Bacillus thuringiensis (Bt) is known for its Cry and Vip3A pesticidal proteins with high selectivity to target pests. Here, we assessed the potential of a novel neotropical Bt strain (UFT038) against six lepidopteran pests, including two Cry-resistant populations of fall armyworm, Spodoptera frugiperda. We also sequenced and analyzed the genome of Bt UFT038 to identify genes involved in insecticidal activities or encoding other virulence factors. In toxicological bioassays, Bt UFT038 killed and inhibited the neonate growth in a concentration-dependent manner. Bt UFT038 and HD-1 were equally toxic against S. cosmioides, S. frugiperda (S_Bt and R_Cry1 + 2Ab populations), Helicoverpa zea, and H. armigera. However, larval growth inhibition results indicated that Bt UFT038 was more toxic than HD-1 to S. cosmioides, while HD-1 was more active against Chrysodeixis includens. The draft genome of Bt UFT038 showed the cry1Aa8, cry1Ac11, cry1Ia44, cry2Aa9, cry2Ab35, and vip3Af5 genes. Besides this, genes encoding the virulence factors (inhA, plcA, piplC, sph, and chi1-2) and toxins (alo, cytK, hlyIII, hblA-D, and nheA-C) were also identified. Collectively, our findings reveal the potential of the Bt UFT038 strain as a source of insecticidal genes against lepidopteran pests, including S. cosmioides and S. frugiperda.
- MeSH
- Bacillus thuringiensis * genetika metabolismus MeSH
- bakteriální proteiny genetika metabolismus MeSH
- biologická kontrola škůdců MeSH
- endotoxiny metabolismus MeSH
- faktory virulence metabolismus MeSH
- Glycine max MeSH
- hemolyziny genetika metabolismus farmakologie MeSH
- insekticidy * farmakologie metabolismus MeSH
- larva MeSH
- lidé MeSH
- můry * MeSH
- novorozenec MeSH
- Spodoptera metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- novorozenec MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The uptake of insecticidal Cry1Ab from genetically engineered (GE) maize, via herbivore Rhopalosiphum padi, to a predator Harmonia axyridis and its potential intergenerational transfer were investigated. Cry1Ab concentration was found to be 400-fold lower in R. padi compared to GE maize, and more than two-fold lower in H. axyridis. For 62% of H. axyridis samples, Cry1Ab was under the limit of detection (LOD), for another 13% were under the limit of quantification (LOQ). The concentration of Cry1Ab was similar between H. axyridis exposed short-term and long-term with the exception of adults after long-term. There was no correlation between Cry1Ab in females and eggs and neonates. The performance of H. axyridis was comparable between Cry1Ab and control. Histological investigation did not show any pathological changes in the digestive and reproductive systems. The detected route of exposure is unlikely to be important for functional biological control by H. axyridis in agroecosystem.
- MeSH
- bakteriální proteiny genetika metabolismus MeSH
- brouci * metabolismus MeSH
- endotoxiny * MeSH
- geneticky modifikované rostliny metabolismus MeSH
- hemolyziny genetika metabolismus MeSH
- kukuřice setá genetika metabolismus MeSH
- larva metabolismus MeSH
- lidé MeSH
- novorozenec MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- novorozenec MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Mitochondrial substrate flux is a distinguishing characteristic of each cell type, and changes in its components such as transporters, channels, or enzymes are involved in the pathogenesis of several diseases. Mitochondrial substrate flux can be studied using intact cells, permeabilized cells, or isolated mitochondria. Investigating intact cells encounters several problems due to simultaneous oxidation of different substrates. Besides, several cell types contain internal stores of different substrates that complicate results interpretation. Methods such as mitochondrial isolation or using permeabilizing agents are not easily reproducible. Isolating pure mitochondria with intact membranes in sufficient amounts from small samples is problematic. Using non-selective permeabilizers causes various degrees of unavoidable mitochondrial membrane damage. Recombinant perfringolysin O (rPFO) was offered as a more appropriate permeabilizer, thanks to its ability to selectively permeabilize plasma membrane without affecting mitochondrial integrity. When used in combination with microplate respirometry, it allows testing the flux of several mitochondrial substrates with enough replicates within one experiment while using a minimal number of cells. In this work, the protocol describes a method to compare mitochondrial substrate flux of two different cellular phenotypes or genotypes and can be customized to test various mitochondrial substrates or inhibitors.
