scholarly journals GABA (γ-Aminobutyric Acid) Uptake Via the GABA Permease GabP Represses Virulence Gene Expression in Pseudomonas syringae pv. tomato DC3000

2016 ◽  
Vol 29 (12) ◽  
pp. 938-949 ◽  
Author(s):  
S. L. McCraw ◽  
D. H. Park ◽  
R. Jones ◽  
M. A. Bentley ◽  
A. Rico ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acid ◽  
Pseudomonas Syringae ◽  
Aminobutyric Acid ◽  
Gaba Uptake ◽  
Acid Uptake ◽  
Natural Setting ◽  
In Planta ◽  
Tomato Dc3000 ◽  
Virulence Gene Expression

The nonprotein amino acid γ-aminobutyric acid (GABA) is the most abundant amino acid in the tomato (Solanum lycopersicum) leaf apoplast and is synthesized by Arabidopsis thaliana in response to infection by the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (hereafter called DC3000). High levels of exogenous GABA have previously been shown to repress the expression of the type III secretion system (T3SS) in DC3000, resulting in reduced elicitation of the hypersensitive response (HR) in the nonhost plant tobacco (Nicotiana tabacum). This study demonstrates that the GABA permease GabP provides the primary mechanism for GABA uptake by DC3000 and that the gabP deletion mutant ΔgabP is insensitive to GABA-mediated repression of T3SS expression. ΔgabP displayed an enhanced ability to elicit the HR in young tobacco leaves and in tobacco plants engineered to produce increased levels of GABA, which supports the hypothesis that GABA uptake via GabP acts to regulate T3SS expression in planta. The observation that P. syringae can be rendered insensitive to GABA through loss of gabP but that gabP is retained by this bacterium suggests that GabP is important for DC3000 in a natural setting, either for nutrition or as a mechanism for regulating gene expression. [Formula: see text] Copyright © 2016 The Author(s). This is an open access article distributed under the CC BY Attribution 4.0 International license .

scholarly journals Identification and Characterization of γ-Aminobutyric Acid Uptake System GabPCg(NCgl0464) in Corynebacterium glutamicum

2012 ◽  
Vol 78 (8) ◽  
pp. 2596-2601 ◽  
Author(s):  
Zhi Zhao ◽  
Jiu-Yuan Ding ◽  
Wen-hua Ma ◽  
Ning-Yi Zhou ◽  
Shuang-Jiang Liu
Keyword(s):  
Amino Acid ◽  
Corynebacterium Glutamicum ◽  
Dry Weight ◽  
Aminobutyric Acid ◽  
Gaba Uptake ◽  
Acid Uptake ◽  
Uptake System ◽  
Content Type ◽  
Gaba Transporters ◽  
New Type

ABSTRACTCorynebacterium glutamicumis widely used for industrial production of various amino acids and vitamins, and there is growing interest in engineering this bacterium for more commercial bioproducts such as γ-aminobutyric acid (GABA). In this study, aC. glutamicumGABA-specific transporter (GabPCg) encoded byncgl0464was identified and characterized. GabPCgplays a major role in GABA uptake and is essential toC. glutamicumgrowing on GABA. GABA uptake by GabPCgwas weakly competed byl-Asn andl-Gln and stimulated by sodium ion (Na+). TheKmandVmaxvalues were determined to be 41.1 ± 4.5 μM and 36.8 ± 2.6 nmol min−1(mg dry weight [DW])−1, respectively, at pH 6.5 and 34.2 ± 1.1 μM and 67.3 ± 1.0 nmol min−1(mg DW)−1, respectively, at pH 7.5. GabPCghas 29% amino acid sequence identity to a previously and functionally identified aromatic amino acid transporter (TyrP) ofEscherichia colibut low identities to the currently known GABA transporters (17% and 15% toE. coliGabP andBacillus subtilisGabP, respectively). The mutant RES167 Δncgl0464/pGXKZ9 with the GabPCgdeletion showed 12.5% higher productivity of GABA than RES167/pGXKZ9. It is concluded that GabPCgrepresents a new type of GABA transporter and is potentially important for engineering GABA-producingC. glutamicumstrains.

