scholarly journals The Small GTPase OsRac1 forms two distinct immune receptor complexes containing the PRR OsCERK1 and the NLR Pit

2020 ◽  
Author(s):  
Akira Akamatsu ◽  
Masayuki Fujiwara ◽  
Satoshi Hamada ◽  
Megumi Wakabayashi ◽  
Ai Yao ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Protein Complex ◽  
Small Gtpase ◽  
Surface Pattern ◽  
Transport Systems ◽  
Large Protein ◽  
Pathogen Invasion ◽  
Receptor Complexes ◽  
Immune Receptors ◽  
Different Types

AbstractPlants employ two different types of immune receptors, cell surface pattern recognition receptors (PRRs) and intracellular nucleotide-binding and Leucine-rich repeat-containing proteins (NLRs), to cope with pathogen invasion. Both immune receptors often share similar downstream components and responses but it remains unknown whether a PRR and an NLR assemble into the same protein complex or two distinct receptor complexes. We have previously found that the small GTPase OsRac1 plays key roles in the signaling of OsCERK1, a PRR for fungal chitin, and of Pit, an NLR for rice blast fungus, and associates directly and indirectly with both of these immune receptors. In this study, using biochemical and bioimaging approaches, we reveal that OsRac1 formed two distinct receptor complexes with OsCERK1 and with Pit. Supporting this result, OsCERK1 and Pit utilized different transport systems for anchorage to the plasma membrane. Activation of OsCERK1 and Pit led to OsRac1 activation and, concomitantly, OsRac1 shifted from a small to a large protein complex fraction. We also found that the chaperone Hsp90 contributed to the proper transport of Pit to the plasma membrane and the immune induction of Pit. These findings illuminate how the PRR OsCERK1 and the NLR Pit orchestrate rice immunity through the small GTPase OsRac1.

scholarly journals The Small GTPase OsRac1 Forms Two Distinct Immune Receptor Complexes Containing the PRR OsCERK1 and the NLR Pit

2021 ◽  
Author(s):  
Akira Akamatsu ◽  
Masayuki Fujiwara ◽  
Satoshi Hamada ◽  
Megumi Wakabayashi ◽  
Ai Yao ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Protein Complex ◽  
Small Gtpase ◽  
Surface Pattern ◽  
Transport Systems ◽  
Large Protein ◽  
Pathogen Invasion ◽  
Receptor Complexes ◽  
Immune Receptors ◽  
Different Types

Abstract Plants employ two different types of immune receptors, cell surface pattern recognition receptors (PRRs) and intracellular nucleotide-binding and leucine-rich repeat-containing proteins (NLRs), to cope with pathogen invasion. Both immune receptors often share similar downstream components and responses but it remains unknown whether a PRR and an NLR assemble into the same protein complex or two distinct receptor complexes. We have previously found that the small GTPase OsRac1 plays key roles in the signaling of OsCERK1, a PRR for fungal chitin, and of Pit, an NLR for rice blast fungus, and associates directly and indirectly with both of these immune receptors. In this study, using biochemical and bioimaging approaches, we revealed that OsRac1 formed two distinct receptor complexes with OsCERK1 and with Pit. Supporting this result, OsCERK1 and Pit utilized different transport systems for anchorage to the plasma membrane. Activation of OsCERK1 and Pit led to OsRac1 activation and, concomitantly, OsRac1 shifted from a small to a large protein complex fraction. We also found that the chaperone Hsp90 contributed to the proper transport of Pit to the plasma membrane and the immune induction of Pit. These findings illuminate how the PRR OsCERK1 and the NLR Pit orchestrate rice immunity through the small GTPase OsRac1.

scholarly journals Time-gated confocal microscopy reveals accumulation of exocyst subunits at the plant-pathogen interface