In a wide range of organisms, from bacteria to humans, numerous proteins have to be posttranslationally acylated to become biologically active. Bacterial repeats in toxin (RTX) cytolysins form a prominent group of proteins that are synthesized as inactive protoxins and undergo posttranslational acylation on ε-amino groups of two internal conserved lysine residues by co-expressed toxin-activating acyltransferases. Here, we investigated how the chemical nature, position, and number of bound acyl chains govern the activities of Bordetella pertussis adenylate cyclase toxin (CyaA), Escherichia coli α-hemolysin (HlyA), and Kingella kingae cytotoxin (RtxA). We found that the three protoxins are acylated in the same E. coli cell background by each of the CyaC, HlyC, and RtxC acyltransferases. We also noted that the acyltransferase selects from the bacterial pool of acyl-acyl carrier proteins (ACPs) an acyl chain of a specific length for covalent linkage to the protoxin. The acyltransferase also selects whether both or only one of two conserved lysine residues of the protoxin will be posttranslationally acylated. Functional assays revealed that RtxA has to be modified by 14-carbon fatty acyl chains to be biologically active, that HlyA remains active also when modified by 16-carbon acyl chains, and that CyaA is activated exclusively by 16-carbon acyl chains. These results suggest that the RTX toxin molecules are structurally adapted to the length of the acyl chains used for modification of their acylated lysine residue in the second, more conserved acylation site.
- MeSH
- acyltransferasy metabolismus MeSH
- Bacteria metabolismus MeSH
- bakteriální proteiny metabolismus MeSH
- buněčné linie MeSH
- hemolyziny metabolismus MeSH
- mastné kyseliny metabolismus MeSH
- myši MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Understanding indirect, trophic-level effects of genetically engineered plants, expressing insecticidal proteins derived from the bacterium, Bacillus thuringiensis (Bt), is essential to the ecological risk assessment process. In this study, we examine potential indirect, trophic-level effects of Bt-sensitive prey using the predator, Harmonia axyridis (Pallas), feeding upon Spodoptera frugiperda (J.E. Smith) larvae, which had delayed development (lower body mass) following ingestion of Cry1Ab maize leaves. We found no adverse effects on development and survival when H. axyridis larvae were fed S. frugiperda larvae that had fed on Cry1Ab maize tissue. Presence of Cry1Ab in H. axyridis decreased considerably after switching to another diet within 48 h. In a no-choice assay, H. axyridis larvae consumed more Bt-fed S. frugiperda than non-Bt-fed larvae. Preference for S. frugiperda feeding on Bt maize was confirmed in subsequent choice assays with H. axyridis predation on Bt-fed, 1-5-d-old S. frugiperda larvae. We suggest that H. axyridis preferred prey, not based on whether it had fed on Bt or non-Bt maize, but rather on larval mass, and they compensated for the nutritional deficiency of lighter larvae through increased consumption. Pest larvae with variable levels of resistance developing on Bt diet are often stunted versus sensitive larvae developing on non-Bt diet. It is possible that such larvae may be preferentially removed from local field populations. These results may have implications for insect resistance management and may be played out under field conditions where seed blends of Bt and non-Bt hybrids are planted.
