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[
Appl Environ Microbiol,
2017]
Soil microbes are a major food source for free-living soil nematodes. It is known that certain soil bacteria have evolved systems to combat predation. We identified the nematode-antagonistic Pseudomonas protegens strain 15G2 from screening of microbes. Through protein purification we identified a binary protein, designated as Pp-ANP, that is responsible for the nematicidal activity. This binary protein inhibits Caenorhabditis elegans growth and development by arresting larvae at L1 stage and killing older staged worms. The two subunits, Pp-ANP1a and Pp-ANP2a are active when reconstituted from separate expression in Escherichia coli The binary toxin also shows strong nematicidal activity against three other free-living nematodes, Pristionchus pacificus, Panagrellus redivivus, and Acrobeloides sp., but no activity was found for insects and fungi under test conditions, indicating specificity for nematodes. Pp-ANP1a has no significant homology to any known proteins, while Pp-ANP2a shows 30% homology to E. coli heat-labile enterotoxin (LT) subunit A and cholera toxin (CT) subunit A. Protein modeling indicates Pp-ANP2a is structurally similar to CT/LT and likely acts as a ADP-ribosyltransferase. Despite the similarity, Pp-ANP shows several characteristics distinct from CT/LT toxins. Our results indicate that Pp-ANP is a new enterotoxin-like binary toxin with potent and specific activity to nematodes. The potency and specificity of Pp-ANP suggests applications in controlling parasitic nematodes and opens an avenue for further research on its mechanism of action and role in bacterium-nematode interaction.IMPORTANCE This study reports the discovery of a new enterotoxin-like binary protein, Pp-ANP from a Pseudomonas protegens strain. Pp-ANP shows strong nematicidal activity against Caenorhabditis elegans larvae and older staged worms. It also shows strong activity on other free-living nematodes, Pristionchus pacificus, Panagrellus redivivus, and Acrobeloides sp. The two subunits, Pp-ANP1a and Pp-ANP2a, can be expressed separately and reconstituted to form the active complex when mixed together. Pp-ANP shows some distinct characteristics when compared with other toxins, including Escherichia coli enterotoxin and cholera toxin. The present study indicates that Pp-ANP is a novel binary toxin and that it has potential applications in controlling parasitic nematodes and in studying toxin-host interaction.
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Nishito Y, Masuda S, Sekler I, Nagao M, Hoch E, Fujiwara T, Fu D, Merriman C, Takeda TA, Fukue K, Miyamae Y, Kambe T, Tsuji T, Fukunaka A, Fujimoto S
[
Biochem J,
2016]
Secretory and membrane bound, zinc-requiring enzymes are thought to be activated by binding zinc in the early secretory pathway. One such enzyme, tissue-nonspecific alkaline phosphatase (TNAP), is activated through a two-step mechanism, via protein stabilization and subsequent enzyme activation through metalation, by ZnT5-ZnT6 heterodimers or ZnT7 homodimers. However, little is known about the molecular basis underlying the activation process. Here, we found that the di-proline motif (PP-motif) in luminal loop 2 of ZnT5 and ZnT7 is important for TNAP activation. TNAP activity was significantly reduced in cells lacking ZnT5-ZnT6 heterodimers and ZnT7 homodimers (triple knockout (TKO) cells). The decreased TNAP activity was restored by expressing hZnT5 with hZnT6 or hZnT7, but significantly less so (almost 90% less) by expressing mutants thereof in which the PP-motif was mutated to alanine (PP-AA). In TKO cells, over-expressed hTNAP was not completely activated, and it was converted less efficiently to the holo form by expressing a PP-AA mutant of hZnT5 with hZnT6, whose defects were not restored by zinc supplementation. The zinc transport activity of hZnT7 was not significantly impaired by the PP-AA mutation, indicating that the PP-motif is involved in the TNAP maturation process, although it does not control zinc transport activity. The PP-motif is highly conserved in ZnT5 and ZnT7 orthologs, and its importance for TNAP activation is conserved in the Caenorhabditis elegans hZnT5 ortholog CDF5. These results provide novel molecular insights into the TNAP activation process in the early secretory pathway.
