scholarly journals T6SS Mediated Stress Responses for Bacterial Environmental Survival and Host Adaptation

2021 ◽  
Vol 22 (2) ◽  
pp. 478
Author(s):  
Kai-Wei Yu ◽  
Peng Xue ◽  
Yang Fu ◽  
Liang Yang
Keyword(s):  
Protein Secretion ◽  
Stress Responses ◽  
Current Knowledge ◽  
Bacterial Species ◽  
Host Cells ◽  
Interspecies Interactions ◽  
Type Vi Secretion System ◽  
Membrane Complex ◽  
Type Vi Secretion ◽  
Bacterial Type

The bacterial type VI secretion system (T6SS) is a protein secretion apparatus widely distributed in Gram-negative bacterial species. Many bacterial pathogens employ T6SS to compete with the host and to coordinate the invasion process. The T6SS apparatus consists of a membrane complex and an inner tail tube-like structure that is surrounded by a contractile sheath and capped with a spike complex. A series of antibacterial or antieukaryotic effectors is delivered by the puncturing device consisting of a Hcp tube decorated by the VgrG/PAAR complex into the target following the contraction of the TssB/C sheath, which often leads to damage and death of the competitor and/or host cells. As a tool for protein secretion and interspecies interactions, T6SS can be triggered by many different mechanisms to respond to various physiological conditions. This review summarizes our current knowledge of T6SS in coordinating bacterial stress responses against the unfavorable environmental and host conditions.

scholarly journals Population dynamics and transcriptomic responses ofPseudomonas aeruginosain a complex laboratory microbial community

2018 ◽  
Author(s):  
Yingying Cheng ◽  
Joey Kuok Hoong Yam ◽  
Zhao Cai ◽  
Yichen Ding ◽  
Lian-Hui Zhang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Single Molecule ◽  
Dominant Species ◽  
Bacterial Species ◽  
Secretion System ◽  
Interspecies Interactions ◽  
Type Vi Secretion System ◽  
Mixed Species ◽  
Type Vi Secretion ◽  
Biofilm Community

AbstractPseudomonas aeruginosais one of the dominant species when it co-exists with many other bacterial species in diverse environments. To understand its physiology and interactions with co-existing bacterial species in different conditions, we established physiologically reproducible eighteen-species communities, and found thatP. aeruginosabecame the dominant species in mixed-species biofilm community but not in the planktonic community.P. aeruginosaH1 type VI secretion system was highly induced in the mixed-species biofilm community compare to its mono-species biofilm, which was further demonstrated to play a key role forP. aeruginosato gain fitness over other bacterial species. In addition, the type IV pili and Psl exopolysaccharide were shown to be required forP. aeruginosato compete with other bacterial species in the biofilm community. Our study showed that the physiology ofP. aeruginosais strongly affected by interspecies interactions, and both biofilm determinants and H1 type VI secretion system contribute toP. aeruginosafitness over other species in complex biofilm communities.ImportancePseudomonas aeruginosausually coexists with different bacterial species in natural environment. However, systematic comparative characterization ofP. aeruginosain complex microbial communities with its mono-species communities is lacking. We constructed mixed-species planktonic and biofilm communities consistingP. aeruginosaand seventeen other bacterial species to study the physiology and interaction ofP. aeruginosain complex multiple-species community. A single molecule detection platform, NanoString nCounter®16S rRNA array, was used to shown thatP. aeruginosacan become the dominant species in the biofilm communities while not in the planktonic communities. Comparative transcriptomic analysis and fluorescence-based quantification further revealed thatP. aeruginosaH1 type VI secretion system and biofilm determinants are both required for its fitness in mixed-species biofilm communities.

scholarly journals In situ and high‐resolution cryo‐ EM structure of a bacterial type VI secretion system membrane complex

2019 ◽  
Vol 38 (10) ◽  
Author(s):  
Chiara Rapisarda ◽  
Yassine Cherrak ◽  
Romain Kooger ◽  
Victoria Schmidt ◽  
Riccardo Pellarin ◽  
...  
Keyword(s):  
High Resolution ◽  
Secretion System ◽  
Type Vi Secretion System ◽  
Membrane Complex ◽  
Type Vi Secretion ◽  
Bacterial Type

scholarly journals Expression of the Type VI Secretion System 1 Component Hcp1 Is Indirectly Repressed by OpaR inVibrio parahaemolyticus

