ◽  
Disulfide Isomerization

AbstractRedox-mediated signal transduction depends on the enzymatic production of second messengers such as hydrogen peroxide, nitric oxide and hydrogen sulfite, as well as specific, reversible redox modifications of cysteine-residues in proteins. So-called thiol switches induce for instance conformational changes in specific proteins that regulate cellular pathways e.g., cell metabolism, proliferation, migration, gene expression and inflammation. Reduction, oxidation and disulfide isomerization are controlled by oxidoreductases of the thioredoxin family, including thioredoxins, glutaredoxins, peroxiredoxins and protein dsisulfide isomerases. These proteins are located in different cellular compartments, interact with substrates and catalyze specific reactions. Interestingly, some of these proteins are released by cells. Their extracellular functions and generally extracellular redox control have been widely underestimated. Here, we give an insight into extracellular redox signaling, extracellular thiol switches and their regulation by secreted oxidoreductases and thiol-isomerases, a topic whose importance has been scarcely studied so far, likely due to methodological limitations. We focus on the secreted redox proteins and characterized thiol switches in the ectodomains of membrane proteins, such as integrins and the metalloprotease ADAM17, which are among the best-characterized proteins and discuss their underlying mechanisms and biological implications.

scholarly journals Intercellular calcium signalling between chondrocytes and synovial cells in co-culture

1998 ◽  
Vol 329 (3) ◽  
pp. 681-687 ◽  
Author(s):  
Paola D'ANDREA ◽  
Alessandra CALABRESE ◽  
Micaela GRANDOLFO
Keyword(s):  
Gap Junctions ◽  
Intercellular Communication ◽  
Structural Changes ◽  
Articular Chondrocytes ◽  
Cell Metabolism ◽  
Second Messengers ◽  
Calcium Signalling ◽  
Cell Types ◽  
Synovial Cells ◽  
Cell Coupling

Intercellular communication allows the co-ordination of cell metabolism between tissues as well as sensitivity to extracellular stimuli. Paracrine stimulation and cell-to-cell coupling through gap junctions induce the formation of complex cellular networks that favour the intercellular exchange of nutrients and second messengers. Heterologous intercellular communication was studied in co-cultures of articular chondrocytes and HIG-82 synovial cells by measuring mechanically induced cytosolic changes in Ca2+ ion levels by digital fluorescence video imaging. In confluent co-cultures, mechanical stimulation induced intercellular Ca2+ waves that propagated to both cell types with similar kinetics. Intercellular wave spreading was inhibited by 18α-glycyrrhetinic acid and by treatments inhibiting the activation of purinoreceptors, suggesting that intercellular signalling between these two cell types occurs both through gap junctions and ATP-mediated paracrine stimulation. In rheumatoid arthritis the formation of the synovial pannus induces structural changes at the chondrosynovial junction, where chondrocyte and synovial cells come into close apposition: these results provide the first evidence for direct intercellular communication between these two cell types.

scholarly journals Periprotein lipidomes of Saccharomyces cerevisiae provide a flexible environment for conformational changes of membrane proteins

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Joury S van 't Klooster ◽  
Tan-Yun Cheng ◽  
Hendrik R Sikkema ◽  
Aike Jeucken ◽  
Branch Moody ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Small Molecules ◽  
Conformational Changes ◽  
Direct Detection ◽  
Protein Complexes ◽  
Lateral Diffusion ◽  
Low Ph ◽  
Lipid Particles ◽  
High Degree

Yeast tolerates a low pH and high solvent concentrations. The permeability of the plasma membrane (PM) for small molecules is low and lateral diffusion of proteins is slow. These findings suggest a high degree of lipid order, which raises the question of how membrane proteins function in such an environment. The yeast PM is segregated into the Micro-Compartment-of-Can1 (MCC) and Pma1 (MCP), which have different lipid compositions. We extracted proteins from these microdomains via stoichiometric capture of lipids and proteins in styrene-maleic-acid-lipid-particles (SMALPs). We purified SMALP-lipid-protein complexes by chromatography and quantitatively analyzed periprotein lipids located within the diameter defined by one SMALP. Phospholipid and sterol concentrations are similar for MCC and MCP, but sphingolipids are enriched in MCP. Ergosterol is depleted from this periprotein lipidome, whereas phosphatidylserine is enriched relative to the bulk of the plasma membrane. Direct detection of PM lipids in the 'periprotein space' supports the conclusion that proteins function in the presence of a locally disordered lipid state.

