scholarly journals A highly conserved mechanism for the detoxification and assimilation of the toxic phytoproduct L-azetidine-2-carboxylic acid in Aspergillus nidulans

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ada Biratsi ◽  
Alexandros Athanasopoulos ◽  
Vassili N. Kouvelis ◽  
Christos Gournas ◽  
Vicky Sophianopoulou
Keyword(s):  
Carboxylic Acid ◽  
Aspergillus Nidulans ◽  
Defense Mechanisms ◽  
Plant Pathogens ◽  
Animal Cells ◽  
Haloacid Dehalogenase ◽  
Filamentous Ascomycete ◽  
Had Superfamily ◽  
Phytopathogenic Microorganisms ◽  
Detoxification Process

AbstractPlants produce toxic secondary metabolites as defense mechanisms against phytopathogenic microorganisms and predators. L-azetidine-2-carboxylic acid (AZC), a toxic proline analogue produced by members of the Liliaceae and Agavaciae families, is part of such a mechanism. AZC causes a broad range of toxic, inflammatory and degenerative abnormalities in human and animal cells, while it is known that some microorganisms have evolved specialized strategies for AZC resistance. However, the mechanisms underlying these processes are poorly understood. Here, we identify a widespread mechanism for AZC resistance in fungi. We show that the filamentous ascomycete Aspergillus nidulans is able to not only resist AZC toxicity but also utilize it as a nitrogen source via GABA catabolism and the action of the AzhA hydrolase, a member of a large superfamily of detoxifying enzymes, the haloacid dehalogenase-like hydrolase (HAD) superfamily. This detoxification process is further assisted by the NgnA acetyltransferase, orthologue of Mpr1 of Saccharomyces cerevisiae. We additionally show that heterologous expression of AzhA protein can complement the AZC sensitivity of S. cerevisiae. Furthermore, a detailed phylogenetic analysis of AzhA homologues in Fungi, Archaea and Bacteria is provided. Overall, our results unravel a widespread mechanism for AZC resistance among microorganisms, including important human and plant pathogens.

scholarly journals The role of Aspergillus nidulans polo-like kinase PlkA in microtubule-organizing center control

2021 ◽  
Author(s):  
Xiaolei Gao ◽  
Saturnino Herrero ◽  
Valentin Wernet ◽  
Sylvia Erhardt ◽  
Oliver Valerius ◽  
...  
Keyword(s):  
Aspergillus Nidulans ◽  
Cell Types ◽  
Spindle Pole ◽  
Receptor Protein ◽  
Animal Cells ◽  
Microtubule Organizing Center ◽  
Spindle Pole Bodies ◽  
Organizing Center ◽  
Ring Complex ◽  
Core Components

Centrosomes are important microtubule-organizing centers (MTOC) in animal cells. In addition, non-centrosomal MTOCs (ncMTOCs) were described in many cell types. Functional analogs of centrosomes in fungi are the spindle pole bodies (SPBs). In Aspergillus nidulans additional MTOCs were discovered at septa (sMTOC). Although the core components are conserved in both MTOCs, their composition and organization are different and dynamic. Here, we show that the polo-like kinase PlkA binds the γ-tubulin ring complex (γ-TuRC) receptor protein ApsB and contributes to targeting ApsB to both MTOCs. PlkA coordinates SPB outer plaque with sMTOC activities. PlkA kinase activity was required for astral MT formation involving ApsB recruitment. PlkA also interacted with the γ-TuRC inner plaque receptor protein PcpA. Mitosis was delayed without PlkA, and the PlkA protein was required for proper mitotic spindle morphology, although this function was independent of its catalytic activity. Our results suggest polo-like kinase as a regulator of MTOC activities and as a scaffolding unit through interaction with γ-tubulin ring complex receptors.

scholarly journals Genome-wide analysis of haloacid dehalogenase genes reveals their function in phosphate starvation responses in rice

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245600
Author(s):  
Zezhen Du ◽  
Suren Deng ◽  
Zixuan Wu ◽  
Chuang Wang
Keyword(s):  
Bioinformatics Analysis ◽  
Sequence Similarity ◽  
Motif Analysis ◽  
Systematic Classification ◽  
Diverse Range ◽  
Haloacid Dehalogenase ◽  
Genome Wide ◽  
Pi Starvation ◽  
Had Superfamily ◽  
Pi Stress