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Lizhi Ma ◽  
Yiquan Zhang ◽  
Xiaojuan Yan ◽  
Liping Guo ◽  
Li Wang ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Stress Responses ◽  
Structural Component ◽  
Vibrio Parahaemolyticus ◽  
Secretion System ◽  
Upstream Region ◽  
Bacterial Protein ◽  
Type Vi Secretion System ◽  
Type Vi Secretion ◽  
System 1

The type VI secretion system (T6SS) is bacterial protein injection machinery with roles in virulence, symbiosis, interbacterial interaction, antipathogenesis, and environmental stress responses. There are two T6SS loci, T6SS1 and T6SS2, in the two chromosomes ofVibrio parahaemolyticus, respectively. This work disclosed that the master quorum sensing (QS) regulator OpaR repressed the transcription ofhcp1encoding the structural component Hcp1 of T6SS1 inV. parahaemolyticus, indicating that QS had a negative regulatory action on T6SS1. A singleσ54-dependent promoter was transcribed forhcp1inV. parahaemolyticus, and its activity was repressed by the OpaR regulator. Since the OpaR protein could not bind to the upstream region ofhcp1, OpaR would repress the transcription ofhcp1in an indirect manner.

scholarly journals Bioinformatic Analysis of the Campylobacter jejuni Type VI Secretion System and Effector Prediction

2021 ◽  
Vol 12 ◽  
Author(s):  
Luca Robinson ◽  
Janie Liaw ◽  
Zahra Omole ◽  
Dong Xia ◽  
Arnoud H. M. van Vliet ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Variable Region ◽  
Pathogenicity Island ◽  
Bioinformatic Analysis ◽  
Secretion System ◽  
Open Reading Frames ◽  
Host Cells ◽  
Type Vi Secretion System ◽  
Bacterial Antagonism ◽  
Type Vi Secretion

The Type VI Secretion System (T6SS) has important roles relating to bacterial antagonism, subversion of host cells, and niche colonisation. Campylobacter jejuni is one of the leading bacterial causes of human gastroenteritis worldwide and is a commensal coloniser of birds. Although recently discovered, the T6SS biological functions and identities of its effectors are still poorly defined in C. jejuni. Here, we perform a comprehensive bioinformatic analysis of the C. jejuni T6SS by investigating the prevalence and genetic architecture of the T6SS in 513 publicly available genomes using C. jejuni 488 strain as reference. A unique and conserved T6SS cluster associated with the Campylobacter jejuni Integrated Element 3 (CJIE3) was identified in the genomes of 117 strains. Analyses of the T6SS-positive 488 strain against the T6SS-negative C. jejuni RM1221 strain and the T6SS-positive plasmid pCJDM202 carried by C. jejuni WP2-202 strain defined the “T6SS-containing CJIE3” as a pathogenicity island, thus renamed as Campylobacter jejuni Pathogenicity Island-1 (CJPI-1). Analysis of CJPI-1 revealed two canonical VgrG homologues, CJ488_0978 and CJ488_0998, harbouring distinct C-termini in a genetically variable region downstream of the T6SS operon. CJPI-1 was also found to carry a putative DinJ-YafQ Type II toxin-antitoxin (TA) module, conserved across pCJDM202 and the genomic island CJIE3, as well as several open reading frames functionally predicted to encode for nucleases, lipases, and peptidoglycan hydrolases. This comprehensive in silico study provides a framework for experimental characterisation of T6SS-related effectors and TA modules in C. jejuni.

scholarly journals The Type VI Secretion System Modulates Flagellar Gene Expression and Secretion in Citrobacter freundii and Contributes to Adhesion and Cytotoxicity to Host Cells

2015 ◽  
Vol 83 (7) ◽  
pp. 2596-2604 ◽  
Author(s):  
Liyun Liu ◽  
Shuai Hao ◽  
Ruiting Lan ◽  
Guangxia Wang ◽  
Di Xiao ◽  
...  
Keyword(s):  
Secretion System ◽  
Host Cells ◽  
Target Cells ◽  
Deletion Mutants ◽  
Citrobacter Freundii ◽  
Wild Type ◽  
Type Vi Secretion System ◽  
Content Type ◽  
Type Vi Secretion ◽  
Mutant Strains