scholarly journals Quantification of microenvironmental metabolites in murine cancer models reveals determinants of tumor nutrient availability

2018 ◽  
Author(s):  
Mark R. Sullivan ◽  
Laura V. Danai ◽  
Caroline A. Lewis ◽  
Sze Ham Chan ◽  
Dan Y. Gui ◽  
...  
Keyword(s):  
Cancer Cell ◽  
Nutrient Availability ◽  
Cell Biology ◽  
Interstitial Fluid ◽  
Cell Metabolism ◽  
Extracellular Fluid ◽  
Anatomical Location ◽  
Tumor Type ◽  
Nutrient Levels ◽  
Tumor Interstitial Fluid

AbstractCancer cell metabolism is heavily influenced by microenvironmental factors, including nutrient availability. Therefore, knowledge of microenvironmental nutrient levels is essential to understand tumor metabolism. To measure the extracellular nutrient levels available to tumors, we developed a quantitative metabolomics method to measure the absolute concentrations of >118 metabolites in plasma and tumor interstitial fluid, the extracellular fluid that perfuses tumors. Comparison of nutrient levels in tumor interstitial fluid and plasma revealed that the nutrients available to tumors differ from those present in circulation. Further, by comparing interstitial fluid nutrient levels between autochthonous and transplant models of murine pancreatic and lung adenocarcinoma, we found that tumor type, anatomical location and animal diet affect local nutrient availability. These data provide a comprehensive characterization of the nutrients present in the tumor microenvironment of widely used models of lung and pancreatic cancer and identify factors that influence metabolite levels in tumors.Impact StatementNutrient availability is an important tumor microenvironmental factor that impacts cancer cell biology; we developed methods to measure nutrients available to tumor cells and characterized factors that influence tumor nutrient availability.

scholarly journals Cryo-EM structure of phosphodiesterase 6 reveals insights into the allosteric regulation of type I phosphodiesterases

2019 ◽  
Vol 5 (2) ◽  
pp. eaav4322 ◽  
Author(s):  
Sahil Gulati ◽  
Krzysztof Palczewski ◽  
Andreas Engel ◽  
Henning Stahlberg ◽  
Lubomir Kovacik
Keyword(s):  
Conformational Changes ◽  
Second Messengers ◽  
Structural Features ◽  
Full Length ◽  
Type I ◽  
Regulatory Domains ◽  
Catalytic Domains ◽  
Cryo Electron Microscopy ◽  
Density Map ◽  
G Protein Coupled

Cyclic nucleotide phosphodiesterases (PDEs) work in conjunction with adenylate/guanylate cyclases to regulate the key second messengers of G protein–coupled receptor signaling. Previous attempts to determine the full-length structure of PDE family members at high-resolution have been hindered by structural flexibility, especially in their linker regions and N- and C-terminal ends. Therefore, most structure-activity relationship studies have so far focused on truncated and conserved catalytic domains rather than the regulatory domains that allosterically govern the activity of most PDEs. Here, we used single-particle cryo–electron microscopy to determine the structure of the full-length PDE6αβ2γ complex. The final density map resolved at 3.4 Å reveals several previously unseen structural features, including a coiled N-terminal domain and the interface of PDE6γ subunits with the PDE6αβ heterodimer. Comparison of the PDE6αβ2γ complex with the closed state of PDE2A sheds light on the conformational changes associated with the allosteric activation of type I PDEs.

Invited Review: Engineering approaches to cytoskeletal mechanics

2000 ◽  
Vol 89 (5) ◽  
pp. 2085-2090 ◽  
Author(s):  
Dimitrije Stamenović ◽  
Ning Wang
Keyword(s):  
Cell Biology ◽  
Theoretical Models ◽  
Force Balance ◽  
Mechanical Forces ◽  
Cellular Functions ◽  
Cellular Mechanics ◽  
Recent Developments ◽  
Biochemical Mechanisms ◽  
Underlying Mechanisms ◽  
Biochemical Signals

An outstanding problem in cell biology is how cells sense mechanical forces and how those forces affect cellular functions. Various biophysical and biochemical mechanisms have been invoked to answer this question. A growing body of evidence indicates that the deformable cytoskeleton (CSK), an intracellular network of interconnected filamentous biopolymers, provides a physical basis for transducing mechanical signals into biochemical signals. Therefore, to understand how mechanical forces regulate cellular functions, it is important to know how cells respond to changes in the CSK force balance and to identify the underlying mechanisms that control transmission of mechanical forces throughout the CSK and bring it to equilibrium. Recent developments of new experimental techniques for measuring cell mechanical properties and novel theoretical models of cellular mechanics make it now possible to identify and quantitate the contributions of various CSK structures to the overall balance of mechanical forces in the cell. This review focuses on engineering approaches that have been used in the past two decades in studies of the mechanics of the CSK.

