Control of Endophytic Frankia Sporulation by Alnus Nodule Metabolites

A unique case of microbial symbiont capable of dormancy within its living host cells has been reported in actinorhizal symbioses. Some Frankia strains, named Sp+, are able to sporulate inside plant cells, contrarily to Sp− strains. The presence of metabolically slowed-down bacterial structures in host cells alters our understanding of symbiosis based on reciprocal benefits between both partners, and its impact on the symbiotic processes remains unknown. The present work reports a metabolomic study of Sp+ and Sp− nodules (from Alnus glutinosa), in order to highlight variabilities associated with in-planta sporulation. A total of 21 amino acids, 44 sugars and organic acids, and 213 secondary metabolites were detected using UV and mass spectrometric–based profiling. Little change was observed in primary metabolites, suggesting that in-planta sporulation would not strongly affect the primary functionalities of the symbiosis. One secondary metabolite (M27) was detected only in Sp+ nodules. It was identified as gentisic acid 5-O-β-d-xylopyranoside, previously reported as involved in plant defenses against microbial pathogens. This metabolite significantly increased Frankia in-vitro sporulation, unlike another metabolite significantly more abundant in Sp− nodules [M168 = (5R)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-β-d-glucopyranoside]. All these results suggest that the plant could play an important role in the Frankia ability to sporulate in planta and allow us to discuss a possible sanction emitted by the host against less cooperative Sp+ symbionts.

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Proteoglycans in host–pathogen interactions: molecular mechanisms and therapeutic implications

Expert Reviews in Molecular Medicine ◽

10.1017/s1462399409001367 ◽

2010 ◽

Vol 12 ◽

Cited By ~ 62

Author(s):

Allison H. Bartlett ◽

Pyong Woo Park

Keyword(s):

Cell Surface ◽

Virulence Factors ◽

Molecular Mechanisms ◽

Biological Significance ◽

Host Cells ◽

Microbial Pathogens ◽

Therapeutic Implications ◽

Core Proteins

Many microbial pathogens subvert proteoglycans for their adhesion to host tissues, invasion of host cells, infection of neighbouring cells, dissemination into the systemic circulation, and evasion of host defence mechanisms. Where studied, specific virulence factors mediate these proteoglycan–pathogen interactions, which are thus thought to affect the onset, progression and outcome of infection. Proteoglycans are composites of glycosaminoglycan (GAG) chains attached covalently to specific core proteins. Proteoglycans are expressed ubiquitously on the cell surface, in intracellular compartments, and in the extracellular matrix. GAGs mediate the majority of ligand-binding activities of proteoglycans, and many microbial pathogens elaborate cell-surface and secreted factors that interact with GAGs. Some pathogens also modulate the expression and function of proteoglycans through known virulence factors. Several GAG-binding pathogens can no longer attach to and invade host cells whose GAG expression has been reduced by mutagenesis or enzymatic treatment. Furthermore, GAG antagonists have been shown to inhibit microbial attachment and host cell entry in vitro and reduce virulence in vivo. Together, these observations underscore the biological significance of proteoglycan–pathogen interactions in infectious diseases.

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Cas, Fak and Pyk2 function in diverse signaling cascades to promote Yersinia uptake

Journal of Cell Science ◽

10.1242/jcs.115.13.2689 ◽

2002 ◽

Vol 115 (13) ◽

pp. 2689-2700 ◽

Cited By ~ 2

Author(s):

Pamela J. Bruce-Staskal ◽

Cheryl L. Weidow ◽

Jennifer J. Gibson ◽

Amy H. Bouton

Keyword(s):