The HAD superfamily is named after the halogenated acid dehalogenase found in bacteria, which hydrolyses a diverse range of organic phosphate substrates. Although certain studies have shown the involvement of HAD genes in Pi starvation responses, systematic classification and bioinformatics analysis of the HAD superfamily in plants is lacking. In this study, 41 and 40 HAD genes were identified by genomic searching in rice and Arabidopsis, respectively. According to sequence similarity, these proteins are divided into three major groups and seven subgroups. Conserved motif analysis indicates that the majority of the identified HAD proteins contain phosphatase domains. A further structural analysis showed that HAD proteins have four conserved motifs and specified cap domains. Fewer HAD genes show collinearity relationships in both rice and Arabidopsis, which is consistent with the large variations in the HAD genes. Among the 41 HAD genes of rice, the promoters of 28 genes contain Pi-responsive cis-elements. Mining of transcriptome data and qRT-PCR results showed that at least the expression of 17 HAD genes was induced by Pi starvation in shoots or roots. These HAD proteins are predicted to be involved in intracellular or extracellular Po recycling under Pi stress conditions in plants.

scholarly journals Genes and Enzymes of Azetidine-2-Carboxylate Metabolism: Detoxification and Assimilation of an Antibiotic

2008 ◽  
Vol 190 (14) ◽  
pp. 4859-4864 ◽  
Author(s):  
Carol Gross ◽  
Roderick Felsheim ◽  
Lawrence P. Wackett
Keyword(s):  
Specific Activity ◽  
Periplasmic Fraction ◽  
Gene Encoding ◽  
Haloacid Dehalogenase ◽  
Protein Mass ◽  
Protein Mass Spectrometry ◽  
Chaperone Protein ◽  
Marker Proteins ◽  
Had Superfamily ◽  
Cell Fractions

ABSTRACT l-(−)-Azetidine-2-carboxylate (AC) is a toxic, natural product analog of l-proline. This study revealed the genes and biochemical strategy employed by Pseudomonas sp. strain A2C to detoxify and assimilate AC as its sole nitrogen source. The gene region from Pseudomonas sp. strain A2C required for detoxification was cloned into Escherichia coli and sequenced. The 7.0-kb region contained eight identifiable genes. Four encoded putative transporters or permeases for γ-amino acids or drugs. Another gene encoded a homolog of 2-haloacid dehalogenase (HAD). The encoded protein, denoted l-azetidine-2-carboxylate hydrolase (AC hydrolase), was highly overexpressed by subcloning. The AC hydrolase was shown to catalyze azetidine ring opening with the production of 2-hydroxy-4-aminobutyrate. AC hydrolase was further demonstrated to be a new hydrolytic member of the HAD superfamily by showing loss of activity upon changing aspartate-12, the conserved active site nucleophile in this family, to an alanine residue. The presence of a gene encoding a potential export chaperone protein, CsaA, adjacent to the AC hydrolase gene suggested that AC hydrolase might be found inside the periplasm in the native Pseudomonas strain. Periplasmic and cytoplasmic cell fractions from Pseudomonas sp. strain A2C were prepared. A higher specific activity for AC hydrolysis was found in the periplasmic fraction. Protein mass spectrometry further identified AC hydrolase and known periplasmic marker proteins in the periplasmic fraction. A model was proposed in which AC is hydrolyzed in the periplasm and the product of that reaction is transported into and further metabolized in the cytoplasm.

scholarly journals The actin cytoskeleton mediates transmission of Candidatus Liberibacter solanacearum by the carrot psyllid

2020 ◽  
Author(s):  
Poulami Sarkar ◽  
Svetlana Kontsedalov ◽  
Galina Lebedev ◽  
Murad Ghanim
Keyword(s):  
Actin Cytoskeleton ◽  
Defense Mechanisms ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Plant Diseases ◽  
Citrus Industry ◽  
Citrus Greening Disease ◽  
Associated Diseases ◽  
Novel Approach ◽  
Vector Borne