2019 ◽  
Author(s):  
Elysa J R Overdijk ◽  
Han Tang ◽  
Jan Willem Borst ◽  
Francine Govers ◽  
Tijs Ketelaar
Keyword(s):  
Plasma Membrane ◽  
Confocal Microscopy ◽  
Plant Development ◽  
Plant Pathogen ◽  
Protein Complex ◽  
Physcomitrella Patens ◽  
Phytophthora Capsici ◽  
Pathogen Invasion ◽  
Pathogen Attack ◽  
Polarized Exocytosis

Abstract Polarized exocytosis is essential for plant development and defence. The exocyst, an octameric protein complex that tethers exocytotic vesicles to the plasma membrane, targets exocytosis. Upon pathogen attack, secreted materials form papillae to halt pathogen penetration. To determine if the exocyst is directly involved in targeting exocytosis to infection sites, information about its localization is instrumental. Here, we investigated exocyst subunit localization in the moss Physcomitrella patens upon pathogen attack and infection by Phytophthora capsici. Time-gated confocal microscopy was used to eliminate autofluorescence of deposited material around infection sites allowing the visualization of the subcellular localization of exocyst subunits and of v-SNARE Vamp72A1-labeled exocytotic vesicles during infection. This showed that exocyst subunits Sec3a, Sec5b, Sec5d and Sec6 accumulated at sites of attempted pathogen penetration. Upon pathogen invasion, the exocyst subunits accumulated on the membrane surrounding papilla-like structures and hyphal encasements. Vamp72A1-labeled vesicles were found to localize in the cytoplasm around infection sites. The re-localization of exocyst subunits to infection sites suggests that the exocyst is directly involved in facilitating polarized exocytosis during pathogenesis.

Movement of Calcium Ions and their Role in the Activation of Platelets

1978 ◽  
Vol 40 (02) ◽  
pp. 212-218 ◽  
Author(s):  
P Massini ◽  
R Käser-Glanzmann ◽  
E F Lüscher
Keyword(s):  
Plasma Membrane ◽  
Platelet Activation ◽  
Calcium Ions ◽  
Binding Sites ◽  
Shape Change ◽  
Release Reaction ◽  
Dense Bodies ◽  
Activated Platelets ◽  
Different Types ◽  
Ca Ions

SummaryThe increase of the cytoplasmic Ca-concentration plays a central role in the initiation of platelet activation. Four kinds of movements of Ca-ions are presumed to occur during this process: a) Ca-ions liberated from membranes induce the rapid shape change, b) Vesicular organelles release Ca-ions into the cytoplasm which initiate the release reaction, c) The storage organelles called dense bodies, secrete their contents including Ca-ions to the outside during the release reaction, d) At the same time a rearrangement of the plasma membrane occurs, resulting in an increase in its permeability for Ca-ions as well as in an increase in the number of Ca-binding sites.Since most processes occurring during platelet activation are reversible, the platelet must be equipped with a mechanism which removes Ca-ions from the cytoplasm. A vesicular fraction obtained from homogenized platelets indeed accumulates Ca actively. This Ca- pump is stimulated by cyclic AMP and protein kinase; it may be involved in the recovery of platelets after activation.It becomes increasingly clear that the various manifestations of platelet activation are triggered by a rise in the cytoplasmic Ca2+-concentration. The evidence for this and possible mechanisms involved are discussed in some detail in the contributions by Detwiler et al. and by Gerrard and White to this symposium. In this article we shall discuss four different types of mobilization of Ca-ions which occur in the course of the activation of platelets. In addition, at least one transport step involved in the removal of Ca2+ must occur during relaxation of activated platelets.

scholarly journals Plasma Membrane Receptor Complexes

2008 ◽  
Vol 147 (4) ◽  
pp. 1560-1564 ◽  
Author(s):  
José Aker ◽  
Sacco C. de Vries
Keyword(s):  
Plasma Membrane ◽  
Membrane Receptor ◽  
Receptor Complexes ◽  
Plasma Membrane Receptor

scholarly journals Cooperative assembly of a four-molecule signaling complex formed upon T cell antigen receptor activation