Tyrosine Kinases ◽

Host Cells ◽

Microbial Pathogens ◽

Signaling Networks ◽

Rac1 Activity ◽

Morphological Defects ◽

Cell Adhesion And Migration ◽

Uptake Process ◽

Insight Into

The interplay between pathogen-encoded virulence factors and host cell signaling networks is critical for both the establishment and clearance of microbial infections. Yersinia uptake into host cells serves as an in vitro model for exploring how host cells respond to Yersinia adherence. In this study, we provide insight into the molecular nature and regulation of signaling networks that contribute to the uptake process. Using a reconstitution approach in Fak-/- fibroblasts, we have been able to specifically address the interplay between Fak, Cas and Pyk2 in this process. We show that both Fak and Cas play roles in the Yersinia uptake process and that Cas can function in a novel pathway that is independent of Fak. Fak-dependent Yersinia uptake does not appear to involve Cas-Crk signaling. By contrast, Cas-mediated uptake in the absence of Fak requires Crk as well as the protein tyrosine kinases Pyk2 and Src. In spite of these differences, the requirement for Rac1 activity is a common feature of both pathways. Furthermore, blocking the function of either Fak or Cas induces similar morphological defects in Yersinia internalization, which are manifested by incomplete membrane protrusive activity that is consistent with an inhibition of Rac1 activity. Pyk2 also functions in Yersinia uptake by macrophages, which are physiologically important for clearing Yersinia infections. Taken together, these data provide new insight into the host cellular signaling networks that are initiated upon infection with Y. pseudotuberculosis. Importantly, these findings also contribute to a better understanding of other cellular processes that involve actin remodeling, including the host response to other microbial pathogens, cell adhesion and migration.

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Characterization of In Planta—Induced Rust Genes Isolated from a Haustorium-Specific cDNA Library

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1997.10.4.427 ◽

1997 ◽

Vol 10 (4) ◽

pp. 427-437 ◽

Cited By ~ 128

Author(s):

Matthias Hahn ◽

Kurt Mendgen

Keyword(s):

Cdna Library ◽

Expression Patterns ◽

Host Cells ◽

In Planta ◽

Developmentally Regulated ◽

Uromyces Fabae ◽

Infection Structures ◽

Genes Encoding ◽

Peptidyl Prolyl Isomerases

Rust fungi are plant parasites that depend on living host tissue for growth. For invasion of leaves, dikaryotic urediospores differentiate germ tubes and infection structures that penetrate through stomata. Biotrophic growth occurs by intercellular mycelia that form haustoria within host cells. A cDNA library was constructed from haustoria isolated from broad bean leaves infected by Uromyces fabae. Differential screening revealed that a high proportion (19%) of the haustorial cDNAs are specifically expressed in planta but are not expressed, or are much weaker, in germlings or infection structures produced in vitro. A total of 31 different in planta-induced genes (PIGs) were identified. Some of the PIGs are highly expressed in haustoria. The PIGs are single or low copy number genes in the rust genome. A variety of developmentally regulated expression patterns of PIG mRNAs were observed. Sequence analysis of PIG cDNAs revealed similarities to genes encoding proteins involved in amino acid transport, thiamine biosynthesis, short-chain dehy-drogenases, metallothioneins, cytochrome P-450 monooxy-genases, and peptidyl-prolyl isomerases.

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Pseudomonas syringae effector AvrE associates with plant membrane nanodomains and binds phosphatidylinositides in vitro

10.1101/2021.07.08.451616 ◽

2021 ◽

Author(s):

Xiufang Xin ◽

Lisa Kinch ◽

Boying Cai ◽

Bradley C. Paasch ◽

Brian Kvitko ◽

...

Keyword(s):

Pseudomonas Syringae ◽

Transgenic Arabidopsis ◽

Biochemical Properties ◽

Membrane Lipid ◽

Effector Proteins ◽

Host Cells ◽

Plant Proteins ◽

In Planta ◽

Plasma Membrane Lipid

Bacterial phytopathogens deliver effector proteins into host cells as key virulence weapons to cause disease. Extensive studies revealed diverse functions and biochemical properties of different effector proteins from pathogens. In this study, we show that the Pseudomonas syringae effector AvrE, the founding member of a broadly conserved and pathologically important bacterial effector family, binds to phosphatidylinositides (PIPs) in vitro and shares some properties with eukaryotic PROPPINs (β-propellers that bind polyphosphoinositides). In planta pull down experiments with transgenic Arabidopsis plants expressing AvrE revealed that AvrE is associated with several plant proteins including plasma membrane lipid-raft proteins. These results shed new light on the properties of a bacterial effector that is crucial for bacterial virulence in plants.

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The C-terminal domain of the type III secretion chaperone HpaB contributes to dissociation of chaperone-effector complex in Xanthomonas campestris pv. campestris

PLoS ONE ◽

10.1371/journal.pone.0246033 ◽

2021 ◽

Vol 16 (1) ◽

pp. e0246033

Author(s):

Yong-Liang Gan ◽

Li-Yan Yang ◽

Li-Chao Yang ◽

Wan-Lian Li ◽

Xue-Lian Liang ◽

...