scholarly journals Dual Role of Auxin in Regulating Plant Defense and Bacterial Virulence Gene Expression During Pseudomonas syringae PtoDC3000 Pathogenesis

2020 ◽  
Vol 33 (8) ◽  
pp. 1059-1071 ◽  
Author(s):  
Arnaud T. Djami-Tchatchou ◽  
Gregory A. Harrison ◽  
Chris P. Harper ◽  
Renhou Wang ◽  
Michael J. Prigge ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Bacterial Growth ◽  
Plant Pathogens ◽  
Virulence Gene ◽  
Bacterial Virulence ◽  
Auxin Signaling ◽  
Host Defenses ◽  
In Planta ◽  
Virulence Gene Expression

Modification of host hormone biology is a common strategy used by plant pathogens to promote disease. For example, the bacterial pathogen strain Pseudomonas syringae DC3000 (PtoDC3000) produces the plant hormone auxin (indole-3-acetic acid [IAA]) to promote PtoDC3000 growth in plant tissue. Previous studies suggest that auxin may promote PtoDC3000 pathogenesis through multiple mechanisms, including both suppression of salicylic acid (SA)-mediated host defenses and via an unknown mechanism that appears to be independent of SA. To test if host auxin signaling is important during pathogenesis, we took advantage of Arabidopsis thaliana lines impaired in either auxin signaling or perception. We found that disruption of auxin signaling in plants expressing an inducible dominant axr2-1 mutation resulted in decreased bacterial growth and that this phenotype was suppressed by introducing the sid2-2 mutation, which impairs SA synthesis. Thus, host auxin signaling is required for normal susceptibility to PtoDC3000 and is involved in suppressing SA-mediated defenses. Unexpectedly, tir1 afb1 afb4 afb5 quadruple-mutant plants lacking four of the six known auxin coreceptors that exhibit decreased auxin perception, supported increased levels of bacterial growth. This mutant exhibited elevated IAA levels and reduced SA-mediated defenses, providing additional evidence that auxin promotes disease by suppressing host defense. We also investigated the hypothesis that IAA promotes PtoDC3000 virulence through a direct effect on the pathogen and found that IAA modulates expression of virulence genes, both in culture and in planta. Thus, in addition to suppressing host defenses, IAA acts as a microbial signaling molecule that regulates bacterial virulence gene expression.

scholarly journals Identification of Tomato Leaf Factors that Activate Toxin Gene Expression in Pseudomonas syringae pv. tomato DC3000

1998 ◽  
Vol 88 (10) ◽  
pp. 1094-1100 ◽  
Author(s):  
Xiu-Zhen Li ◽  
Alvin N. Starratt ◽  
Diane A. Cuppels
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
High Performance ◽  
Shikimic Acid ◽  
Ice Nucleation ◽  
Tomato Leaf ◽  
Toxin Gene ◽  
In Planta ◽  
Active Components ◽  
Tomato Dc3000

Coronatine is a non-host-specific chlorosis-inducing phytotoxin produced by the tomato and crucifer pathogen Pseudomonas syringae pv. tomato DC3000. How the chromosomal gene cluster controlling toxin synthesis in this strain is regulated in planta is unknown. Ice nucleation-active cor:inaZ marker-exchange derivatives of strain DC3000 were used to determine coronatine gene expression in various host and nonhost plants and in a minimal medium supplemented with selected tomato plant constituents. Ice nucleation activity, which was first detected 4 h after inoculation, was highest in cabbage, tomato, and soybean and lowest in melon and cucumber. No correlation existed between bacterial population size and expression level on the various plants. Crude tomato leaf extract and intercellular fluid were strong inducers of toxin synthesis. Based on high-performance liquid chromatography analyses and bioassays, we concluded that the active components of both preparations were malic and citric acids, with minor contributions coming from shikimic and quinic acid. Although several compounds including glucose and inositol activated the toxin genes when tested at high concentrations (3 to 5 mM), shikimic and quinic acids were the only ones with activity at concentrations below 0.1 mM. Neither acid could be used as a sole carbon source by strain DC3000. The signal activity of shikimic acid was enhanced 10-fold by the addition of glucose. None of the plant phenolics that we screened affected coronatine gene expression.

scholarly journals Dual role of auxin in regulating plant defense and bacterial virulence gene expression during Pseudomonas syringae PtoDC3000 pathogenesis

