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Current Biology : CB Jun 2024The bacterial type VI secretion system (T6SS) is a widespread, kin-discriminatory weapon capable of shaping microbial communities. Due to the system's dependency on...
The bacterial type VI secretion system (T6SS) is a widespread, kin-discriminatory weapon capable of shaping microbial communities. Due to the system's dependency on contact, cellular interactions can lead to either competition or kin protection. Cell-to-cell contact is often accomplished via surface-exposed type IV pili (T4Ps). In Vibrio cholerae, these T4Ps facilitate specific interactions when the bacteria colonize natural chitinous surfaces. However, it has remained unclear whether and, if so, how these interactions affect the bacterium's T6SS-mediated killing. In this study, we demonstrate that pilus-mediated interactions can be harnessed by T6SS-equipped V. cholerae to kill non-kin cells under liquid growth conditions. We also show that the naturally occurring diversity of pili determines the likelihood of cell-to-cell contact and, consequently, the extent of T6SS-mediated competition. To determine the factors that enable or hinder the T6SS's targeted reduction of competitors carrying pili, we developed a physics-grounded computational model for autoaggregation. Collectively, our research demonstrates that T4Ps involved in cell-to-cell contact can impose a selective burden when V. cholerae encounters non-kin cells that possess an active T6SS. Additionally, our study underscores the significance of T4P diversity in protecting closely related individuals from T6SS attacks through autoaggregation and spatial segregation.
Topics: Vibrio cholerae; Type VI Secretion Systems; Fimbriae, Bacterial; Microbial Interactions
PubMed: 38749426
DOI: 10.1016/j.cub.2024.04.041 -
International Journal of Food... Jun 2024Prevalent in marine, estuarine and coastal environments, Vibrio parahaemolyticus is one of the major foodborne pathogens which can cause acute gastroenteritis through...
Prevalent in marine, estuarine and coastal environments, Vibrio parahaemolyticus is one of the major foodborne pathogens which can cause acute gastroenteritis through consumption of contaminated food. This study encompassed antimicrobial resistance, molecular characteristics and phylogenetic relationships of 163 V. parahaemolyticus isolated from aquatic foods across 15 provinces in China. The isolates showed high resistance rates against ampicillin (90.80 %, 148/163) and cefazolin (72.39 %, 118/163). Only 5 isolates demonstrated multi-drug resistance (MDR) phenotypes. A total of 37 different antibiotic resistance genes (ARGs) in correlation with seven antimicrobial categories were identified. tet(34) and tet(35) were present in all 163 isolates. Other most prevalent ARGs were those conferring resistance to β-lactams, with prevalence rate around 18.40 % (30/163). The virulence genes tdh and trh were found in 17 (10.43 %) and 9 (5.52 %) isolates, respectively. Totally 121 sequence types (STs) were identified through whole genome analysis, among which 60 were novel. The most prevalent sequence type was ST3 (9.20 %, 15/163), which shared the same genotype profile of trh, tdh and bla. Most of the tdhV. parahaemolyticus isolates was clustered into a distinctive clade by the phylogenetic analysis. Our study showed that the antimicrobial resistance of V. parahaemolyticus in aquatic foods in China was moderate. However, the emerging of MDR isolates implicate strengthened monitoring is needed for the better treatment of human V. parahaemolyticus infections. High genetic diversity and virulence potential of the isolates analyzed in this study help better understanding and evaluating the risk of V. parahaemolyticus posed to public health.
Topics: Vibrio parahaemolyticus; China; Phylogeny; Anti-Bacterial Agents; Microbial Sensitivity Tests; Food Microbiology; Seafood; Drug Resistance, Multiple, Bacterial; Genome, Bacterial; Virulence Factors; Humans; Genotype
PubMed: 38749264
DOI: 10.1016/j.ijfoodmicro.2024.110737 -
Frontiers in Immunology 2024The California purple sea urchin, , relies solely on an innate immune system to combat the many pathogens in the marine environment. One aspect of their molecular...
INTRODUCTION
The California purple sea urchin, , relies solely on an innate immune system to combat the many pathogens in the marine environment. One aspect of their molecular defenses is the () gene family that is upregulated in response to immune challenge. The gene sequences are highly variable both within and among animals and likely encode thousands of SpTrf isoforms within the sea urchin population. The native SpTrf proteins bind foreign targets and augment phagocytosis of a marine . A recombinant (r)SpTrf-E1-Ec protein produced by also binds but does not augment phagocytosis.
