RESUMO
Vibrio parahaemolyticus is an important foodborne pathogenic bacterium that harbors the type III secretion system 1 (T3SS1) as an essential virulence factor. However, the pathogenesis and infection mechanism mediated by T3SS1 are not entirely clarified. Similar to previous studies on other T3SS-positive bacteria, the T3SS1 needle is a major extracellular component in V. parahaemolyticus. We recently showed that the needle gene-deletion mutant (ΔvscF) exhibited markedly decreased cytotoxicity and effector translocation during interaction with HeLa cells. To further elucidate the pathogenesis of T3SS1 during host cell infection, bacterial RNA was extracted from wild-type POR-1 and ΔvscF mutants under infected condition for comparative RNA sequencing analysis in HeLa cell. The results showed that 120 differentially expressed genes (DEGs) were identified in the ΔvscF-infected group. These encoded proteins of DEGs, such as VP2088, VP2089, and VP2091, were annotated as ABC transporter system, whereas VP0757, VP1123, and VP1289 may be new transcriptional regulators. In addition, the downregulation of T3SS1 had a positive influence on the expression of T3SS2. Moreover, the transcription of the basal body is unaffected by the needle, and there was a close relation among the tip, translocon, and needle, because bacterial adenylate cyclase two-hybrid system (BACTH system) assay indicated the interaction of VP1656, VP1670, VP1693, and VP1694 (VscF). This study provides insights into transcription mechanism of T3SS1 upon infecting HeLa cell, which is expected to better clarify the T3SS1 virulent mechanism.
Assuntos
Vibrioses , Vibrio parahaemolyticus , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Células HeLa , Humanos , Transcriptoma , Vibrioses/microbiologia , Vibrioses/patologia , Vibrio parahaemolyticus/genética , Vibrio parahaemolyticus/metabolismoRESUMO
Vibrio cholerae is a human pathogen, which is transmitted by the consumption of contaminated food or water. V. cholerae strains belonging to the serogroups O1 and O139 can cause cholera outbreaks and epidemics, a severe life-threatening diarrheal disease. In contrast, serogroups other than O1 and O139, denominated as non-O1/non-O139, have been mainly associated with sporadic cases of moderate or mild diarrhea, bacteremia and wound infections. Here we investigated the virulence determinants and phylogenetic origin of a non-O1/non-O139 V. cholerae strain that caused a gastroenteritis outbreak in Santiago, Chile, 2018. We found that this outbreak strain lacks the classical virulence genes harboured by O1 and O139 strains, including the cholera toxin (CT) and the toxin-coregulated pilus (TCP). However, this strain carries genomic islands (GIs) encoding Type III and Type VI secretion systems (T3SS/T6SS) and antibiotic resistance genes. Moreover, we found these GIs are wide distributed among several lineages of non-O1/non-O139 strains. Our results suggest that the acquisition of these GIs may enhance the virulence of non-O1/non-O139 strains that lack the CT and TCP-encoding genes. Our results highlight the pathogenic potential of these V. cholerae strains.
Assuntos
Cólera/microbiologia , Gastroenterite/microbiologia , Genoma Bacteriano , Vibrio cholerae/genética , Criança , Chile , Cólera/epidemiologia , Surtos de Doenças , Farmacorresistência Bacteriana/genética , Gastroenterite/epidemiologia , Ilhas Genômicas , Humanos , Masculino , Filogenia , Vibrio cholerae/patogenicidade , Virulência/genéticaRESUMO
The intimin protein is the major adhesin involved in the intimate adherence of atypical enteropathogenic Escherichia coli (aEPEC) strains to epithelial cells, but little is known about the structures involved in their early colonization process. A previous study demonstrated that the type III secretion system (T3SS) plays an additional role in the adherence of an Escherichia albertii strain. Therefore, we assumed that the T3SS could be related to the adherence efficiency of aEPEC during the first stages of contact with epithelial cells. To test this hypothesis, we examined the adherence of seven aEPEC strains and their eae (intimin) isogenic mutants in the standard HeLa adherence assay and observed that all wild-type strains were adherent while five isogenic eae mutants were not. The two eae mutant strains that remained adherent were then used to generate the eae/escN double mutants (encoding intimin and the T3SS ATPase, respectively) and after the adherence assay, we observed that one strain lost its adherence capacity. This suggested a role for the T3SS in the initial adherence steps of this strain. In addition, we demonstrated that this strain expressed the T3SS at significantly higher levels when compared to the other wild-type strains and that it produced longer translocon-filaments. Our findings reveal that the T3SS-translocon can play an additional role as an adhesin at the beginning of the colonization process of aEPEC.
RESUMO
The intimin protein is the major adhesin involved in the intimate adherence of atypicalenteropathogenicEscherichia coli(aEPEC) strains to epithelial cells, but little is knownabout the structures involved in their early colonization process. A previous studydemonstrated that the type III secretion system (T3SS) plays an additional role in theadherence of anEscherichia albertiistrain. Therefore, we assumed that the T3SS couldbe related to the adherence efficiency of aEPEC during the first stages of contactwith epithelial cells. To test this hypothesis, we examined the adherence of sevenaEPEC strains and theireae(intimin) isogenic mutants in the standard HeLa adherenceassay and observed that all wild-type strains were adherent while five isogeniceaemutants were not. The twoeaemutant strains that remained adherent were then usedto generate theeae/escNdouble mutants (encoding intimin and the T3SS ATPase,respectively) and after the adherence assay, we observed that one strain lost itsadherence capacity. This suggested a role for the T3SS in the initial adherence stepsof this strain. In addition, we demonstrated that this strain expressed the T3SS atsignificantly higher levels when compared to the other wild-type strains and that itproduced longer translocon-filaments. Our findings reveal that the T3SS-transloconcan play an additional role as an adhesin at the beginning of the colonization processof aEPEC.
RESUMO
The cell invasion mechanism of Trypanosoma cruzi has similarities with some intracellular bacterial taxa especially regarding calcium mobilization. This mechanism is not observed in other trypanosomatids, suggesting that the molecules involved in this type of cell invasion were a product of (1) acquisition by horizontal gene transfer (HGT); (2) secondary loss in the other trypanosomatid lineages of the mechanism inherited since the bifurcation Bacteria-Neomura (1.9 billion to 900 million years ago); or (3) de novo evolution from non-homologous proteins via convergent evolution. Similar to T. cruzi, several bacterial genera require increased host cell cytosolic calcium for intracellular invasion. Among intracellular bacteria, the mechanism of host cell invasion of genus Salmonella is the most similar to T. cruzi. The invasion of Salmonella occurs by contact with the host's cell surface and is mediated by the type III secretion system (T3SS) that promotes the contact-dependent translocation of effector proteins directly into host's cell cytoplasm. Here we provide evidence of distant sequence similarities and structurally conserved domains between T. cruzi and Salmonella spp T3SS proteins. Exhaustive database searches were directed to a wide range of intracellular bacteria and trypanosomatids, exploring sequence patterns for comparison of structural similarities and Bayesian phylogenies. Based on our data we hypothesize that T. cruzi acquired genes for calcium mobilization mediated invasion by ancient HGT from ancestral Salmonella lineages.