Keyword(s):

Xanthomonas Campestris ◽

Pathogenic Bacteria ◽

Terminal Region ◽

Effector Proteins ◽

Host Cells ◽

Dependent Manner ◽

In Planta ◽

Terminal Domain ◽

Self Association

Many animal and plant pathogenic bacteria employ a type three secretion system (T3SS) to deliver type three effector proteins (T3Es) into host cells. Efficient secretion of many T3Es in the plant pathogen Xanthomonas campestris pv. campestris (Xcc) relies on the global chaperone HpaB. However, how the domain of HpaB itself affects effector translocation/secretion is poorly understood. Here, we used genetic and biochemical approaches to identify a novel domain at the C-terminal end of HpaB (amino acid residues 137–160) that contributes to virulence and hypersensitive response (HR). Both in vitro secretion assay and in planta translocation assay showed that the secretion and translocation of T3E proteins depend on the C-terminal region of HpaB. Deletion of the C-terminal region of HpaB did not affect binding to T3Es, self-association or interaction with T3SS components. However, the deletion of C-terminal region sharply reduced the mounts of free T3Es liberated from the complex of HpaB with the T3Es, a reaction catalyzed in an ATP-dependent manner by the T3SS-associated ATPase HrcN. Our findings demonstrate the C-terminal domain of HpaB contributes to disassembly of chaperone-effector complex and reveal a potential molecular mechanism underpinning the involvement of HpaB in secretion of T3Es in Xcc.

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Nitric Oxide Regulates the Ralstonia solanacearum Type 3 Secretion System

10.1101/2020.10.26.355339 ◽

2020 ◽

Author(s):

Connor G. Hendrich ◽

Alicia N. Truchon ◽

Beth L. Dalsing ◽

Caitilyn Allen

Keyword(s):

Nitric Oxide ◽

Xylem Sap ◽

Nutrient Content ◽

Secretion System ◽

Host Cells ◽

In Planta ◽

Plant Host ◽

Hypoxic Environment ◽

Type 3

AbstractRalstonia solancearum causes bacterial wilt disease on diverse plant hosts. R. solanacearum cells enter a host from soil or infested water through the roots, then multiply and spread in the water-transporting xylem vessels. Despite the low nutrient content of xylem sap, R. solanacearum grows extremely well inside the host, using denitrification to respire in this hypoxic environment. R. solanacearum growth in planta also depends on the successful deployment of protein effectors into host cells using a Type III Secretion System (T3SS). The T3SS is absolutely required for R. solanacearum virulence, but it is metabolically costly and can trigger host defenses. Thus, the pathogen’s success depends on optimized regulation of the T3SS. We found that a byproduct of denitrification, the toxic free-radical nitric oxide (NO), positively regulates the R. solanacearum T3SS both in vitro and in planta. Using chemical treatments and R. solanacearum mutants with altered NO levels, we show that the expression of a key T3SS regulator is induced by NO in culture. Analyzing the transcriptome of R. solanacearum responding to varying levels of NO both in culture and in planta revealed that the T3SS and effectors were broadly upregulated with increasing levels of NO. This regulation was specific to the T3SS and was not shared by other stressors. Our results suggest that R. solanacearum experiences an NO-rich environment in the plant host and may use this NO as a signal to activate T3SS during infection.

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Synthesis and Antimicrobial Activity of Adamantyl Substituted Pyridoxine Derivatives

Letters in Drug Design & Discovery ◽

10.2174/1570180816666190911150705 ◽

2019 ◽

Vol 16 (12) ◽

pp. 1360-1369 ◽

Cited By ~ 2

Author(s):

Rail Khaziev ◽

Nikita Shtyrlin ◽

Roman Pavelyev ◽

Raushan Nigmatullin ◽

Raylya Gabbasova ◽

...

Keyword(s):