METHODS
To address the question of whether other rSpTrf isoforms function as opsonins and augment phagocytosis, six rSpTrf proteins were expressed in insect cells.
RESULTS
The rSpTrf proteins are larger than expected, are glycosylated, and one dimerized irreversibly. Each rSpTrf protein cross-linked to inert magnetic beads (rSpTrf::beads) results in different levels of surface binding and phagocytosis by phagocytes. Initial analysis shows that significantly more rSpTrf::beads associate with cells compared to control BSA::beads. Binding specificity was verified by pre-incubating the rSpTrf::beads with antibodies, which reduces the association with phagocytes. The different rSpTrf::beads show significant differences for cell surface binding and phagocytosis by phagocytes. Furthermore, there are differences among the three distinct types of phagocytes that show specific vs. constitutive binding and phagocytosis.
CONCLUSION
These findings illustrate the complexity and effectiveness of the sea urchin innate immune system driven by the natSpTrf proteins and the phagocyte cell populations that act to neutralize a wide range of foreign pathogens.
Topics: Animals; Phagocytosis; Phagocytes; Recombinant Proteins; Protein Binding; Strongylocentrotus purpuratus; Immunity, Innate; Protein Isoforms; Sea Urchins; Vibrio; Opsonin Proteins
PubMed: 38742116
DOI: 10.3389/fimmu.2024.1372904 -
International Microbiology : the... May 2024The gills and skin microbiota and microbiome of wild fish remain far more under-investigated compared to that of farmed fish species, despite that these animal-microbe...
The gills and skin microbiota and microbiome of wild fish remain far more under-investigated compared to that of farmed fish species, despite that these animal-microbe interactions hold the same ecophysiological roles in both cases. In this study, the gills and skin bacterial microbiota profiles and their presumptive bacterial metabolisms were investigated in five open-sea fishes: bullet tuna (Auxis sp.), common dolphinfish (Coryphaena hippurus), Atlantic little tunny (Euthynnus alletteratus), Atlantic bonito (Sarda sarda) and Atlantic white marlin (Kajikia albida). Gills and skin tissues were collected from two to three individuals per species, from specimens caught by recreational trolling during summer of 2019, and their bacterial 16S rRNA gene diversity was analysed by high-throughput sequencing. The gills bacterial communities among the five species were clearly different but not the skin bacterial microbiota. The dominant operational taxonomic units belonged to the Moraxellaceae, Pseudomonadaceae, Rhodobacteraceae, Staphylococcaceae and Vibrionaceae families. Despite the differences in taxonomic composition, the presumptive bacterial metabolisms between the gills and skin of the five fishes investigated here were ≥ 94% similar and were dominated by basic metabolism, most likely reflecting the continuous exposure of these tissues in the surrounding seawater.
PubMed: 38740652
DOI: 10.1007/s10123-024-00524-8 -
Nature Jun 2024Although eukaryotic Argonautes have a pivotal role in post-transcriptional gene regulation through nucleic acid cleavage, some short prokaryotic Argonaute variants...
Although eukaryotic Argonautes have a pivotal role in post-transcriptional gene regulation through nucleic acid cleavage, some short prokaryotic Argonaute variants (pAgos) rely on auxiliary nuclease factors for efficient foreign DNA degradation. Here we reveal the activation pathway of the DNA defence module DdmDE system, which rapidly eliminates small, multicopy plasmids from the Vibrio cholerae seventh pandemic strain (7PET). Through a combination of cryo-electron microscopy, biochemistry and in vivo plasmid clearance assays, we demonstrate that DdmE is a catalytically inactive, DNA-guided, DNA-targeting pAgo with a distinctive insertion domain. We observe that the helicase-nuclease DdmD transitions from an autoinhibited, dimeric complex to a monomeric state upon loading of single-stranded DNA targets. Furthermore, the complete structure of the DdmDE-guide-target handover complex provides a comprehensive view into how DNA recognition triggers processive plasmid destruction. Our work establishes a mechanistic foundation for how pAgos utilize ancillary factors to achieve plasmid clearance, and provides insights into anti-plasmid immunity in bacteria.