2019 ◽  
Author(s):  
Arnaud T. Djami-Tchatchou ◽  
Gregory A. Harrison ◽  
Chris P. Harper ◽  
Renhou Wang ◽  
Michael J. Prigge ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Bacterial Growth ◽  
Plant Pathogens ◽  
Virulence Gene ◽  
Bacterial Virulence ◽  
Auxin Signaling ◽  
Host Defenses ◽  
In Planta ◽  
Virulence Gene Expression

ABSTRACTModification of host hormone biology is a common strategy used by plant pathogens to promote disease. For example, the bacterial pathogen Pseudomonas syringae strain PtoDC3000 produces the plant hormone auxin (Indole-3-acetic acid, or IAA) to promote PtoDC3000 growth in plant tissue. Previous studies suggest that auxin may promote PtoDC3000 pathogenesis through multiple mechanisms, including both suppression of salicylic acid (SA)-mediated host defenses and via an unknown mechanism that appears to be independent of SA. To test if host auxin signaling is important during pathogenesis, we took advantage of Arabidopsis thaliana lines impaired in either auxin signaling or perception. We found that disruption of auxin signaling in plants expressing an inducible dominant axr2-1 mutation resulted in decreased bacterial growth, demonstrating that host auxin signaling is required for normal susceptibility to PtoDC3000, and this phenotype was dependent on SA-mediated defenses. However, despite exhibiting decreased auxin perception, tir1 afb1 afb4 afb5 quadruple mutant plants lacking four of the six known auxin co-receptors supported increased levels of bacterial growth. This mutant also exhibited elevated IAA levels, suggesting that the increased IAA in these plants may promote PtoDC3000 growth independent of host auxin signaling, perhaps through a direct effect on the pathogen. In support of this, we found that IAA directly impacted the pathogen, by modulating expression of bacterial virulence genes, both in liquid culture and in planta. Thus, in addition to suppressing host defenses, IAA acts as a microbial signaling molecule that regulates bacterial virulence gene expression.

Alginate gene expression by Pseudomonas syringae pv. tomato DC3000 in host and non-host plants

Microbiology ◽  
2003 ◽  
Vol 149 (5) ◽  
pp. 1127-1138 ◽  
Author(s):  
Ronald C. Keith ◽  
Lisa M. W. Keith ◽  
Gustavo Hernández-Guzmán ◽  
Srinivasa R. Uppalapati ◽  
Carol L. Bender
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Host Plants ◽  
Rio Grande ◽  
Histochemical Staining ◽  
Post Inoculation ◽  
Bacterial Cells ◽  
In Planta ◽  
Tomato Dc3000 ◽  
Susceptible Tomato

Pseudomonas syringae produces the exopolysaccharide alginate, a copolymer of mannuronic and guluronic acid. Although alginate has been isolated from plants infected by P. syringae, the signals and timing of alginate gene expression in planta have not been described. In this study, an algD : : uidA transcriptional fusion, designated pDCalgDP, was constructed and used to monitor alginate gene expression in host and non-host plants inoculated with P. syringae pv. tomato DC3000. When leaves of susceptible collard plants were spray-inoculated with DC3000(pDCalgDP), algD was activated within 72 h post-inoculation (p.i.) and was associated with the development of water-soaked lesions. In leaves of the susceptible tomato cv. Rio Grande-PtoS, algD activity was lower than in collard and was not associated with water-soaking. The expression of algD was also monitored in leaves of tomato cv. Rio Grande-PtoR, which is resistant to P. syringae pv. tomato DC3000. Within 12 h p.i., a microscopic hypersensitive response (micro-HR) was observed in Rio Grande-PtoR leaves spray-inoculated with P. syringae pv. tomato DC3000(pDCalgDP). As the HR progressed, histochemical staining indicated that individual bacterial cells on the surface of resistant tomato leaves were expressing algD. These results indicate that algD is expressed in both susceptible (e.g. collard, tomato) and resistant (Rio Grande-PtoR) host plants. The expression of algD in an incompatible host–pathogen interaction was further explored by monitoring transcriptional activity in leaves of tobacco, which is not a host for P. syringae pv. tomato. In tobacco inoculated with DC3000(pDCalgDP), an HR was evident within 12 h p.i., and algD expression was evident within 8-12 h p.i. However, when tobacco was inoculated with an hrcC mutant of DC3000, the HR did not occur and algD expression was substantially lower. These results suggest that signals that precede the HR may stimulate alginate gene expression in P. syringae. Histochemical staining with nitro blue tetrazolium indicated that the superoxide anion () is a signal for algD activation in planta. This study indicates that algD is expressed when P. syringae attempts to colonize both susceptible and resistant plant hosts.