Influenza Virus ◽

Lipid Membranes ◽

Specific Activity ◽

Tuberculosis H37rv ◽

Microbial Pathogens ◽

Adamantane Derivatives ◽

Carbon Cage ◽

H37rv Strain ◽

Derivatives Of

Background: Adamantane derivatives possess multiple pharmacological activities such as antiviral, anticancer, antimycobacterial, antidiabetic, antiparkinsonian and others. The interest of medicinal chemists in adamantane compounds is due to their unique spatial structure, high lipophilicity, and carbon cage rigidity. As a result, these molecules can easily penetrate biological lipid membranes and often have unique target-specific activity profile. Another pharmacophore studied in this work is pyridoxine (vitamin B6). Pyridoxine plays highly important roles in living cells as a key cofactor of many enzymes. On the other hand, its molecular scaffold is a valuable structural platform which has led to the development of several launched drugs (Pyritinol, Pirisudanol, Cycletanine, Mangafodipir) and a wide number of preclinical and clinical drug candidates. Objective: The objective of this study is a synthesis of pyridoxine-adamantane and pyridoxinecyclooctane dipharmacophore molecules. The underlying idea was to assess the antibacterial and antiviral potential of such dipharmacophores, based on multiple examples of promising antiinfective agents which have in their structures adamantane and pyridoxine moieties. Another specific reason was to explore the ability of pyridoxine pharmacophore to suppress the potential of microbial pathogens to develop resistance to drug molecules. Methods: In this study, a series of pyridoxine-adamantane and pyridoxine-cyclooctane dipharmacophore molecules were synthesized based on reactions of three different cycloalkyl amines with the corresponding electrophilic derivatives of pyridoxine aldehydes, chlorides and acetates. All synthesized compounds have been tested for their in vitro activity against M. tuberculosis H37Rv strain and H3N2 (A/Aichi/2/68) influenza virus. Results: Series of pyridoxine-adamantane and pyridoxine-cyclooctane dipharmacophore molecules were synthesized based on reactions of three different cycloalkylamines with the corresponding electrophilic derivatives of pyridoxine aldehydes, chlorides and acetates. Reaction of cycloalkylamines with pyridoxine derivatives, in which meta-hydroxyl and ortho-hydroxymethyl groups are protected by acetyl groups, represents a useful alternative to reductive amination of aldehydes and nucleophilic substitution of alkyl halides. According to a tentative mechanism, it proceeds via paraand ortho-pyridinone methides which readily react with nucleophiles. None of the synthesized dipharmacophore compounds showed activity against M. tuberculosis H37Rv strain. At the same time, three compounds demonstrated some antiviral activity against H3N2 (A/Aichi/2/68) influenza virus (EC50 52-88 µg/mL) that was comparable to the activity of Amantadine, though lower than the activity of Rimantadine. The results of this work can be useful in the design of physiologically active derivatives of pyridoxine and adamantane. Conclusion: The results of this work can be useful in the design of physiologically active derivatives of pyridoxine and adamantane.

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Novel Toxin-antitoxin System Xn-mazEF from Xenorhabdus nematophi-la: Identification, Characterization and Functional Exploration

Current Computer - Aided Drug Design ◽

10.2174/1573409916666200625135850 ◽

2020 ◽

Vol 16 ◽

Author(s):

Jogendra Singh Nim ◽

Mohit Yadav ◽

Lalit Kumar Gautam ◽

Chaitali Ghosh ◽

Shakti Sahi ◽

...

Keyword(s):

Interaction Analysis ◽

Functional Characterization ◽

Host Cells ◽

System Control ◽

Xenorhabdus Nematophila ◽

Functional Features ◽

Dynamics Simulations ◽

Species Specific ◽

Rna Interaction

Background: Xenorhabdus nematophila maintains species-specific mutual interaction with nematodes of Steinernema genus. Type II Toxin Antitoxin (TA) systems, the mazEF TA system controls stress and programmed cell death in bacteria. Objective: This study elucidates the functional characterization of Xn-mazEF, a mazEF homolog in X. nematophila by computational and in vitro approaches. Methods: 3 D- structural models for Xn-MazE toxin and Xn-MazF antitoxin were generated, validated and characterized for protein - RNA interaction analysis. Further biological and cellular functions of Xn-MazF toxin were also predicted. Molecular dynamics simulations of 50ns for Xn-MazF toxin complexed with nucleic acid units (DU, RU, RC, and RU) were performed. The MazF toxin and complete MazEF operon were endogenously expressed and monitored for the killing of Escherichia coli host cells under arabinose induced tightly regulated system. Results: Upon induction, E. coli expressing toxin showed rapid killing within four hours and attained up to 65% growth inhibition, while the expression of the entire operon did not show significant killing. The observation suggests that the Xn-mazEF TA system control transcriptional regulation in X. nematophila and helps to manage stress or cause toxicity leading to programmed death of cells. Conclusion: The study provides insights into structural and functional features of novel toxin, XnMazF and provides an initial inference on control of X. nematophila growth regulated by TA systems.

