scholarly journals Plant plasma membrane water channels conduct the signalling molecule H2O2

2008 ◽  
Vol 414 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Marek Dynowski ◽  
Gabriel Schaaf ◽  
Dominique Loque ◽  
Oscar Moran ◽  
Uwe Ludewig
Keyword(s):  
Crystal Structure ◽  
Plasma Membrane ◽  
Lipid Bilayers ◽  
Plasma Membranes ◽  
Oxygen Species ◽  
Plasma Membrane Intrinsic Protein ◽  
Signalling Molecule ◽  
Response To Stress ◽  
Dynamics Simulations ◽  
Plant Plasma Membrane

H2O2 is a relatively long-lived reactive oxygen species that signals between cells and organisms. H2O2 signalling in plants is essential for response to stress, defence against pathogens and the regulation of programmed cell death. Although H2O2 diffusion across membranes is often considered as a passive property of lipid bilayers, native membranes represent significant barriers for H2O2. In the present study we addressed the question of whether channels might facilitate H2O2 conduction across plasma membranes. The expression of several plant plasma membrane aquaporins in yeast, including PIP2;1 from Arabidopsis (where PIP is plasma membrane intrinsic protein), enhanced the toxicity of H2O2 and increased the fluorescence of dye-loaded yeast when exposed to H2O2. The sensitivity of aquaporin-expressing yeast to H2O2 was altered by mutations that alter gating and the selectivity of the aquaporins. The conduction of water, H2O2 and urea was compared, using molecular dynamics simulations based on the crystal structure of SoPIP2;1 from spinach. The calculations identify differences in the conduction between the substrates and reveal channel residues critically involved in H2O2 conduction. The results of the calculations on tetramers and monomers are in agreement with the biochemical data. Taken together, the results strongly suggest that plasma membrane aquaporin pores determine the efficiency of H2O2 signalling between cells. Aquaporins are present in most species and their capacity to facilitate the diffusion of H2O2 may be of physiological significance in many organisms and particularly in communication between different species.

scholarly journals Exploring the Dual Interaction of Natural Rhamnolipids with Plant and Fungal Biomimetic Plasma Membranes through Biophysical Studies

2019 ◽  
Vol 20 (5) ◽  
pp. 1009 ◽  
Author(s):  
Noadya Monnier ◽  
Aurélien Furlan ◽  
Sébastien Buchoux ◽  
Magali Deleu ◽  
Manuel Dauchez ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Bilayers ◽  
Plasma Membranes ◽  
Plant Protection ◽  
Md Simulations ◽  
Lipid Dynamics ◽  
Defense Induction ◽  
Membrane Models ◽  
Plant Plasma Membrane ◽  
Membrane Destabilization

Rhamnolipids (RLs) are potential biocontrol agents for crop culture protection. Their mode of action has been proposed as dual, combining plant protection activation and antifungal activities. The present work focuses on the interaction of natural RLs with plant and fungi membrane models at the molecular scale. Representative models were constructed and the interaction with RLs was studied by Fourier transform infrared (FTIR) and deuterium nuclear magnetic resonance (2H NMR) spectroscopic measurements. Molecular dynamic (MD) simulations were performed to investigate RL insertion in lipid bilayers. Our results showed that the RLs fit into the membrane models and were located near the lipid phosphate group of the phospholipid bilayers, nearby phospholipid glycerol backbones. The results obtained with plant plasma membrane models suggest that the insertion of RLs inside the lipid bilayer did not significantly affect lipid dynamics. Oppositely, a clear fluidity increase of fungi membrane models was observed. This effect was related to the presence and the specific structure of ergosterol. The nature of the phytosterols could also influence the RL effect on plant plasma membrane destabilization. Subtle changes in lipid dynamics could then be linked with plant defense induction and the more drastic effects associated with fungal membrane destabilization.

scholarly journals Fusion of lysosomes to plasma membrane initiates radiation-induced apoptosis