Systemic CI-966, a new γ-aminobutyric acid uptake blocker, enhances γ-aminobutyric acid action in CA1 pyramidal layer in situ

1990 ◽  
Vol 68 (9) ◽  
pp. 1194-1199 ◽  
Author(s):  
U. Ebert ◽  
K. Krnjević
Keyword(s):  
Aminobutyric Acid ◽  
Gaba Uptake ◽  
Acid Uptake ◽  
Sprague Dawley ◽  
Nipecotic Acid ◽  
Ca1 Region ◽  
Stratum Pyramidale ◽  
Sprague Dawley Rats ◽  
Pyramidal Layer ◽  
Urethane Anaesthesia

A new potent, blood–brain barrier permeable γ-aminobutyric acid (GABA) uptake blocker, 1-[2-[bis[4-(trifluoromethyl)-phenyl]methoxy]ethyl]-1,2,5,6-tetrahydro-3-pyridinecarboxylic acid (CI-966) was administered systemically by i.p. injection (5 mg/kg) in Sprague–Dawley rats under urethane anaesthesia. Twenty to thirty minutes after injection there was a highly variable, but overall significant, enhancement of the inhibition of hippocampal population spikes by GABA applied by microiontophoresis in the CA1 region. Like the effect of nipecotic acid (applied locally by iontophoresis), the potentiation by CI-966 was clearest when GABA was applied in or near the stratum pyramidale where its action normally is weakest and shows the most pronounced fading. This change in GABA potency is most simply explained by a reduction in GABA uptake.Key words: GABA, muscimol, nipecotic acid, GABA-uptake blocker, epilepsy.

scholarly journals Concurrent acetylcholinesterase staining and gamma-aminobutyric acid uptake of cortical neurons in culture.

1981 ◽  
Vol 29 (2) ◽  
pp. 306-308 ◽  
Author(s):  
M M Mesulam ◽  
M Dichter
Keyword(s):  
Tissue Culture ◽  
Cortical Neurons ◽  
Gabaergic Neurons ◽  
Aminobutyric Acid ◽  
Gaba Uptake ◽  
Acid Uptake ◽  
Gamma Aminobutyric Acid ◽  
Acetylcholinesterase Staining ◽  
Culture Positive

Gamma-aminobutyric acid (GABA) uptake and acetylcholinesterase (AChE) content were demonstrated concurrently in cortical neurons grown in tissue culture. Positive reactions either for GABA uptake or for AChE content were encountered in pyramidal and stellate, as well as spindle-shaped neurons. Neither reaction was confined to a specific morphological subtype. Nearly half the neurons were negative for either reaction. Most of the remaining neurons were positive only for GABA or only for AChE. However, a subpopulation of neurons showed not only a high AChE content, but also an avid GABA uptake. Thus, four types of neurons could be identified on the basis of these two reactions. The high AChE content in some of the cortical neurons that also showed GABA uptake indicates that there are at least two distinct types of GABAergic neurons.

scholarly journals LOCALIZATION OF THE SITES OF γ-AMINOBUTYRIC ACID (GABA) UPTAKE IN LOBSTER NERVE-MUSCLE PREPARATIONS

1971 ◽  
Vol 49 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Paula M. Orkand ◽  
Edward A. Kravitz
Keyword(s):  
Amino Acid ◽  
Connective Tissue ◽  
Electron Micrographs ◽  
Aminobutyric Acid ◽  
Gaba Uptake ◽  
Tissue Cell ◽  
Connective Tissue Cell ◽  
Cell Cytoplasm ◽  
Nerve Muscle

The principal sites of γ-aminobutyric acid (GABA) uptake in lobster nerve-muscle preparations have been determined with radioautographic techniques after binding of the amino acid to proteins by aldehyde fixation. Semiquantitative studies showed that about 30% of the radioactive GABA taken into the tissue was bound to protein by fixation. Both light and electron micrographs showed dense accumulations of label over Schwann and connective tissue cell cytoplasm; muscle was lightly labeled, but axons and terminals were almost devoid of label. The possible role of Schwann and connective tissue cells in the inactivation of GABA released from inhibitory axons is discussed.