The type VI secretion system (T6SS) as a virulence factor-releasing system contributes to virulence development of various pathogens and is often activated upon contact with target cells.Citrobacter freundiistrain CF74 has a complete T6SS genomic island (GI) that containsclpV,hcp-2, andvgrT6SS genes. We constructedclpV,hcp-2,vgr, and T6SS GI deletion mutants in CF74 and analyzed their effects on the transcriptome overall and, specifically, on the flagellar system at the levels of transcription and translation. Deletion of the T6SS GI affected the transcription of 84 genes, with 15 and 69 genes exhibiting higher and lower levels of transcription, respectively. Members of the cell motility class of downregulated genes of the CF74ΔT6SS mutant were mainly flagellar genes, including effector proteins, chaperones, and regulators. Moreover, the production and secretion of FliC were also decreased inclpV,hcp-2,vgr, or T6SS GI deletion mutants in CF74 and were restored upon complementation. In swimming motility assays, the mutant strains were found to be less motile than the wild type, and motility was restored by complementation. The mutant strains were defective in adhesion to HEp-2 cells and were restored partially upon complementation. Further, the CF74ΔT6SS, CF74ΔclpV, and CF74Δhcp-2mutants induced lower cytotoxicity to HEp-2 cells than the wild type. These results suggested that the T6SS GI in CF74 regulates the flagellar system, enhances motility, is involved in adherence to host cells, and induces cytotoxicity to host cells. Thus, the T6SS plays a wide-ranging role inC. freundii.

scholarly journals A New Front in Microbial Warfare—Delivery of Antifungal Effectors by the Type VI Secretion System

2019 ◽  
Vol 5 (2) ◽  
pp. 50 ◽  
Author(s):  
Katharina Trunk ◽  
Sarah J. Coulthurst ◽  
Janet Quinn
Keyword(s):  
Bacterial Species ◽  
Fungal Species ◽  
Secretion System ◽  
Effector Proteins ◽  
Primary Role ◽  
Bacterial Cells ◽  
Type Vi Secretion System ◽  
Type Vi Secretion ◽  
Bacteria And Fungi ◽  
Polymicrobial Communities

Microbes typically exist in mixed communities and display complex synergistic and antagonistic interactions. The Type VI secretion system (T6SS) is widespread in Gram-negative bacteria and represents a contractile nano-machine that can fire effector proteins directly into neighbouring cells. The primary role assigned to the T6SS is to function as a potent weapon during inter-bacterial competition, delivering antibacterial effectors into rival bacterial cells. However, it has recently emerged that the T6SS can also be used as a powerful weapon against fungal competitors, and the first fungal-specific T6SS effector proteins, Tfe1 and Tfe2, have been identified. These effectors act via distinct mechanisms against a variety of fungal species to cause cell death. Tfe1 intoxication triggers plasma membrane depolarisation, whilst Tfe2 disrupts nutrient uptake and induces autophagy. Based on the frequent coexistence of bacteria and fungi in microbial communities, we propose that T6SS-dependent antifungal activity is likely to be widespread and elicited by a suite of antifungal effectors. Supporting this hypothesis, homologues of Tfe1 and Tfe2 are found in other bacterial species, and a number of T6SS-elaborating species have been demonstrated to interact with fungi. Thus, we envisage that antifungal T6SS will shape many polymicrobial communities, including the human microbiota and disease-causing infections.

scholarly journals The Type VI Secretion System Encoded in Salmonella Pathogenicity Island 19 Is Required for Salmonella enterica Serotype Gallinarum Survival within Infected Macrophages

2013 ◽  
Vol 81 (4) ◽  
pp. 1207-1220 ◽  
Author(s):  
Carlos J. Blondel ◽  
Juan C. Jiménez ◽  
Lorenzo E. Leiva ◽  
Sergio A. Álvarez ◽  
Bernardo I. Pinto ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Pathogenicity Island ◽  
Secretion System ◽  
Host Cells ◽  
Economic Losses ◽  
Type Vi Secretion System ◽  
Content Type ◽  
Type Vi Secretion ◽  
Core Components

ABSTRACTSalmonella entericaserotype Gallinarum is the causative agent of fowl typhoid, a disease characterized by high morbidity and mortality that causes major economic losses in poultry production. We have reported thatS. Gallinarum harbors a type VI secretion system (T6SS) encoded inSalmonellapathogenicity island 19 (SPI-19) that is required for efficient colonization of chicks. In the present study, we aimed to characterize the SPI-19 T6SS functionality and to investigate the mechanisms behind the phenotypes previously observedin vivo. Expression analyses revealed that SPI-19 T6SS core components are expressed and produced underin vitrobacterial growth conditions. However, secretion of the structural/secreted components Hcp1, Hcp2, and VgrG to the culture medium could not be determined, suggesting that additional signals are required for T6SS-dependent secretion of these proteins.In vitrobacterial competition assays failed to demonstrate a role for SPI-19 T6SS in interbacterial killing. In contrast, cell culture experiments with murine and avian macrophages (RAW264.7 and HD11, respectively) revealed production of a green fluorescent protein-tagged version of VgrG soon afterSalmonellauptake. Furthermore, infection of RAW264.7 and HD11 macrophages with deletion mutants of SPI-19 or strains with genes encoding specific T6SS core components (clpVandvgrG) revealed that SPI-19 T6SS contributes toS. Gallinarum survival within macrophages at 20 h postuptake. SPI-19 T6SS function was not linked toSalmonella-induced cytotoxicity or cell death of infected macrophages, as has been described for other T6SS. Our data indicate that SPI-19 T6SS corresponds to a novel tool used bySalmonellato survive within host cells.