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[
Int Microbiol,
2019]
Considering the emergence of multidrug resistance (MDR) in prevalent human pathogen, Mycobacterium tuberculosis (MTB), there is parallel spurt in development of novel strategies aimed to disrupt MDR. The cell envelope of MTB comprises a wealth of lipid moieties contributing towards long-term survival of pathogen that could be exploited as efficient antitubercular target owing to advancements made in mass spectrometry-based lipidomics technology. This study aimed to utilize the lipidomics approach to unveil several lipid associated changes in response to natural antimycobacterial compound vanillin (Van) in Mycobacterium smegmatis, a surrogate for MTB. Lipidomic analyses revealed that that Van alters the composition of fatty acid (FA), glycerolipid (GL), glycerophospholipid (GP), and saccharolipids (SL). Furthermore, Van leads to potentiation of ampicillin and displayed additive effect. The differential expressions of various lipid biosynthetic pathway genes by RT-PCR corroborated with the lipidomics data. Lastly, we demonstrated enhanced survival of Mycobacterium-infected Caenorhabditis elegans model in presence of Van. Thus, lipidomics approach provided detailed insight into mechanisms of membrane disruption by Van in Mycobacterium smegmatis. Our work offers the basis of further understanding the regulation of lipid homeostasis in MTB so that better therapeutic targets could be identified to combat MDR.
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[
Food Chem,
2020]
Qualitative analysis of bound polyphenols from carrot dietary fiber (CDF-PP) was performed by ultra-performance liquid chromatography equipped with an electrospray ionization and quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS/MS). Eleven organic acids, nine hydroxybenzoic acids and derivatives, six hydroxycinnamic acids and derivatives, four phenolic alcohols and derivatives, three flavonoids and derivatives, seven esters and derivatives, two other compounds, were detected by matching their retention times, secondary mass spectrometry fragment information with authentic standards or literature data. Furthermore, in vitro antioxidant activity was determined by different kinds of assays, including DPPH, ORAC, PSC, demonstrated that CDF-PP could scavenge radicals in a dose dependent manner. Moreover, CDF-PP exhibited significantly reactive oxygen species (ROS) scavenging activity in living Caenorhabditis elegans. To our knowledge, this is the first comprehensive research to investigate composition and in vitro/in vivo antioxidant activity of bound polyphenols in CDF, which implied that CDF-PP could be a promising source of antioxidants.
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[
Mol Cell,
2009]
Three recent papers (Gu et al., 2009; Claycomb et al., 2009; van Wolfswinkel et al., 2009) provide evidence that links a new class of small RNAs and Argonaute-associated complexes to centromere function and genome surveillance.
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[
Curr Med Mycol,
2020]
Background and Purpose: . Materials and Methods: nematode model. Results: infection. The results also confirmed negligible hemolytic activity on erythrocytes. Conclusion: As the findings of the present study indicated, Van is a persuasive natural compound that warrants further attention to exploit its anticandidal potential.
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[
Oikos,
1983]
Life history data, population parameter ("r") and energetics obtained at a wide range of food supply are compared for two species of bacterivorous nematodes. Caenorhabditis briggsae (Cb) is representative for saprobic environments. Plectus palustris (Pp) and related species are known from heterogeneous habitats of higher predictability in food supply but lower bacterial biomass. In Cb the larval phase is short and maximal reproduction is attained immediately after maturation. Pp has a longer prereproductive period and a prolonged phase of egg production rates. Considerably higher rmax and production rates in Cb are linked to greater maintenance costs. Its food threshold is shifted to higher food densities compared to Pp. Differences in the functional response, thresholds and maximal performance of various parameters are contrasted with different qualities of food availability (overall density; heterogeneity; predictability) in the respective habitats of the two species. Short term, unpredictable conditions (i.e. saprobic environments) are expoited by species with high production performances and rmax. The high level of standard metabolism sets constraints at conditions of lower food availability. Heterogeneous environments of higher predictability in food supply call for homeostatic abilities: in Pp this is expressed in lower maintenance requirements, endurance of starvation and a prolonged reproductive phase.