Several vector-borne plant pathogens have evolved mechanisms to exploit and hijack vector host cellular, molecular and defense mechanisms for their transmission. Over the past few years, Liberibacter species, which are transmitted by several psyllid vectors, have become an economically important group of pathogens that devastated the citrus industry and caused tremendous losses to many other important crops worldwide. The molecular mechanisms underlying the interactions of Liberibacter species with their psyllid vectors are poorly studied. Candidatus Liberibacter solanacearum (CLso) associated with important vegetable diseases is transmitted by the carrot psyllid, Bactericera trigonica in a persistent manner. Here, we elucidated the role of B. trigonica Arp2/3 protein complex, which plays a major role in the regulation of the actin cytoskeleton, in the transmission of CLso. CLso co-localized with ArpC2, a key protein in this complex, and this co-localization strongly associated with actin filaments. Silencing the psyllid ArpC2 disrupted the co-localization and the dynamics of F-actin. Silencing RhoGAP21 and Cdc42, which act in the signaling cascade leading to upregulation of Arp2/3 and F-actin bundling, also showed similar results. On the other hand, silencing ArpC5, another component of the complex, did not induce any significant effects on F-actin formation. Finally, ArpC2 silencing caused 73.4% reduction in CLso transmission by psyllids, strongly suggesting that its transmission by B. trigonica is cytoskeleton-dependent and it interacts with ArpC2 to exploit the intracellular actin nucleation process for transmission. Targeting this unique interaction could lead to developing a novel strategy for the management of Liberibacter-associated diseases. IMPORTANCE Plant diseases caused by vector-borne pathogens are responsible for tremendous losses and threaten some of the most important agricultural crops. A good example is the citrus greening disease caused by bacteria of the genus Liberibacter and transmitted by psyllids, and has devastated the citrus industry in the US, China and Brazil. Here we show that the psyllid-transmitted Candidatus Liberibacter solanacearum (CLso) employs the actin cytoskeleton of psyllid gut cells, specifically the ArpC2 protein in the Arp2/3 complex of this system, for movement and transmission in the vector. Silencing ArpC2 dramatically influenced interaction of CLso with the cytoskeleton and decreased the bacteria transmission to plants. This system could be targeted for developing a novel approach for the control of Liberibacter- associated diseases.

Silicon Potentiates Host Defense Mechanisms Against Infection by Plant Pathogens

2015 ◽  
pp. 109-138 ◽  
Author(s):  
Fabrício A. Rodrigues ◽  
Renata Sousa Resende ◽  
Leandro José Dallagnol ◽  
Lawrence E. Datnoff
Keyword(s):  
Host Defense ◽  
Defense Mechanisms ◽  
Plant Pathogens

scholarly journals YZGD from Paenibacillus thiaminolyticus, a pyridoxal phosphatase of the HAD (haloacid dehalogenase) superfamily and a versatile member of the Nudix (nucleoside diphosphate x) hydrolase superfamily

2006 ◽  
Vol 394 (3) ◽  
pp. 665-674 ◽  
Author(s):  
Isaac M. Tirrell ◽  
Jennifer L. Wall ◽  
Christopher J. Daley ◽  
Sarah J. Denial ◽  
Frances G. Tennis ◽  
...  
Keyword(s):  
Phosphatase Activity ◽  
Pyridoxal Phosphate ◽  
Hydrolase Activity ◽  
Site Directed Mutagenesis ◽  
Nudix Hydrolase ◽  
Bivalent Metal ◽  
Haloacid Dehalogenase ◽  
Had Superfamily ◽  
Signature Sequence ◽  
Paenibacillus Thiaminolyticus

YZGD from Paenibacillus thiaminolyticus is a novel bifunctional enzyme with both PLPase (pyridoxal phosphatase) and Nudix (nucleoside diphosphate x) hydrolase activities. The PLPase activity is catalysed by the HAD (haloacid dehalogenase) superfamily motif of the enzyme, and the Nudix hydrolase activity is catalysed by the conserved Nudix signature sequence within a separate portion of the enzyme, as confirmed by site-directed mutagenesis. YZGD's phosphatase activity is very specific, with pyridoxal phosphate being the only natural substrate, while YZGD's Nudix activity is just the opposite, with YZGD being the most versatile Nudix hydrolase characterized to date. YZGD's Nudix substrates include the CDP-alcohols (CDP-ethanol, CDP-choline and CDP-glycerol), the ADP-coenzymes (NADH, NAD and FAD), ADP-sugars, TDP-glucose and, to a lesser extent, UDP- and GDP-sugars. Regardless of the Nudix substrate, one of the products is always a nucleoside monophosphate, suggesting a role in nucleotide salvage. Both the PLPase and Nudix hydrolase activities require a bivalent metal cation, but while PLPase activity is supported by Co2+, Mg2+, Zn2+ and Mn2+, the Nudix hydrolase activity is Mn2+-specific. YZGD's phosphatase activity is optimal at an acidic pH (pH 5), while YZGD's Nudix activities are optimal at an alkaline pH (pH 8.5). YZGD is the first enzyme reported to be a member of both the HAD and Nudix hydrolase superfamilies, the first PLPase to be recognized as a member of the HAD superfamily and the first Nudix hydrolase capable of hydrolysing ADP-x, CDP-x and TDP-x substrates with comparable substrate specificity.