scholarly journals AT6SS trans-kingdom effector is required for the delivery of a novel antibacterial toxin in Pseudomonas aeruginosa

2019 ◽  
Author(s):  
Benjamin Berni ◽  
Chantal Soscia ◽  
Djermoun Sarah ◽  
Ize Bérengère ◽  
Sophie Bleves
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Surrounding Medium ◽  
Host Cells ◽  
List Type ◽  
Type Vi Secretion System ◽  
Multiple Strategies ◽  
Type Vi Secretion ◽  
Host Infection ◽  
Opportunist Pathogen

AbstractPseudomonas aeruginosa has evolved multiple strategies to disarm and take advantage of its host. For this purpose this opportunist pathogen has particularly developed protein secretion in the surrounding medium or injection into host cells. Among this, the Type VI Secretion System (T6SS) is utilized to deliver effectors into eukaryotic host as well as target bacteria. It assembles into a contractile bacteriophage tail-like structure that functions like a crossbow, injecting an arrow loaded with effectors into the target cell. The repertoire of T6SS antibacterial effectors of P. aeruginosa is remarkably broad to promote environmental adaptation and survival in various bacterial communities, and presumably in the eukaryotic host too.Here we report the discovery a novel pair of antibacterial effector and immunity of P. aeruginosa, Tle3 and Tli3. Tli3 neutralizes the toxicity of Tle3 in the periplasm to protect from fratricide intoxication. The characterization of the secretion mechanism of Tle3 indicates that it requires a cytoplasmic adaptor, Tla3, to be targeted and loaded onto the VgrG2b spike and thus delivered by the H2-T6SS machinery. Tla3 is different from the other adaptors discovered so far, and defines a novel family among T6SS.Interestingly this led us to discover that VgrG2b that we previously characterized as an anti-eukaryotic effector possesses an antibacterial activity as well, as it is toxic towards Escherichia coli. VgrG2b is thus a novel trans-kingdom effector targeting both bacteria and eukaryotes. VgrG2b represents an interesting target for fighting against P. aeruginosa in the environment and in the context of host infection.HighlightsTle3 and Tli3 are a novel pair of antibacterial toxin and immunity of P. aeruginosaTla3 recruits Tle3 in the cytoplasm, and targets it to VgrG2bVgrG2b is required for Tle3 delivery into target bacteria by the H2-T6SSTla3 defines a novel type of T6SS adaptor with a DUF2875VgrG2b is a new trans-kingdom effector targeting both bacteria and eukaryotes

scholarly journals VipA N-terminal linker and VipB-VipB interaction modulate the contraction of Type VI secretion system sheath

2017 ◽  
Author(s):  
Maximilian Brackmann ◽  
Jing Wang ◽  
Marek Basler
Keyword(s):  
Protein Translocation ◽  
Secretion System ◽  
Mass Spectrometry Analysis ◽  
Target Cells ◽  
Extended State ◽  
Type Vi Secretion System ◽  
Secretion Systems ◽  
Spectrometry Analysis ◽  
Type Vi Secretion ◽  
Bacterial Type

AbstractSecretion systems are essential for bacteria to survive and manipulate their environment. The bacterial Type VI Secretion System (T6SS) generates the force needed for protein translocation by the contraction of a long polymer called sheath, which is composed of interconnected VipA/VipB subunits forming a six-start helix. The mechanism of T6SS sheath contraction and the structure of its extended state are unknown. Here we show that elongating the N-terminal VipA linker or eliminating charge of a specific VipB residue abolished sheath contraction and delivery of effectors into target cells. The assembly of the non-contractile sheaths was dependent on the baseplate component TssE and mass-spectrometry analysis identified Hcp, VgrG and other components of the T6SS baseplate specifically associated with stable non-contractile sheaths. The ability to lock T6SS in the pre-firing state opens new possibilities for understanding its mode of action.

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