2018 ◽  
Vol 115 (51) ◽  
pp. E11914-E11923 ◽  
Author(s):  
Asit Manna ◽  
Huaying Zhao ◽  
Junya Wada ◽  
Lakshmi Balagopalan ◽  
Harichandra D. Tagad ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
T Cell ◽  
Protein Complex ◽  
Antigen Receptor ◽  
Receptor Activation ◽  
T Cell Antigen Receptor ◽  
Cell Antigen Receptor ◽  
Cell Antigen ◽  
Phospholipase Cγ1 ◽  
Quaternary Complex

The T cell antigen receptor encounters foreign antigen during the immune response. Receptor engagement leads to activation of specific protein tyrosine kinases, which then phosphorylate multiple enzymes and adapter proteins. One such enzyme, phospholipase-Cγ1, is responsible for cleavage of a plasma membrane lipid substrate, a phosphoinositide, into two second messengers, diacylglycerol, which activates several enzymes including protein kinase C, and an inositol phosphate, which induces intracellular calcium elevation. In T cells, phospholipase-Cγ1 is recruited to the plasma membrane as part of a four-protein complex containing three adapter molecules. We have used recombinant proteins and synthetic phosphopeptides to reconstitute this quaternary complex in vitro. Extending biophysical tools to study concurrent interactions of the four protein components, we demonstrated the formation and determined the composition of the quaternary complex using multisignal analytical ultracentrifugation, and we characterized the thermodynamic driving forces of assembly by isothermal calorimetry. We demonstrate that the four proteins reversibly associate in a circular arrangement of binding interfaces, each protein interacting with two others. Three interactions are of high affinity, and the fourth is of low affinity, with the assembly of the quaternary complex exhibiting significant enthalpy–entropy compensation as in an entropic switch. Formation of this protein complex enables subsequent recruitment of additional molecules needed to activate phospholipase-Cγ1. Understanding the formation of this complex is fundamental to full characterization of a central pathway in T cell activation. Such knowledge is critical to developing ways in which this pathway can be selectively inhibited.

scholarly journals RGS4 and RGS2 Bind Coatomer and Inhibit COPI Association with Golgi Membranes and Intracellular Transport

2000 ◽  
Vol 11 (9) ◽  
pp. 3155-3168 ◽  
Author(s):  
Brandon M. Sullivan ◽  
Kimberly J. Harrison-Lavoie ◽  
Vladimir Marshansky ◽  
Herbert Y. Lin ◽  
John H. Kehrl ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Intracellular Transport ◽  
Gel Filtration ◽  
Inhibitory Effect ◽  
Small Gtpase ◽  
Rgs Proteins ◽  
Placental Alkaline Phosphatase ◽  
Protein Signaling ◽  
Golgi Membranes

COPI, a protein complex consisting of coatomer and the small GTPase ARF1, is an integral component of some intracellular transport carriers. The association of COPI with secretory membranes has been implicated in the maintenance of Golgi integrity and the normal functioning of intracellular transport in eukaryotes. The regulator of G protein signaling, RGS4, interacted with the COPI subunit β′-COP in a yeast two-hybrid screen. Both recombinant RGS4 and RGS2 bound purified recombinant β′-COP in vitro. Endogenous cytosolic RGS4 from NG108 cells and RGS2 from HEK293T cells cofractionated with the COPI complex by gel filtration. Binding of β′-COP to RGS4 occurred through two dilysine motifs in RGS4, similar to those contained in some aminoglycoside antibiotics that are known to bind coatomer. RGS4 inhibited COPI binding to Golgi membranes independently of its GTPase-accelerating activity on Giα. In RGS4-transfected LLC-PK1 cells, the amount of COPI in the Golgi region was considerably reduced compared with that in wild-type cells, but there was no detectable difference in the amount of either Golgi-associated ARF1 or the integral Golgi membrane protein giantin, indicating that Golgi integrity was preserved. In addition, RGS4 expression inhibited trafficking of aquaporin 1 to the plasma membrane in LLC-PK1 cells and impaired secretion of placental alkaline phosphatase from HEK293T cells. The inhibitory effect of RGS4 in these assays was independent of GTPase-accelerating activity but correlated with its ability to bind COPI. Thus, these data support the hypothesis that these RGS proteins sequester coatomer in the cytoplasm and inhibit its recruitment onto Golgi membranes, which may in turn modulate Golgi–plasma membrane or intra-Golgi transport.