SEARCHING AND MINING VISUALLY OBSERVED PHENOTYPES OF MAIZE MUTANTS

2007 ◽  
Vol 05 (06) ◽  
pp. 1193-1213 ◽  
Author(s):  
CHI-REN SHYU ◽  
JATURON HARNSOMBURANA ◽  
JASON GREEN ◽  
ADRIAN S. BARB ◽  
TONI KAZIC ◽  
...  
Keyword(s):  
Cell Biology ◽  
Species Conservation ◽  
Genetic Maps ◽  
Cell Physiology ◽  
Complex Processes ◽  
Intimate Knowledge ◽  
Scientific Challenge ◽  
Underlying Mechanisms ◽  
Mutant Phenotypes ◽  
High Level

There are thousands of maize mutants, which are invaluable resources for plant research. Geneticists use them to study underlying mechanisms of biochemistry, cell biology, cell development, and cell physiology. To streamline the understanding of such complex processes, researchers need the most current versions of genetic and physical maps, tools with the ability to recognize novel phenotypes or classify known phenotypes, and an intimate knowledge of the biochemical processes generating physiological and phenotypic effects. They must also know how all of these factors change and differ among species, diverse alleles, germplasms, and environmental conditions. While there are robust databases, such as MaizeGDB, for some of these types of raw data, other crucial components are missing. Moreover, the management of visually observed mutant phenotypes is still in its infant stage, let alone the complex query methods that can draw upon high-level and aggregated information to answer the questions of geneticists. In this paper, we address the scientific challenge and propose to develop a robust framework for managing the knowledge of visually observed phenotypes, mining the correlation of visual characteristics with genetic maps, and discovering the knowledge relating to cross-species conservation of visual and genetic patterns. The ultimate goal of this research is to allow a geneticist to submit phenotypic and genomic information on a mutant to a knowledge base and ask, "What genes or environmental factors cause this visually observed phenotype?".

scholarly journals Role of the cysteine residues in Arabidopsis thaliana cyclophilin CYP20-3 in peptidyl-prolyl cis–trans isomerase and redox-related functions

2006 ◽  
Vol 401 (1) ◽  
pp. 287-297 ◽  
Author(s):  
Miriam Laxa ◽  
Janine König ◽  
Karl-Josef Dietz ◽  
Andrea Kandlbinder
Keyword(s):  
Conformational Changes ◽  
Protein Function ◽  
Redox Regulation ◽  
Catalytic Efficiency ◽  
Structural Rearrangement ◽  
Disulfide Bridge ◽  
Cysteine Residues ◽  
Active Centre ◽  
Independent Functions

Cyps (cyclophilins) are ubiquitous proteins of the immunophilin superfamily with proposed functions in protein folding, protein degradation, stress response and signal transduction. Conserved cysteine residues further suggest a role in redox regulation. In order to get insight into the conformational change mechanism and functional properties of the chloroplast-located CYP20-3, site-directed mutagenized cysteine→serine variants were generated and analysed for enzymatic and conformational properties under reducing and oxidizing conditions. Compared with the wild-type form, elimination of three out of the four cysteine residues decreased the catalytic efficiency of PPI (peptidyl-prolyl cis–trans isomerase) activity of the reduced CYP20-3, indicating a regulatory role of dithiol–disulfide transitions in protein function. Oxidation was accompanied by conformational changes with a predominant role in the structural rearrangement of the disulfide bridge formed between Cys54 and Cys171. The rather negative Em (midpoint redox potential) of −319 mV places CYP20-3 into the redox hierarchy of the chloroplast, suggesting the activation of CYP20-3 in the light under conditions of limited acceptor availability for photosynthesis as realized under environmental stress. Chloroplast Prx (peroxiredoxins) were identified as interacting partners of CYP20-3 in a DNA-protection assay. A catalytic role in the reduction of 2-Cys PrxA and 2-Cys PrxB was assigned to Cys129 and Cys171. In addition, it was shown that the isomerization and disulfide-reduction activities are two independent functions of CYP20-3 that both are regulated by the redox state of its active centre.

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