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[
Pharmaceuticals (Basel),
2021]
Macrocyclic lactones (MLs) are widely used drugs to treat and prevent parasitic nematode infections. In many nematode species including a major pathogen of foals, <i>Parascaris univalens</i>, resistance against MLs is widespread, but the underlying resistance mechanisms and ML penetration routes into nematodes remain unknown. Here, we examined how the <i>P</i>-glycoprotein efflux pumps, candidate genes for ML resistance, can modulate drug susceptibility and investigated the role of active drug ingestion for ML susceptibility in the model nematode <i>Caenorhabditis elegans</i>. Wildtype or transgenic worms, modified to overexpress <i>P. univalens</i> PGP-9 (<i>Pun</i>-PGP-9) at the intestine or epidermis, were incubated with ivermectin or moxidectin in the presence (bacteria or serotonin) or absence (no specific stimulus) of pharyngeal pumping (PP). Active drug ingestion by PP was identified as an important factor for ivermectin susceptibility, while moxidectin susceptibility was only moderately affected. Intestinal <i>Pun</i>-PGP-9 expression elicited a protective effect against ivermectin and moxidectin only in the presence of PP stimulation. Conversely, epidermal <i>Pun</i>-PGP-9 expression protected against moxidectin regardless of PP and against ivermectin only in the absence of active drug ingestion. Our results demonstrate the role of active drug ingestion by nematodes for susceptibility and provide functional evidence for the contribution of <i>P</i>-glycoproteins to ML resistance in a tissue-specific manner.
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[
Development,
2023]
Sequential rosettes are a type of collective cell behavior recently discovered in the C. elegans embryo that mediates directional cell migration through sequential formation and resolution of multicellular rosettes involving the migrating cell and its neighboring cells along the way. Here we show that a Planar Cell Polarity (PCP)-based polarity scheme regulates sequential rosettes, which is distinct from the known mode of PCP regulation in multicellular rosettes during the process of convergent extension. Specifically, non-muscle myosin (NMY) localization and edge contraction are perpendicular to that of Van Gogh as opposed to colocalizing with Van Gogh. Further analyses suggest a two-component polarity scheme: one being the canonical PCP pathway with MIG-1/Frizzled and VANG-1/Van Gogh localized to the vertical edges, the other being MIG-1/Frizzled and NMY-2 localized to the midline/contracting edges. The NMY-2 localization and contraction of the midline edges are also required LAT-1/Latrophilin, an adhesion G protein-coupled receptor which has not been shown to regulate multicellular rosettes. Our results establish a distinct mode of PCP-mediated cell intercalation and shed light on the versatile nature of PCP pathway.
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Costa Sidrim JJ, de Alencar LP, Aguiar Cordeiro R, Silva Franco JD, Nogueira Brilhante RS, Serpa R, Souza Collares Maia Castelo-Branco D, Colares de Andrade AR, Leite Mendes PB, de Jesus Evangelista AJ, Carneiro Camara LM, de Oliveira JS, Gadelha Rocha MF, Sales JA
[
Future Microbiol,
2018]
AIM: To investigate the direct effect of antibiotics on growth and virulence of the major Candida species associated with invasive infections. MATERIALS & METHODS: Cefepime, imipenem, meropenem, amoxicillin and vancomycin were tested at twofold the peak plasma concentration (2x PP) and the peak plasma concentration (PP). The effects of antibiotics on Candida albicans, Candida parapsilosis, Candida krusei and Candida tropicalis were investigated by colony counting, flow cytometry, proteolytic activity and virulence in Caenorhabditis elegans. RESULTS: Antibiotics increase growth and proteolytic activity of Candida spp; In addition, amoxicillin potentiates virulence ofC. krusei and C. tropicalis against Caenorhabditis elegans. CONCLUSION: These results suggest that antimicrobial therapy may have a direct effect on the pathophysiology of invasive fungal infections in patients at risk.