scholarly journals Pseudomonas syringae effector HopZ3 suppresses the bacterial AvrPto1–tomato PTO immune complex via acetylation

2021 ◽  
Vol 17 (11) ◽  
pp. e1010017
Author(s):  
Joanna Jeleńska ◽  
Jiyoung Lee ◽  
Andrew J. Manning ◽  
Donald J. Wolfgeher ◽  
Youngjoo Ahn ◽  
...  
Keyword(s):  
Immune Complex ◽  
Pseudomonas Syringae ◽  
Immune Complexes ◽  
Site Directed Mutagenesis ◽  
Host Proteins ◽  
Susceptibility To Infection ◽  
Binding Interface ◽  
Lysine Residues ◽  
Increased Susceptibility

The plant pathogen Pseudomonas syringae secretes multiple effectors that modulate plant defenses. Some effectors trigger defenses due to specific recognition by plant immune complexes, whereas others can suppress the resulting immune responses. The HopZ3 effector of P. syringae pv. syringae B728a (PsyB728a) is an acetyltransferase that modifies not only components of plant immune complexes, but also the Psy effectors that activate these complexes. In Arabidopsis, HopZ3 acetylates the host RPM1 complex and the Psy effectors AvrRpm1 and AvrB3. This study focuses on the role of HopZ3 during tomato infection. In Psy-resistant tomato, the main immune complex includes PRF and PTO, a RIPK-family kinase that recognizes the AvrPto effector. HopZ3 acts as a virulence factor on tomato by suppressing AvrPto1Psy-triggered immunity. HopZ3 acetylates AvrPto1Psy and the host proteins PTO, SlRIPK and SlRIN4s. Biochemical reconstruction and site-directed mutagenesis experiments suggest that acetylation acts in multiple ways to suppress immune signaling in tomato. First, acetylation disrupts the critical AvrPto1Psy-PTO interaction needed to initiate the immune response. Unmodified residues at the binding interface of both proteins and at other residues needed for binding are acetylated. Second, acetylation occurs at residues important for AvrPto1Psy function but not for binding to PTO. Finally, acetylation reduces specific phosphorylations needed for promoting the immune-inducing activity of HopZ3’s targets such as AvrPto1Psy and PTO. In some cases, acetylation competes with phosphorylation. HopZ3-mediated acetylation suppresses the kinase activity of SlRIPK and the phosphorylation of its SlRIN4 substrate previously implicated in PTO-signaling. Thus, HopZ3 disrupts the functions of multiple immune components and the effectors that trigger them, leading to increased susceptibility to infection. Finally, mass spectrometry used to map specific acetylated residues confirmed HopZ3’s unusual capacity to modify histidine in addition to serine, threonine and lysine residues.

Experimental Otitis Media with Effusion: An Immune-Complex-Mediated Response

1978 ◽  
Vol 86 (2) ◽  
pp. ORL-258-ORL-268 ◽  
Author(s):  
Joseph Mravec ◽  
Daniel M. Lewis ◽  
David J. Lim
Keyword(s):  
Otitis Media ◽  
Immune Complex ◽  
Immune Complexes ◽  
Polymorphonuclear Leukocytes ◽  
Capillary Permeability ◽  
Otitis Media With Effusion ◽  
Time Intervals ◽  
Etiologic Role ◽  
Inflammatory Changes

The possibility that immune complexes cause otitis media with effusion (OME) has been previously proposed. In order to test this hypothesis we developed an animal model in which immune complexes were injected into the middle ears of chinchillas and the animals killed at various time intervals thereafter. Moderate inflammatory changes were seen in animals killed four hours postinjection, whereas intense inflammation was observed in those killed at 24 hours. Inflammatory changes observed included capillary dilatation with increased capillary permeability, migration of polymorphonuclear leukocytes into the submucosa, hemorrhage, and damage to and actual disruption of the subepithelial basement membrane. These changes are consistent with a complement-mediated acute inflammatory reaction. Although no definite conclusion can be made concerning the etiologic role of immune complex in OME, our findings show that immune complexes can cause acute inflammatory changes in the middle ear of the experimental animal.