- MeSH
- Bacillus thuringiensis klasifikace MeSH
- bakteriální proteiny metabolismus MeSH
- biologická kontrola škůdců * MeSH
- brouci růst a vývoj fyziologie MeSH
- endotoxiny metabolismus MeSH
- geneticky modifikované rostliny genetika růst a vývoj fyziologie MeSH
- hemolyziny metabolismus MeSH
- kukuřice setá genetika růst a vývoj fyziologie MeSH
- larva růst a vývoj mikrobiologie fyziologie MeSH
- potravní řetězec * MeSH
- predátorské chování * MeSH
- Spodoptera růst a vývoj mikrobiologie fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The adenylate cyclase toxin-hemolysin (CyaA, ACT, or AC-Hly) of Bordetella pertussis targets phagocytic cells expressing the complement receptor 3 (CR3, Mac-1, αMβ2 integrin, or CD11b/CD18). CyaA delivers into cells an N-terminal adenylyl cyclase (AC) enzyme domain that is activated by cytosolic calmodulin and catalyzes unregulated conversion of cellular ATP into cyclic AMP (cAMP), a key second messenger subverting bactericidal activities of phagocytes. In parallel, the hemolysin (Hly) moiety of CyaA forms cation-selective hemolytic pores that permeabilize target cell membranes. We constructed the first B. pertussis mutant secreting a CyaA toxin having an intact capacity to deliver the AC enzyme into CD11b-expressing (CD11b(+)) host phagocytes but impaired in formation of cell-permeabilizing pores and defective in cAMP elevation in CD11b(-) cells. The nonhemolytic AC(+) Hly(-) bacteria inhibited the antigen-presenting capacities of coincubated mouse dendritic cells in vitro and skewed their Toll-like receptor (TLR)-triggered maturation toward a tolerogenic phenotype. The AC(+) Hly(-) mutant also infected mouse lungs as efficiently as the parental AC(+) Hly(+) strain. Hence, elevation of cAMP in CD11b(-) cells and/or the pore-forming capacity of CyaA were not required for infection of mouse airways. The latter activities were, however, involved in bacterial penetration across the epithelial layer, enhanced neutrophil influx into lung parenchyma during sublethal infections, and the exacerbated lung pathology and lethality of B. pertussis infections at higher inoculation doses (>10(7) CFU/mouse). The pore-forming activity of CyaA further synergized with the cAMP-elevating activity in downregulation of major histocompatibility complex class II (MHC-II) molecules on infiltrating myeloid cells, likely contributing to immune subversion of host defenses by the whooping cough agent.
- MeSH
- adenylátcyklasový toxin metabolismus MeSH
- AMP cyklický metabolismus MeSH
- antigeny CD11b metabolismus MeSH
- Bordetella pertussis patogenita MeSH
- buněčná membrána metabolismus MeSH
- dendritické buňky imunologie MeSH
- fagocyty imunologie MeSH
- hemolyziny metabolismus MeSH
- makrofágový antigen 1 metabolismus MeSH
- myši inbrední BALB C MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- pertuse mikrobiologie MeSH
- plíce mikrobiologie patologie MeSH
- T-lymfocyty imunologie MeSH
- virulence MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
A large subgroup of the repeat in toxin (RTX) family of leukotoxins of Gram-negative pathogens consists of pore-forming hemolysins. These can permeabilize mammalian erythrocytes (RBCs) and provoke their colloid osmotic lysis (hemolytic activity). Recently, ATP leakage through pannexin channels and P2X receptor-mediated opening of cellular calcium and potassium channels were implicated in cell permeabilization by pore-forming toxins. In the study described here, we examined the role played by purinergic signaling in the cytolytic action of two RTX toxins that form pores of different sizes. The cytolytic potency of ApxIA hemolysin of Actinobacillus pleuropneumoniae, which forms pores about 2.4 nm wide, was clearly reduced in the presence of P2X7 receptor antagonists or an ATP scavenger, such as pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), Brilliant Blue G, ATP oxidized sodium salt, or hexokinase. In contrast, antagonists of purinergic signaling had no impact on the hemolytic potency of the adenylate cyclase toxin-hemolysin (CyaA) of Bordetella pertussis, which forms pores of 0.6 to 0.8 nm in diameter. Moreover, the conductance of pores formed by ApxIA increased with the toxin concentration, while the conductance of the CyaA single pore units was constant at various toxin concentrations. However, the P2X7 receptor antagonist PPADS inhibited in a concentration-dependent manner the exacerbated hemolytic activity of a CyaA-ΔN489 construct (lacking 489 N-terminal residues of CyaA), which exhibited a strongly enhanced pore-forming propensity (>20-fold) and also formed severalfold larger conductance units in planar lipid bilayers than intact CyaA. These results point to a pore size threshold of purinergic amplification involvement in cell permeabilization by pore-forming RTX toxins.