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ACIS, A Novel KepTide™, Binds to ACE-2 Receptor and Inhibits the Infection of SARS-CoV2 Virus in vitro in Primate Kidney Cells: Therapeutic Implications for COVID-19 (Preprint)

10.2196/preprints.25089 ◽

2020 ◽

Author(s):

Avik Sotira Scientific

Keyword(s):

Social Life ◽

Plaque Assay ◽

Host Cells ◽

Surface Glycoprotein ◽

Crystallographic Structure ◽

Therapeutic Implications ◽

Biochemical Assays ◽

Targeted Medicine

UNSTRUCTURED Coronavirus disease 2019 (COVID-19) is a severe acute respiratory syndrome (SARS) caused by a virus known as SARS-Coronavirus 2 (SARS-CoV2). Without a targeted-medicine, this disease has been causing a massive humanitarian crisis not only in terms of mortality, but also imposing a lasting damage to social life and economic progress of humankind. Therefore, an immediate therapeutic strategy needs to be intervened to mitigate this global crisis. Here, we report a novel KepTide™ (Knock-End Peptide) therapy that nullifies SARS-CoV2 infection. SARS-CoV2 employs its surface glycoprotein “spike” (S-glycoprotein) to interact with angiotensin converting enzyme-2 (ACE-2) receptor for its infection in host cells. Based on our in-silico-based homology modeling study validated with a recent X-ray crystallographic structure (PDB ID:6M0J), we have identified that a conserved motif of S-glycoprotein that intimately engages multiple hydrogen-bond (H-bond) interactions with ACE-2 enzyme. Accordingly, we designed a peptide, termed as ACIS (ACE-2 Inhibitory motif of Spike), that displayed significant affinity towards ACE-2 enzyme as confirmed by biochemical assays such as BLItz and fluorescence polarization assays. Interestingly, more than one biochemical modifications were adopted in ACIS in order to enhance the inhibitory action of ACIS and hence called as KEpTide™. Consequently, a monolayer invasion assay, plaque assay and dual immunofluorescence analysis further revealed that KEpTide™ efficiently mitigated the infection of SARS-CoV2 in vitro in VERO E6 cells. Finally, evaluating the relative abundance of ACIS in lungs and the potential side-effects in vivo in mice, our current study discovers a novel KepTide™ therapy that is safe, stable, and robust to attenuate the infection of SARS-CoV2 virus if administered intranasally. INTERNATIONAL REGISTERED REPORT RR2-https://doi.org/10.1101/2020.10.13.337584

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A peroxisomal β-oxidative pathway contributes to the formation of C6–C1 aromatic volatiles in poplar

Plant Physiology ◽

10.1093/plphys/kiab111 ◽

2021 ◽

Author(s):

Nathalie D Lackus ◽

Axel Schmidt ◽

Jonathan Gershenzon ◽

Tobias G Köllner

Keyword(s):

Cinnamic Acid ◽

Aromatic Compounds ◽

Populus Trichocarpa ◽

Alternative Pathway ◽

Gene Families ◽

Defense Responses ◽

In Planta ◽

Black Cottonwood ◽

Oxidative Pathway

AbstractBenzenoids (C6–C1 aromatic compounds) play important roles in plant defense and are often produced upon herbivory. Black cottonwood (Populus trichocarpa) produces a variety of volatile and nonvolatile benzenoids involved in various defense responses. However, their biosynthesis in poplar is mainly unresolved. We showed feeding of the poplar leaf beetle (Chrysomela populi) on P. trichocarpa leaves led to increased emission of the benzenoid volatiles benzaldehyde, benzylalcohol, and benzyl benzoate. The accumulation of salicinoids, a group of nonvolatile phenolic defense glycosides composed in part of benzenoid units, was hardly affected by beetle herbivory. In planta labeling experiments revealed that volatile and nonvolatile poplar benzenoids are produced from cinnamic acid (C6–C3). The biosynthesis of C6–C1 aromatic compounds from cinnamic acid has been described in petunia (Petunia hybrida) flowers where the pathway includes a peroxisomal-localized chain shortening sequence, involving cinnamate-CoA ligase (CNL), cinnamoyl-CoA hydratase/dehydrogenase (CHD), and 3-ketoacyl-CoA thiolase (KAT). Sequence and phylogenetic analysis enabled the identification of small CNL, CHD, and KAT gene families in P. trichocarpa. Heterologous expression of the candidate genes in Escherichia coli and characterization of purified proteins in vitro revealed enzymatic activities similar to those described in petunia flowers. RNA interference-mediated knockdown of the CNL subfamily in gray poplar (Populus x canescens) resulted in decreased emission of C6–C1 aromatic volatiles upon herbivory, while constitutively accumulating salicinoids were not affected. This indicates the peroxisomal β-oxidative pathway participates in the formation of volatile benzenoids. The chain shortening steps for salicinoids, however, likely employ an alternative pathway.

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