scholarly journals Role of Immune Complex Size and Complement Binding in Regulating Monocyte Responses to Immune Complexes • 1982

1998 ◽  
Vol 43 ◽  
pp. 338-338
Author(s):  
James N Jarvis ◽  
Wenlian Wang ◽  
Alit Amit ◽  
ChengSu Xu
Keyword(s):  
Immune Complex ◽  
Immune Complexes

Role of positive charge of lysine residue on cytochrome c3 for electrostatic interaction with hydrogenase

2007 ◽  
Vol 11 (01) ◽  
pp. 66-73
Author(s):  
Shin Iida ◽  
Noriyuki Asakura ◽  
Kenji Tabata ◽  
Ichiro Okura ◽  
Toshiaki Kamachi
Keyword(s):  
Electron Transfer ◽  
Cytochrome C ◽  
Hydrogen Evolution ◽  
Electrostatic Interaction ◽  
Positive Charge ◽  
Lysine Residue ◽  
Site Directed Mutagenesis ◽  
Desulfovibrio Vulgaris ◽  
Lysine Residues

Cytochrome c3 from Desulfovibrio vulgaris (Miyazaki) is an electron transfer protein containing four hemes per molecule. Its physiological electron transfer partner is the hydrogenase which catalyzes reversible oxidation of hydrogen. The complex formation between cytochrome c3 and hydrogenase is caused by electrostatic interaction, because cytochrome c3 is a basic protein and hydrogenase is an acidic protein. As cytochrome c3 has 20 lysine residues among 108 amino acids, the positive charges of some lysine residues may play an important role in the interaction with hydrogenase. To clarify the role of positive charge of lysine residue, the positive charge was changed to neutral or negative charge using chemical modification and site-directed mutagenesis. When the positive charges around heme IV were changed, the hydrogen evolution rate with hydrogenase decreased. The affinity between hydrogenase and mutated cytochrome c3 (K57Q, K57E, K72Q, K94Q, K94E) were not affected. On the other hand, the affinity of K72E cytochrome c3 for hydrogenase was very low. These results suggest that the positive charge around heme IV plays an important role in the electrostatic interaction with hydrogenase in hydrogen evolution.

scholarly journals Role of the caspase-1 inflammasome in Salmonella typhimurium pathogenesis

2006 ◽  
Vol 203 (6) ◽  
pp. 1407-1412 ◽  
Author(s):  
Maria Lara-Tejero ◽  
Fayyaz S. Sutterwala ◽  
Yasunori Ogura ◽  
Ethan P. Grant ◽  
John Bertin ◽  
...  
Keyword(s):  
Salmonella Typhimurium ◽  
Proinflammatory Cytokines ◽  
Bacterial Infections ◽  
Oral Infection ◽  
Susceptibility To Infection ◽  
Caspase 1 ◽  
Increased Susceptibility

Caspase-1 is activated by a variety of stimuli after the assembly of the “inflammasome,” an activating platform made up of a complex of the NOD-LRR family of proteins. Caspase-1 is required for the secretion of proinflammatory cytokines, such as interleukin (IL)-1β and IL-18, and is involved in the control of many bacterial infections. Paradoxically, however, its absence has been reported to confer resistance to oral infection by Salmonella typhimurium. We show here that absence of caspase-1 or components of the inflammasome does not result in resistance to oral infection by S. typhimurium, but rather, leads to increased susceptibility to infection.

Role ofN-glycosylation in cell surface expression and protection against proteolysis of the intestinal anion exchanger SLC26A3

2012 ◽  
Vol 302 (5) ◽  
pp. C781-C795 ◽  
Author(s):  
Hisayoshi Hayashi ◽  
Yukari Yamashita
Keyword(s):  
Cell Surface ◽  
Surface Expression ◽  
Site Directed Mutagenesis ◽  
Tryptic Digestion ◽  
Cell Surface Expression ◽  
Transport Activity ◽  
Biochemical Modification ◽  
Glycosylation Sites ◽  
Increased Susceptibility