scholarly journals SaxA-Mediated Isothiocyanate Metabolism in Phytopathogenic Pectobacteria

2016 ◽  
Vol 82 (8) ◽  
pp. 2372-2379 ◽  
Author(s):  
Cornelia U. Welte ◽  
Jamila F. Rosengarten ◽  
Rob M. de Graaf ◽  
Mike S. M. Jetten
Keyword(s):  
Defense Mechanisms ◽  
Plant Pathogens ◽  
Carbonyl Sulfide ◽  
Food Preservation ◽  
Beta Lactam ◽  
Content Type ◽  
Beta Lactam Antibiotics ◽  
The Family ◽  
Class B ◽  
Phenylethyl Isothiocyanate

ABSTRACTPectobacteria are devastating plant pathogens that infect a large variety of crops, including members of the family Brassicaceae. To infect cabbage crops, these plant pathogens need to overcome the plant's antibacterial defense mechanisms, where isothiocyanates are liberated by hydrolysis of glucosinolates. Here, we found that aPectobacteriumisolate from the gut of cabbage root fly larvae was particularly resistant to isothiocyanate and even seemed to benefit from the abundantBrassicaroot metabolite 2-phenylethyl isothiocyanate as a nitrogen source in an ecosystem where nitrogen is scarce. ThePectobacteriumisolate harbored a naturally occurring mobile plasmid that contained asaxoperon. We hypothesized that SaxA was the enzyme responsible for the breakdown of 2-phenylethyl isothiocyanate. Subsequently, we heterologously produced and purified the SaxA protein and characterized the recombinant enzyme. It hydrolyzed 2-phenylethyl isothiocyanate to yield the products carbonyl sulfide and phenylethylamine. It was also active toward another aromatic isothiocyanate but hardly toward aliphatic isothiocyanates. It belongs to the class B metal-dependent beta-lactamase fold protein family but was not, however, able to hydrolyze beta-lactam antibiotics. We discovered that several copies of thesaxAgene are widespread in full and draftPectobacteriumgenomes and therefore hypothesize that SaxA might be a new pathogenicity factor of the genusPectobacterium, possibly compromising food preservation strategies using isothiocyanates.

scholarly journals The Ethylene Biosynthesis Genes ACS2 and ACS6 Modulate Disease Severity of Verticillium dahliae

Plants ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 907 ◽  
Author(s):  
Eirini G. Poulaki ◽  
Maria-Dimitra Tsolakidou ◽  
Danai Gkizi ◽  
Iakovos S. Pantelides ◽  
Sotirios E. Tjamos
Keyword(s):  
Carboxylic Acid ◽  
Disease Severity ◽  
Verticillium Dahliae ◽  
Plant Pathogens ◽  
Quantitative Polymerase Chain Reaction ◽  
Polymerase Chain Reaction Analysis ◽  
Competitive Inhibitor ◽  
Ethylene Biosynthesis ◽  
Aminooxyacetic Acid ◽  
Broad Host Range

Verticillium dahliae is one of the most destructive soilborne plant pathogens since it has a broad host range and there is no chemical disease management. Therefore, there is a need to unravel the molecular interaction between the pathogen and the host plant. For this purpose, we examined the role of 1-aminocyclopropane-1-carboxylic acid synthases (ACSs) of Arabidopsis thaliana upon V. dahliae infection. We observed that the acs2, acs6, and acs2/6 plants are partially resistant to V. dahliae, since the disease severity of the acs mutants was lower than the wild type (wt) Col-0 plants. Quantitative polymerase chain reaction analysis revealed that acs2, acs6, and acs2/6 plants had lower endophytic levels of V. dahliae than the wt. Therefore, the observed reduction of the disease severity in the acs mutants is rather associated with resistance than tolerance. It was also shown that ACS2 and ACS6 were upregulated upon V. dahliae infection in the root and the above ground tissues of the wt plants. Furthermore, the addition of 1-aminocyclopropane-1-carboxylic acid (ACC) and aminooxyacetic acid (AOA), the competitive inhibitor of ACS, in wt A. thaliana, before or after V. dahliae inoculation, revealed that both substances decreased Verticillium wilt symptoms compared to controls irrespectively of the application time. Therefore, our results suggest that the mechanism underpinning the partial resistance of acs2 and acs6 seem to be ethylene depended rather than ACC related, since the application of ACC in the wt led to decreased disease severity compared to control.

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