- MeSH
- Actinobacillus pleuropneumoniae metabolismus MeSH
- adenylátcyklasový toxin antagonisté a inhibitory chemie metabolismus MeSH
- bakteriální proteiny antagonisté a inhibitory chemie metabolismus MeSH
- Bordetella pertussis metabolismus MeSH
- buněčná membrána metabolismus MeSH
- erytrocyty metabolismus MeSH
- hemolýza * MeSH
- hemolyziny antagonisté a inhibitory chemie metabolismus MeSH
- hexokinasa MeSH
- kultivované buňky MeSH
- lipidové dvojvrstvy metabolismus MeSH
- makrofágy MeSH
- myši MeSH
- osmotický tlak MeSH
- permeabilita buněčné membrány MeSH
- pyridoxalfosfát analogy a deriváty MeSH
- rosanilinová barviva MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This study clarifies the membrane disruption mechanisms of two bacterial RTX toxins: alphahemolysin (HlyA) from Escherichia coli and a highly homologous adenylate cyclase toxin (CyaA) from Bordetella pertussis. For this purpose, we employed a fluorescence requenching method using liposomes (extruded through filters of different pore size - 1000 nm, 400 nm or 100 nm) with encapsulated fluorescent dye/quencher pair ANTS/DPX. We showed that both toxins induced a graded leakage of liposome content with different selectivities alpha for DPX and ANTS. In contrast to HlyA, CyaA exhibited a higher selectivity for cationic quencher DPX, which increased with vesicle diameter. Large unilamellar vesicles (LUV(1000)) were found to be more suitable for distinguishing between high alpha values whereas smaller ones (LUV(100)) were more appropriate for discriminating an all-or-none leakage (alpha=0) from the graded leakage with low values of alpha. While disrupting LUV(1000), CyaA caused a highly cation-selective leakage (alpha~15) whereas its mutated form with decreased channel K(+)/Cl(-) selectivity due to two substitutions in a predicted transmembrane segment (CyaA-E509K+E516K) exhibited much lower selectivity (alpha approximately 6). We concluded that the fluorescence requenching method in combination with different size of liposomes is a valuable tool for characterization of pore-forming toxins and their variants.
- MeSH
- adenylátcyklasový toxin metabolismus MeSH
- Bordetella pertussis fyziologie MeSH
- buněčná membrána fyziologie MeSH
- elektroforéza v agarovém gelu MeSH
- Escherichia coli fyziologie MeSH
- fluorescenční spektrometrie MeSH
- hemolyziny metabolismus MeSH
- kinetika MeSH
- liposomy metabolismus MeSH
- permeabilita buněčné membrány fyziologie MeSH
- proteiny z Escherichia coli metabolismus MeSH
- Publikační typ
- práce podpořená grantem MeSH
A total 355 of Staphylococcus cohnii isolates from hospital environment, patients (newborns), medical staff and from non-hospital environment were tested for hemolytic activity. Ninety-one % of S. cohnii ssp. cohnii and 74.5 % S. cohnii ssp. urealyticus strains exhibited hemolysis synergistic to S. aureus ATCC 25923 strain. Crude preparations of hemolysins of both bacterial subspecies presented delta-hemolysin, but not alpha- and beta-toxin activity. Highly pure hemolysins were obtained by semipreparative SDS-PAGE or by organic solvent extraction from the freeze-dried crude preparations. Native-PAGE and 2D-PAGE showed their high heterogeneity. Molar masses of single hemolysin units estimated by the Tris-Tricine-SDS-PAGE were calculated as 3.47 kDa for S. cohnii ssp. cohnii and 3.53 kDa for S. cohnii ssp. urealyticus.
- MeSH
- dospělí MeSH
- elektroforéza v polyakrylamidovém gelu MeSH
- hemolyziny izolace a purifikace metabolismus MeSH
- infekce spojené se zdravotní péčí mikrobiologie MeSH
- isoelektrická fokusace MeSH
- kůže mikrobiologie MeSH
- lidé MeSH
- molekulová hmotnost MeSH
- novorozenec MeSH
- personál nemocniční MeSH
- stafylokokové infekce mikrobiologie MeSH
- Staphylococcus chemie izolace a purifikace MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- novorozenec MeSH
- Geografické názvy
- Polsko MeSH
- Klíčová slova
- C-fragment, hlyA- mutant, hemolytický kmen, experimentální kolonizace,
- MeSH
- alergologie a imunologie MeSH
- antibakteriální látky MeSH
- antigeny * MeSH
- aplikace orální MeSH
- Clostridium tetani MeSH
- DNA bakterií MeSH
- Escherichia coli * MeSH
- feces mikrobiologie MeSH
- hemolyziny metabolismus MeSH
- imunitní systém - jevy MeSH
- imunizace * metody MeSH
- imunologické testy MeSH
- kultivační techniky MeSH
- lidé MeSH
- mikrobiologie * MeSH
- myši inbrední BALB C MeSH
- novorozenec MeSH
- plazmidy MeSH
- prasata MeSH
- střeva MeSH
- tetanový toxin MeSH
- tetanus * MeSH
- vakcíny MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- novorozenec MeSH
- zvířata MeSH