Topics: Argonaute Proteins; Bacterial Proteins; Cryoelectron Microscopy; Deoxyribonucleases; DNA Helicases; DNA, Single-Stranded; Models, Molecular; Plasmids; Protein Domains; Protein Multimerization; Vibrio cholerae
PubMed: 38740055
DOI: 10.1038/s41586-024-07515-9 -
The Journal of Medical Investigation :... 2024Vibrio vulnificus (V. vulnificus) is a halophilic gram-negative bacterium that inhabits coastal warm water and induce severe diseases such as primary septicemia. To...
Vibrio vulnificus (V. vulnificus) is a halophilic gram-negative bacterium that inhabits coastal warm water and induce severe diseases such as primary septicemia. To investigate the mechanisms of rapid bacterial translocation on intestinal infection, we focused on outer membrane vesicles (OMVs), which are extracellular vesicles produced by Gram-negative bacteria and deliver virulence factors. However, there are very few studies on the pathogenicity or contents of V. vulnificus OMVs (Vv-OMVs). In this study, we investigated the effects of Vv-OMVs on host cells. Epithelial cells INT407 were stimulated with purified OMVs and morphological alterations and levels of lactate dehydrogenase (LDH) release were observed. In cells treated with OMVs, cell detachment without LDH release was observed, which exhibited different characteristics from cytotoxic cell detachment observed in V. vulnificus infection. Interestingly, OMVs from a Vibrio Vulnificus Hemolysin (VVH) and Multifunctional-autoprocessing repeats-in -toxin (MARTX) double-deletion mutant strain also caused cell detachment without LDH release. Our results suggested that the proteolytic function of a serine protease contained in Vv-OMVs may contribute to pathogenicity of V. vulnificus by assisting bacterial translocation. This study reveals a new pathogenic mechanism during V. vulnificus infections. J. Med. Invest. 71 : 102-112, February, 2024.
Topics: Vibrio vulnificus; Humans; Extracellular Vesicles; Hemolysin Proteins; L-Lactate Dehydrogenase; Bacterial Outer Membrane; Epithelial Cells
PubMed: 38735705
DOI: 10.2152/jmi.71.102 -
Indian Journal of Medical Microbiology 2024Non-O1/non-O139 Vibrio cholerae, a comparably poorly studied pathogen is culpable of sporadic but serious infections. We report a case of non O1 non O139 Vibrio cholerae... (Review)
Review
Non-O1/non-O139 Vibrio cholerae, a comparably poorly studied pathogen is culpable of sporadic but serious infections. We report a case of non O1 non O139 Vibrio cholerae septicemia in a middle aged male recently diagnosed with carcinoma pancreas. He underwent biliary tract interventional procedure for hematemesis three weeks before the presentation. Now, he presented with fever, abdominal pain, hematemesis and melena. Endoscopy revealed severe portal hypertensive gastropathy and mild hemobilia. Blood culture grew Vibrio cholerae, identified as non O1 non O139 by serogrouping. He recovered successfully with timely diagnosis, appropriate antibiotics and supportive measures.
Topics: Humans; Male; Pancreatic Neoplasms; Vibrio cholerae non-O1; Sepsis; Middle Aged; Anti-Bacterial Agents; Cholera; Vibrio Infections
PubMed: 38735644
DOI: 10.1016/j.ijmmb.2024.100611 -
Microbiological Research Aug 2024Vibrio parahaemolyticus is the leading bacterial cause of gastroenteritis associated with seafood consumption worldwide. Not all members of the species are thought to be...
Vibrio parahaemolyticus is the leading bacterial cause of gastroenteritis associated with seafood consumption worldwide. Not all members of the species are thought to be pathogenic, thus identification of virulent organisms is essential to protect public health and the seafood industry. Correlations of human disease and known genetic markers (e.g. thermostable direct hemolysin (TDH), TDH-related hemolysin (TRH)) appear complex. Some isolates recovered from patients lack these factors, while their presence has become increasingly noted in isolates recovered from the environment. Here, we used whole-genome sequencing in combination with mammalian and insect models of infection to assess the pathogenic potential of V. parahaemolyticus isolated from European Atlantic shellfish production areas. We found environmental V. parahaemolyticus isolates harboured multiple virulence-associated genes, including TDH and/or TRH. However, carriage of these factors did not necessarily reflect virulence in the mammalian intestine, as an isolate containing TDH and the genes coding for a type 3 secretion system (T3SS) 2α virulence determinant, appeared avirulent. Moreover, environmental V. parahaemolyticus lacking TDH or TRH could be assigned to groups causing low and high levels of mortality in insect larvae, with experiments using defined bacterial mutants showing that a functional T3SS1 contributed to larval death. When taken together, our findings highlight the genetic diversity of V. parahaemolyticus isolates found in the environment, their potential to cause disease and the need for a more systematic evaluation of virulence in diverse V. parahaemolyticus to allow better genetic markers.