SLC26A3 is a Cl−/HCO3−exchanger that plays a major role in Cl−absorption from the intestine. Its mutation causes congenital chloride-losing diarrhea. It has been shown that SLC26A3 are glycosylated, with the attached carbohydrate being extracellular and perhaps modulating function. However, the role of glycosylation has yet to be clearly determined. We used the approaches of biochemical modification and site-directed mutagenesis to prevent glycosylation. Deglycosylation experiments with glycosidases indicated that the mature glycosylated form of SLC26A3 exists at the plasma membrane, and a putative large second extracellular loop contains all of the N-linked carbohydrates. Deglycosylation of SLC26A3 causes depression of transport activity compared with wild-type, although robust intracellular pH changes were still observed, suggesting that N-glycosylation is not absolutely necessary for transport activity. To localize glycosylation sites, we mutated the five consensus sites by replacing asparagine (N) with glutamine. Immnoblotting suggests that SLC26A3 is glycosylated at N153, N161, and N165. Deglycosylation of SLC26A3 causes a defect in cell surface processing with decreased cell surface expression. We also assessed whether SLC26A3 is protected from tryptic digestion. While the mature glycosylated SLC26A3 showed little breakdown after treatment with trypsin, deglycosylated SLC26A3 exhibited increased susceptibility to trypsin, suggesting that the oligosaccharides protect SLC26A3 from tryptic digestion. In conclusion, our data indicate that N-glycosylation of SLC26A3 is important for cell surface expression and for protection from proteolytic degradation that may contribute to the understanding of pathogenesis of congenital disorders of glycosylation.

scholarly journals Differential N-end rule degradation of RIN4/NOI fragments generated by the AvrRpt2 effector protease

2019 ◽  
Author(s):  
Kevin Goslin ◽  
Lennart Eschen-Lippold ◽  
Christin Naumann ◽  
Eric Linster ◽  
Maud Sorel ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Host Proteins ◽  
Protein Fragments ◽  
Effector Triggered Immunity ◽  
Bona Fide ◽  
Resistance Protein ◽  
Domain Protein ◽  
Physiological Substrates

AbstractThe protein RPM1-INTERACTING PROTEIN4 (RIN4) is a central regulator of both layers of plant immunity systems, the so-called pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). RIN4 is targeted by several effectors, including thePseudomonas syringaeprotease effector AvrRpt2. Cleavage of RIN4 by AvrRpt2 generates unstable RIN4 fragments, whose degradation leads to the activation of the resistance protein RPS2 (RESISTANT TO P. SYRINGAE2). Hence, identifying the determinants of RIN4 degradation is key to understanding RPS2-mediated ETI, as well as virulence functions of AvrRpt2. In addition to RIN4, AvrRpt2 cleaves host proteins from the nitrate-induced (NOI) domain family. Although cleavage of NOI-domain proteins by AvrRpt2 may contribute to PTI regulation, the (in)stability of these proteolytic fragments and the determinants that regulate their stability have not been examined. Notably, a common feature of RIN4 and of many NOI-domain protein fragments generated by AvrRpt2 cleavage is the exposure of a new N-terminal residue that is destabilizing according to the N-end rule. Using antibodies raised against endogenous RIN4, we show that the destabilization of AvrRpt2-cleaved RIN4 fragments is independent of the N-end rule pathway (recently renamed N-degron pathway). By contrast, several NOI-domain protein fragments arebona fidesubstrates of the N-degron pathway. The discovery of this novel set of substrates considerably expands the number of proteins targeted for degradation by this ubiquitin-dependent pathway, for which very few physiological substrates are known in plants. Our results also open new avenues of research to understand the role of AvrRpt2 in promoting bacterial virulence.One sentence summaryAnalysis of RIN4/NOI fragments released after cleavage by the bacterial effector protease AvrRpt2 reveals a novel role of the N-end rule in the degradation of NOI-domain proteins, but not of RIN4.

scholarly journals PAMP-INDUCED SECRETED PEPTIDE 3 (PIP3) modulates immunity in Arabidopsis thaliana