2020 ◽  
Vol 219 (4) ◽  
Author(s):  
Charles S. Ferranti ◽  
Jin Cheng ◽  
Chris Thompson ◽  
Jianjun Zhang ◽  
Jimmy A. Rotolo ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Ionizing Radiation ◽  
Plasma Membranes ◽  
Calcium Influx ◽  
Acid Sphingomyelinase ◽  
Oxygen Species ◽  
Physical Damage ◽  
Biophysical Mechanism ◽  
Radiation Induced ◽  
Induced Apoptosis

Diverse stresses, including reactive oxygen species (ROS), ionizing radiation, and chemotherapies, activate acid sphingomyelinase (ASMase) and generate the second messenger ceramide at plasma membranes, triggering apoptosis in specific cells, such as hematopoietic cells and endothelium. Ceramide elevation drives local bilayer reorganization into ceramide-rich platforms, macrodomains (0.5–5-µm diameter) that transmit apoptotic signals. An unresolved issue is how ASMase residing within lysosomes is released extracellularly within seconds to hydrolyze sphingomyelin preferentially enriched in outer plasma membranes. Here we show that physical damage by ionizing radiation and ROS induces full-thickness membrane disruption that allows local calcium influx, membrane lysosome fusion, and ASMase release. Further, electron microscopy reveals that plasma membrane “nanopore-like” structures (∼100-nm diameter) form rapidly due to lipid peroxidation, allowing calcium entry to initiate lysosome fusion. We posit that the extent of upstream damage to mammalian plasma membranes, calibrated by severity of nanopore-mediated local calcium influx for lysosome fusion, represents a biophysical mechanism for cell death induction.

scholarly journals Molecular determinants of the modulation of the VSD-PD coupling mechanism of the KV7.1 channel by the KCNE1 ancillary subunits

2021 ◽  
Author(s):  
Audrey DEYAWE KONGMENECK ◽  
Marina Kasimova ◽  
MOUNIR TAREK
Keyword(s):  
Lipid Bilayers ◽  
Plasma Membranes ◽  
Phosphatidyl Inositol ◽  
Conformational Space ◽  
Coupling Mechanism ◽  
Cardiac Action ◽  
Molecular Determinants ◽  
Dynamics Simulations ◽  
Pore Domain ◽  
Α Subunits

The IKS current is diffused through the plasma membranes of cardiomyocytes during the last phase of the cardiac action potential. This repolarization current is conducted by a tetrameric protein complex derived from the co-expression of four voltage-gated potassium channel KV7.1 α-subunits and KCNE1 ancillary subunits from KCNQ1 and KCNE1 genes, respectively. We studied here the conformational space of KV7.1 in presence and absence of KCNE1, by building transmembrane models of their known Resting, Intermediate, and Activated states. We conducted Molecular Dynamics simulations of these models in lipid bilayers including the phosphatidyl-inositol-4,5-bisphosphate (PIP2) lipids. The comparative analysis of MD trajectories obtained for the KV7.1 and IKS models reveals how KCNE1 shifts the coupling mechanism between the activation state of the Voltage Sensor Domain of the channel and the conformation (open or closed) of its Pore Domain.

Imaging plasma membrane phase behaviour in live cells using a thiophene-based molecular rotor

2016 ◽  
Vol 52 (90) ◽  
pp. 13269-13272 ◽  
Author(s):  
Michael R. Dent ◽  
Ismael López-Duarte ◽  
Callum J. Dickson ◽  
Phoom Chairatana ◽  
Harry L. Anderson ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Bilayers ◽  
Plasma Membranes ◽  
Live Cell ◽  
Phase Behaviour ◽  
Live Cells ◽  
Molecular Rotor ◽  
Membrane Phase ◽  
Artificial Lipid Bilayers ◽  
Cell Plasma

A thiophene-based molecular rotor was used to probe ordering and viscosity within artificial lipid bilayers and live cell plasma membranes.