Structure–activity studies on the inhibition of γ-aminobutyric acid uptake in brain slices by compounds related to nipecotic acid

1979 ◽  
Vol 57 (6) ◽  
pp. 581-585 ◽  
Author(s):  
J. D. Wood ◽  
D. Tsui ◽  
J. W. Phillis
Keyword(s):  
Cortical Neurons ◽  
Therapeutic Potential ◽  
Brain Slices ◽  
Aminobutyric Acid ◽  
Gaba Uptake ◽  
Acid Uptake ◽  
Nipecotic Acid ◽  
Depressant Action ◽  
Methyl Derivatives ◽  
Derivatives Of

Various N-methyl derivatives of nipecotic acid and related compounds were tested as inhibitors of γ-aminobutyric acid (GABA) uptake into mini slices. N-Methylnipecotic acid, N,N-dimethyinipecotic acid, N-methylguvacine, and N-methylnicotinic acid were effective inhibitors. None of them, however, were as potent as nipecotic acid itself. All the effective inhibitors, including nipecotic acid, also inhibited the uptake of L-proline, but to a much lesser extent. Four of the test compounds produced a depressant action on cerebral cortical neurons, but even N-methylisoguvacine, the most potent in this respect, was considerably less active than GABA. None of the test compounds caused any clearly discernible changes in the gross behaviour or appearance of mice in the 1-h period following intramuscular injection. It was concluded that methylation of the N atom of nipecotic acid and its derivatives was unlikely to lead to the development of agents with greater experimental or therapeutic potential than that of nipecotic acid itself, if the action of the agent was dependent on its effects on GABA uptake.

scholarly journals The Majority of the Type III Effector Inventory of Pseudomonas syringae pv. tomato DC3000 Can Suppress Plant Immunity

2009 ◽  
Vol 22 (9) ◽  
pp. 1069-1080 ◽  
Author(s):  
Ming Guo ◽  
Fang Tian ◽  
Yashitola Wamboldt ◽  
James R. Alfano
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
In Planta ◽  
Tomato Dc3000 ◽  
Type Iii Effector ◽  
Type Iii Effectors ◽  
Type Iii ◽  
Molecular Pattern ◽  
Effector Triggered Immunity ◽  
Type Iii Protein Secretion

The Pseudomonas syringae type III protein secretion system (T3SS) and the type III effectors it injects into plant cells are required for plant pathogenicity and the ability to elicit a hypersensitive response (HR). The HR is a programmed cell death that is associated with effector-triggered immunity (ETI). A primary function of P. syringae type III effectors appears to be the suppression of ETI and pathogen-associated molecular pattern–triggered immunity (PTI), which is induced by conserved molecules on microorganisms. We reported that seven type III effectors from P. syringae pv. tomato DC3000 were capable of suppressing an HR induced by P. fluorescens(pHIR11) and have now tested 35 DC3000 type III effectors in this assay, finding that the majority of them can suppress the HR induced by HopA1. One newly identified type III effector with particularly strong HR suppression activity was HopS2. We used the pHIR11 derivative pLN1965, which lacks hopA1, in related assays and found that a subset of the type III effectors that suppressed HopA1-induced ETI also suppressed an ETI response induced by AvrRpm1 in Arabidopsis thaliana. A. thaliana plants expressing either HopAO1 or HopF2, two type III effectors that suppressed the HopA1-induced HR, were reduced in the flagellin-induced PTI response as well as PTI induced by other PAMPs and allowed enhanced in planta growth of P. syringae. Collectively, our results suggest that the majority of DC3000 type III effectors can suppress plant immunity. Additionally, the construct pLN1965 will likely be a useful tool in determining whether other type III effectors or effectors from other types of pathogens can suppress either ETI, PTI, or both.

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