scholarly journals Air quality sensors in public transport stops and cross-system communication

2021 ◽  
Vol 3 (1) ◽  
pp. 5-10
Author(s):  
Dan-Marius Mustață
Keyword(s):  
Air Quality ◽  
Public Transport ◽  
Traffic Management ◽  
Transport Systems ◽  
View Point ◽  
System Communication ◽  
Warning Messages ◽  
Different Types ◽  
Cross System ◽  
State Of Art

The purpose of this article is to present a state of art implementation of air quality sensors in public transport stops. Effects on health due to different types of pollutants are summarized as well. Functional scope of the solutions, via warning messages displayed for passengers waiting at these stops, including a cross system communication between traffic management and public transport systems, are also focused. Analysis of existing sensor types from multiple view point including functions, types of measured pollutants, price ranges and comparisons are outlined.

scholarly journals An ABC transporter Wzm–Wzt catalyzes translocation of lipid-linked galactan across the plasma membrane in mycobacteria

2021 ◽  
Vol 118 (17) ◽  
pp. e2023663118
Author(s):  
Karin Savková ◽  
Stanislav Huszár ◽  
Peter Baráth ◽  
Zuzana Pakanová ◽  
Stanislav Kozmon ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Abc Transporter ◽  
Morphological Changes ◽  
Transport Systems ◽  
Host Immune System ◽  
Mycolic Acids ◽  
Cell Wall Biogenesis ◽  
Covalently Linked ◽  
High Level

Mycobacterium tuberculosis, one of the deadliest pathogens in human history, is distinguished by a unique, multilayered cell wall, which offers the bacterium a high level of protection from the attacks of the host immune system. The primary structure of the cell wall core, composed of covalently linked peptidoglycan, branched heteropolysaccharide arabinogalactan, and mycolic acids, is well known, and numerous enzymes involved in the biosynthesis of its components are characterized. The cell wall biogenesis takes place at both cytoplasmic and periplasmic faces of the plasma membrane, and only recently some of the specific transport systems translocating the metabolic intermediates between these two compartments have been characterized [M. Jackson, C. M. Stevens, L. Zhang, H. I. Zgurskaya, M. Niederweis, Chem. Rev., 10.1021/acs.chemrev.0c00869 (2020)]. In this work, we use CRISPR interference methodology in Mycobacterium smegmatis to functionally characterize an ATP-binding cassette (ABC) transporter involved in the translocation of galactan precursors across the plasma membrane. We show that genetic knockdown of the transmembrane subunit of the transporter results in severe morphological changes and the accumulation of an aberrantly long galactan precursor. Based on similarities with structures and functions of specific O-antigen ABC transporters of gram-negative bacteria [C. Whitfield, D. M. Williams, S. D. Kelly, J. Biol. Chem. 295, 10593-10609 (2020)], we propose a model for coupled synthesis and export of the galactan polymer precursor in mycobacteria.

scholarly journals Plasma membrane repairs by small GTPase Rab3a

2016 ◽  
Vol 213 (6) ◽  
pp. 613-615 ◽  
Author(s):  
Camilla Raiborg ◽  
Harald Stenmark
Keyword(s):  
Plasma Membrane ◽  
Small Gtpase ◽  
Membrane Repair ◽  
Cell Biol ◽  
Plasma Membrane Repair

Lysosomes fuse with the plasma membrane to help repair membrane lesions, but how they are positioned close to these lesions is not fully understood. Now, Encarnação et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201511093) demonstrate that the lysosomal GTPase Rab3a and its effectors orchestrate lysosome positioning and plasma membrane repair.

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