<scp>SecReT6</scp>: a web‐based resource for type <scp>VI</scp> secretion systems found in bacteria

Li, Jun; Yao, Yufeng; Xu, H. Howard; Hao, Limin; Deng, Zixin; Rajakumar, Kumar; Ou, Hong‐Yu

doi:10.1111/1462-2920.12794

Cited by 162 publications

(197 citation statements)

References 42 publications

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“…In silico analysis also showed that EHEC had another two vgr genes, vgrG-2 (z0707) and vgrE (z2262) located in the other regions of genome. We then used our integrated database SecReT6 (http://db-mml.sjtu.edu.cn/SecReT6/) to compare the T6SS sequences [25], and found that the components and gene organization of the T6SS gene clusters were highly conserved in pathogenic E . coli strains compared with other bacteria including V .…”

Section: Resultsmentioning

confidence: 99%

Type VI secretion system contributes to Enterohemorrhagic Escherichia coli virulence by secreting catalase against host reactive oxygen species (ROS)

et al. 2017

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Enterohemorrhagic Escherichia coli (EHEC) is one major type of contagious and foodborne pathogens. The type VI secretion system (T6SS) has been shown to be involved in the bacterial pathogenicity and bacteria-bacteria competition. Here, we show that EHEC could secrete a novel effector KatN, a Mn-containing catalase, in a T6SS-dependent manner. Expression of katN is promoted by RpoS and OxyR and repressed by H-NS, and katN contributes to bacterial growth under oxidative stress in vitro. KatN could be secreted into host cell cytosol after EHEC is phagocytized by macrophage, which leads to decreased level of intracellular reactive oxygen species (ROS) and facilitates the intramacrophage survival of EHEC. Finally, animal model results show that the deletion mutant of T6SS was attenuated in virulence compared with the wild type strain, while the deletion mutant of katN had comparable virulence to the wild type strain. Taken together, our findings suggest that EHEC could sense oxidative stress in phagosome and decrease the host cell ROS by secreting catalase KatN to facilitate its survival in the host cells.

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Section: Resultsmentioning

confidence: 99%

Type VI secretion system contributes to Enterohemorrhagic Escherichia coli virulence by secreting catalase against host reactive oxygen species (ROS)

et al. 2017

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“…MAEC ECC-1470 also carries two T6SS determinants located on GI1 (designated as the first ECC-1470 T6SS, T6SS/1) and on GI8 (ECC-1470 T6SS/2), respectively. E. coli ECC-1470 T6SS/1 is classified as subtype i1 [66] or the second E. coli T6SS-2 phylogenetic cluster [67] and T6SS/2 as subtype i2 [66] or the first E. coli T6SS-1 cluster [67]. Subtype i1 T6SSs generally participate in interbacterial competition, subtype i2 T6SSs target eukaryotic cells and play a role in the infection process of pathogens.…”

Section: Discussionmentioning

confidence: 99%

No evidence for a bovine mastitis Escherichia coli pathotype

et al. 2017

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Background Escherichia coli bovine mastitis is a disease of significant economic importance in the dairy industry. Molecular characterization of mastitis-associated E. coli (MAEC) did not result in the identification of common traits. Nevertheless, a mammary pathogenic E. coli (MPEC) pathotype has been proposed suggesting virulence traits that differentiate MAEC from commensal E. coli. The present study was designed to investigate the MPEC pathotype hypothesis by comparing the genomes of MAEC and commensal bovine E. coli.ResultsWe sequenced the genomes of eight E. coli isolated from bovine mastitis cases and six fecal commensal isolates from udder-healthy cows. We analyzed the phylogenetic history of bovine E. coli genomes by supplementing this strain panel with eleven bovine-associated E. coli from public databases. The majority of the isolates originate from phylogroups A and B1, but neither MAEC nor commensal strains could be unambiguously distinguished by phylogenetic lineage. The gene content of both MAEC and commensal strains is highly diverse and dominated by their phylogenetic background. Although individual strains carry some typical E. coli virulence-associated genes, no traits important for pathogenicity could be specifically attributed to MAEC. Instead, both commensal strains and MAEC have very few gene families enriched in either pathotype. Only the aerobactin siderophore gene cluster was enriched in commensal E. coli within our strain panel.ConclusionsThis is the first characterization of a phylogenetically diverse strain panel including several MAEC and commensal isolates. With our comparative genomics approach we could not confirm previous studies that argue for a positive selection of specific traits enabling MAEC to elicit bovine mastitis. Instead, MAEC are facultative and opportunistic pathogens recruited from the highly diverse bovine gastrointestinal microbiota. Virulence-associated genes implicated in mastitis are a by-product of commensalism with the primary function to enhance fitness in the bovine gastrointestinal tract. Therefore, we put the definition of the MPEC pathotype into question and suggest to designate corresponding isolates as MAEC.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-017-3739-x) contains supplementary material, which is available to authorized users.

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“…In addition to the above-mentioned methods specifically for T6SS effector prediction, some online bioinformatics tools or databases provide a suggestion for potential effectors, such as an effector protein predictor, secretEPDB (An et al, 2016, 2017); a T6SS database; SecReT6 (Li et al, 2015); and T346hunter, which can annotate homologs of type III, IV and VI secretion systems automatically (Martínez-García et al, 2015). For researchers working on Burkholderia spp., DBSecSys is an online database for the Burkholderia mallei and Burkholderia pseudomallei secretion system (Memišević et al, 2014, 2016).…”

Section: Past and Current Methods For Identifying T6ss Effectorsmentioning

confidence: 99%

Type VI Secretion Effectors: Methodologies and Biology

Lien

Lai

2017

Front. Cell. Infect. Microbiol.

106

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The type VI secretion system (T6SS) is a nanomachine deployed by many Gram-negative bacteria as a weapon against eukaryotic hosts or prokaryotic competitors. It assembles into a bacteriophage tail-like structure that can transport effector proteins into the environment or target cells for competitive survival or pathogenesis. T6SS effectors have been identified by a variety of approaches, including knowledge/hypothesis-dependent and discovery-driven approaches. Here, we review and discuss the methods that have been used to identify T6SS effectors and the biological and biochemical functions of known effectors. On the basis of the nature and transport mechanisms of T6SS effectors, we further propose potential strategies that may be applicable to identify new T6SS effectors.

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SecReT6: a web‐based resource for type VI secretion systems found in bacteria

Cited by 162 publications

References 42 publications

Type VI secretion system contributes to Enterohemorrhagic Escherichia coli virulence by secreting catalase against host reactive oxygen species (ROS)

Type VI secretion system contributes to Enterohemorrhagic Escherichia coli virulence by secreting catalase against host reactive oxygen species (ROS)

No evidence for a bovine mastitis Escherichia coli pathotype

Type VI Secretion Effectors: Methodologies and Biology

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