Topics: Vibrio parahaemolyticus; Animals; Virulence; Europe; Hemolysin Proteins; Virulence Factors; Vibrio Infections; Bacterial Proteins; Bacterial Toxins; Humans; Whole Genome Sequencing; Phenotype; Shellfish; Larva; Type III Secretion Systems; Genome, Bacterial; Seafood
PubMed: 38735242
DOI: 10.1016/j.micres.2024.127744 -
Carbohydrate Research Jun 2024Chitooligosaccharides, the hydrolysis products of chitin, have superior biological activities and application value to those of chitin itself; however, the ordered and...
Chitooligosaccharides, the hydrolysis products of chitin, have superior biological activities and application value to those of chitin itself; however, the ordered and highly crystalline structure of chitin renders its degradation by chitinase difficult. Herein, the effects of plasma-activated water (PAW) pre-treatment on the physicochemical properties, crystal structure, and enzymatic hydrolysis of chitin were investigated. The hydrolysis of PAW-pre-treated chitin (PAW activation time of 5 min) using chitinase from Vibrio harveyi (VhChit2) yielded 71 % more reducing sugar, compared with that from untreated chitin, with the degree of chitin hydrolysis increasing from 13 % without pre-treatment to 23 % post-treatment. Moreover, the amount of VhChit2 adsorbed by chitin increased from 41.7 to 58.2 mg/g. Fourier transform infrared spectrometry revealed that PAW could break the β-1,4-glycosidic bonds of chitin (but had no effects on the hydrogen and amido bonds), thereby decreasing the molecular weight and crystallinity of the polysaccharide, which caused its structural damage and enhanced its enzymatic hydrolysis by chitinase. Consequently, PAW pre-treatment can be considered a simple, effective, and environmentally-friendly method for the biotransformation of chitin as its easier hydrolysis yields high-value products.
Topics: Chitinases; Chitin; Water; Hydrolysis; Molecular Weight; Vibrio
PubMed: 38733729
DOI: 10.1016/j.carres.2024.109144 -
International Journal of Biological... Jun 2024Vascular endothelial growth factor (VEGF) and VEGF reporter (VEGFR) are essential molecules in VEGF signalling pathway. Although the functions of VEGF and VEGFR have...
Vascular endothelial growth factor (VEGF) and VEGF reporter (VEGFR) are essential molecules in VEGF signalling pathway. Although the functions of VEGF and VEGFR have been well reported in vertebrates, their functions are still poorly understood in invertebrates. In this study, the open reading frame sequences of EsVEGF1 and EsVEGFR4 were cloned from Eriocheir sinensis, and their corresponding proteins shared typical structure characteristics with their counterparts in other species. EsVEGF1 were predominantly expressed in hepatopancreas and muscle while EsVEGFR4 mainly expressed in hemocytes and intestine. The expression levels of EsVEGF1 in hemocytes were rapidly induced by Staphylococcus aureus and Vibrio parahaemolyticus, and it also increased rapidly in hepatopancreas after being challenged with V. parahaemolyticus. The expression levels of EsVEGFR4 only increased in hepatopancreas of crabs injected with S. aureus. The extracellular immunoglobulin domain of EsVEGFR4 could bind with Gram-negative and Gram-positive bacteria as well as lipopolysaccharide and peptidoglycan. EsVEGF1 could act as the ligand for EsVEGFR4 and Toll-like receptor and regulate the expression of crustins and lysozyme with a tissue-specific manner, while have no regulatory function on that of anti-lipopolysaccharide factors. This study will provide new insights into the immune defense mechanisms mediated by VEGF and VEGFR in crustaceans.
Topics: Animals; Brachyura; Vascular Endothelial Growth Factor A; Receptors, Vascular Endothelial Growth Factor; Antimicrobial Peptides; Amino Acid Sequence; Staphylococcus aureus; Gene Expression Regulation; Vibrio parahaemolyticus; Phylogeny; Hepatopancreas; Hemocytes
PubMed: 38729487
DOI: 10.1016/j.ijbiomac.2024.132242