2019 ◽  
Author(s):  
Javad Najafi ◽  
Tore Brembu ◽  
Ane Kjersti Vie ◽  
Rannveig Viste ◽  
Per Winge ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Plant Defence ◽  
Fine Tuning ◽  
Callose Deposition ◽  
Modified Peptides ◽  
Defence Responses ◽  
Plant Defence Responses ◽  
Increased Susceptibility

Abstract Small post-translationally modified peptides are important signalling components of plant defence responses against phytopathogens, acting both as positive and negative modulators. PAMP-INDUCED SECRETED PEPTIDE (PIP) 1 and 2 has been shown to amplify plant immunity. Here we investigate the role of the related peptide PIP3 in the regulation of immune response in Arabidopsis. Treatment with synthetic PIP peptides led to similar transcriptome reprogramming, indicating an effect on innate immunity-related processes and phytohormones, including jasmonic acid (JA) biosynthesis and signalling. PIP3 overexpressing (OX) plants showed enhanced growth inhibition in response to flg22 exposure. In addition, flg22-induced production of reactive oxygen species and callose deposition were significantly reduced in PIP3-OX plants. Interestingly, PIP3-OX plants showed increased susceptibility both toward Botrytis cinerea and the biotrophic pathogen Pseudomonas syringae. Expression of both JA and salicylic acid biosynthesis and signalling genes was more induced during B. cinerea infection in PIP3-OX plants compared with wild-type plants. Promoter and ChIP-seq analyses indicated that the transcription factors WRKY18, WRKY33 and WRKY40 cooperatively act as repressors for PIP3. The results point to a fine-tuning role for PIP3 in modulation of immunity through the regulation of SA and JA biosynthesis and signalling pathways in Arabidopsis.

scholarly journals Differential Enhancement of Dengue Virus Immune Complex Infectivity Mediated by Signaling-Competent and Signaling-Incompetent Human FcγRIA (CD64) or FcγRIIA (CD32)

2006 ◽  
Vol 80 (20) ◽  
pp. 10128-10138 ◽  
Author(s):  
W. W. Shanaka I. Rodrigo ◽  
Xia Jin ◽  
Shanley D. Blackley ◽  
Robert C. Rose ◽  
Jacob J. Schlesinger
Keyword(s):  
Dengue Virus ◽  
Immune Complex ◽  
Immune Complexes ◽  
Plaque Assay ◽  
Site Directed Mutagenesis ◽  
Tyrosine Residues ◽  
Discernible Effect ◽  
Significant Impairment ◽  
Activation Motif ◽  
Do So

ABSTRACT Fcγ receptor (FcγR)-mediated entry of infectious dengue virus immune complexes into monocytes/macrophages is hypothesized to be a key event in the pathogenesis of complicated dengue fever. FcγRIA (CD64) and FcγRIIA (CD32), which predominate on the surface of such dengue virus-permissive cells, were compared for their influence on the infectivity of dengue 2 virus immune complexes formed with human dengue virus antibodies. A signaling immunoreceptor tyrosine-based activation motif (ITAM) incorporated into the accessory γ-chain subunit that associates with FcγRIA and constitutively in FcγRIIA is required for phagocytosis mediated by these receptors. To determine whether FcγRIA and FcγRIIA activation functions are also required for internalization of infectious dengue virus immune complexes, we generated native and signaling-incompetent versions of each receptor by site-directed mutagenesis of ITAM tyrosine residues. Plasmids designed to express these receptors were transfected into COS-7 cells, and dengue virus replication was measured by plaque assay and flow cytometry. We found that both receptors mediated enhanced dengue virus immune complex infectivity but that FcγRIIA appeared to do so far more effectively. Abrogation of FcγRIA signaling competency, either by expression without γ-chain or by coexpression with γ-chain mutants, was associated with significant impairment of phagocytosis and of dengue virus immune complex infectivity. Abrogation of FcγRIIA signaling competency was also associated with equally impaired phagocytosis but had no discernible effect on dengue virus immune complex infectivity. These findings point to fundamental differences between FcγRIA and FcγRIIA with respect to their immune-enhancing capabilities and suggest that different mechanisms of dengue virus immune complex internalization may operate between these FcγRs.

Sign in / Sign up

Export Citation Format

Share Document