Signal transfer in the plant plasma membrane: phospholipase A2 is regulated via an inhibitory Gα protein and a cyclophilin

2013 ◽  
Vol 450 (3) ◽  
pp. 497-509 ◽  
Author(s):  
Michael Heinze ◽  
Madeleine Herre ◽  
Carolin Massalski ◽  
Isabella Hermann ◽  
Udo Conrad ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Phospholipase A2 ◽  
Plasma Membranes ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
California Poppy ◽  
Activity State ◽  
Split Ubiquitin ◽  
Low Activity ◽  
Plant Plasma Membrane

The plasma membrane of the California poppy is known to harbour a PLA2 (phospholipase A2) that is associated with the Gα protein which facilitates its activation by a yeast glycoprotein, thereby eliciting the biosynthesis of phytoalexins. To understand the functional architecture of the protein complex, we titrated purified plasma membranes with the Gα protein (native or recombinant) and found that critical amounts of this subunit keep PLA2 in a low-activity state from which it is released either by elicitor plus GTP or by raising the Gα concentration, which probably causes oligomerization of Gα, as supported by FRET (fluorescence resonance energy transfer)-orientated fluorescence imaging and a semiquantitative split-ubiquitin assay. All effects of Gα were blocked by specific antibodies. A low-Gα mutant showed elevated PLA2 activity and lacked the GTP-dependent stimulation by elicitor, but regained this capability after pre-incubation with Gα. The inhibition by Gα and the GTP-dependent stimulation of PLA2 were diminished by inhibitors of peptidylprolyl cis–trans isomerases. A cyclophilin was identified by sequence in the plasma membrane and in immunoprecipitates with anti-Gα antibodies. We conclude that soluble and target-associated Gα interact at the plasma membrane to build complexes of varying architecture and signal amplification. Protein-folding activity is probably required to convey conformational transitions from Gα to its target PLA2.

Mercury increases water permeability of a plant aquaporin through a non-cysteine-related mechanism

2013 ◽  
Vol 454 (3) ◽  
pp. 491-499 ◽  
Author(s):  
Anna Frick ◽  
Michael Järvå ◽  
Mikael Ekvall ◽  
Povilas Uzdavinys ◽  
Maria Nyblom ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Lipid Bilayer ◽  
Water Transport ◽  
Water Permeability ◽  
Environmental Changes ◽  
Spinacia Oleracea ◽  
Cysteine Residues ◽  
Plasma Membrane Intrinsic Protein ◽  
Plant Plasma Membrane

Water transport across cellular membranes is mediated by a family of membrane proteins known as AQPs (aquaporins). AQPs were first discovered on the basis of their ability to be inhibited by mercurial compounds, an experiment which has followed the AQP field ever since. Although mercury inhibition is most common, many AQPs are mercury insensitive. In plants, regulation of AQPs is important in order to cope with environmental changes. Plant plasma membrane AQPs are known to be gated by phosphorylation, pH and Ca2+. We have previously solved the structure of the spinach AQP SoPIP2;1 (Spinacia oleracea plasma membrane intrinsic protein 2;1) in closed and open conformations and proposed a mechanism for how this gating can be achieved. To study the effect of mercury on SoPIP2;1 we solved the structure of the SoPIP2;1–mercury complex and characterized the water transport ability using proteoliposomes. The structure revealed mercury binding to three out of four cysteine residues. In contrast to what is normally seen for AQPs, mercury increased the water transport rate of SoPIP2;1, an effect which could not be attributed to any of the cysteine residues. This indicates that other factors might influence the effect of mercury on SoPIP2;1, one of which could be the properties of the lipid bilayer.

scholarly journals Interaction between the barley allelochemical compounds gramine and hordenine and artificial lipid bilayers mimicking the plant plasma membrane

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Simon Lebecque ◽  
Jean-Marc Crowet ◽  
Laurence Lins ◽  
Benjamin M. Delory ◽  
Patrick du Jardin ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Bilayers ◽  
Artificial Lipid Bilayers ◽  
Plant Plasma Membrane
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