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https://www.readbyqxmd.com/read/28650463/type-vi-secretion-tssk-baseplate-protein-exhibits-structural-similarity-with-phage-receptor-binding-proteins-and-evolved-to-bind-the-membrane-complex
#1
Van Son Nguyen, Laureen Logger, Silvia Spinelli, Pierre Legrand, Thi Thanh Huyen Pham, Thi Trang Nhung Trinh, Yassine Cherrak, Abdelrahim Zoued, Aline Desmyter, Eric Durand, Alain Roussel, Christine Kellenberger, Eric Cascales, Christian Cambillau
The type VI secretion system (T6SS) is a multiprotein machine widespread in Gram-negative bacteria that delivers toxins into both eukaryotic and prokaryotic cells. The mechanism of action of the T6SS is comparable to that of contractile myophages. The T6SS builds a tail-like structure made of an inner tube wrapped by a sheath, assembled under an extended conformation. Contraction of the sheath propels the inner tube towards the target cell. The T6SS tail is assembled on a platform-the baseplate-which is functionally similar to bacteriophage baseplates...
June 26, 2017: Nature Microbiology
https://www.readbyqxmd.com/read/28632016/the-bacteroides-fragilis-pathogenicity-island-links-virulence-and-strain-competition
#2
Benjamin W Casterline, Aaron L Hecht, Vivian M Choi, Juliane Bubeck Wardenburg
The mature microbiome is a stable ecosystem that resists perturbation despite constant host exposure to exogenous microbes. However, the microbial mechanisms determining microbiome development and composition are poorly understood. We recently demonstrated that a non-toxigenic B. fragilis (NTBF) strain restricts enteric colonization by an enterotoxigenic (ETBF) strain dependent on a type VI secretion system (T6SS). We show here that a second enterotoxigenic strain is competent to colonize, dependent on the Bacteroides fragilis pathogenicity island (BFPAI)...
February 23, 2017: Gut Microbes
https://www.readbyqxmd.com/read/28621333/francisella-requires-dynamic-type-vi-secretion-system-and-clpb-to-deliver-effectors-for-phagosomal-escape
#3
Maj Brodmann, Roland F Dreier, Petr Broz, Marek Basler
Francisella tularensis is an intracellular pathogen that causes the fatal zoonotic disease tularaemia. Critical for its pathogenesis is the ability of the phagocytosed bacteria to escape into the cell cytosol. For this, the bacteria use a non-canonical type VI secretion system (T6SS) encoded on the Francisella pathogenicity island (FPI). Here we show that in F. novicida T6SS assembly initiates at the bacterial poles both in vitro and within infected macrophages. T6SS dynamics and function depends on the general purpose ClpB unfoldase, which specifically colocalizes with contracted sheaths and is required for their disassembly...
June 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/28618272/shigella-sonnei-encodes-a-functional-t6ss-used-for-interbacterial-competition-and-niche-occupancy
#4
Mark C Anderson, Pascale Vonaesch, Azadeh Saffarian, Benoit S Marteyn, Philippe J Sansonetti
Shigella is a leading cause of dysentery worldwide, with the majority of infections caused by two subgroups, S. flexneri and S. sonnei. Although S. flexneri has been highly prevalent in low-income countries, global development has brought an increase in S. sonnei at the expense of S. flexneri. However, the mechanisms behind this shift are not understood. Here we report that S. sonnei, but not S. flexneri, encodes a type VI secretion system (T6SS) that provides a competitive advantage in the gut. S. sonnei competes against E...
June 14, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28602424/using-force-to-punch-holes-mechanics-of-contractile-nanomachines
#5
REVIEW
Maximilian Brackmann, Sergey Nazarov, Jing Wang, Marek Basler
Using physical force to translocate macromolecules across a membrane has the advantage of being a universal solution independent of the properties of the target membrane. However, physically punching a stiff membrane is not a trivial task and three things are necessary for success: a sharp tip, a source of energy, and the ability to strongly bind to the target. In this review we describe the basic mechanism of membrane puncturing by contractile nanomachines with a focus on the T4 phage, R-type pyocin, and the bacterial Type VI secretion system (T6SS) based on recent studies of the structures and dynamics of their assembly...
June 8, 2017: Trends in Cell Biology
https://www.readbyqxmd.com/read/28594921/t6ss-the-bacterial-fight-club-in-the-host-gut
#6
Thibault G Sana, Kyler A Lugo, Denise M Monack
No abstract text is available yet for this article.
June 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28584154/pa3225-is-a-transcriptional-repressor-of-antibiotic-resistance-mechanisms-in-pseudomonas-aeruginosa
#7
Clayton W Hall, Li Zhang, Thien-Fah Mah
The tssABC1 locus is part of the Hcp secretion island (HSI) -I type VI secretion system (T6SS) in Pseudomonas aeruginosa Previous work has implicated the tssC1 gene in P. aeruginosa biofilm-specific antibiotic resistance, and tssC1 is preferentially expressed in biofilms compared to planktonic cells. Using a DNA-dependent protein pulldown approach, we discovered PA3225, an uncharacterised LysR-type transcriptional regulator that specifically bound to the tssABC1 upstream regulatory region. Deletion of PA3225 led to a two-fold decrease in tssA1 expression in planktonic cells compared to wild-type, and tssA1 expression was slightly reduced in ΔPA3225 biofilms compared to wild-type biofilms...
June 5, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28580353/development-and-validation-of-a-novel-real-time-assay-for-the-detection-and-quantification-of-vibrio-cholerae
#8
Ridwan Bin Rashid, Jannatul Ferdous, Suhella Tulsiani, Peter Kjaer Mackie Jensen, Anowara Begum
Vibrio cholerae O1 and O139 has been known for its ability to cause epidemics. These strains produce cholera toxin which is the main cause of secretory diarrhea. V. cholerae non-O1 and non-O139 strains are also capable of causing gastroenteritis as well as septicemia and peritonitis. It has been proven that virulence factors such as T6SS, hapA, rtxA, and hlyA are present in almost all V. cholerae strains. It is imperative that viable but non-culturable cells of V. cholerae are also detected since they are also known to cause diarrhea...
2017: Frontiers in Public Health
https://www.readbyqxmd.com/read/28536678/the-role-and-mechanism-of-erythrocyte-invasion-by-francisella-tularensis
#9
Deanna M Schmitt, Rebecca Barnes, Taylor Rogerson, Ashley Haught, Leanne K Mazzella, Matthew Ford, Tricia Gilson, James W-M Birch, Anders Sjöstedt, Douglas S Reed, Jonathan M Franks, Donna B Stolz, James Denvir, Jun Fan, Swanthana Rekulapally, Donald A Primerano, Joseph Horzempa
Francisella tularensis is an extremely virulent bacterium that can be transmitted naturally by blood sucking arthropods. During mammalian infection, F. tularensis infects numerous types of host cells, including erythrocytes. As erythrocytes do not undergo phagocytosis or endocytosis, it remains unknown how F. tularensis invades these cells. Furthermore, the consequence of inhabiting the intracellular space of red blood cells (RBCs) has not been determined. Here, we provide evidence indicating that residing within an erythrocyte enhances the ability of F...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28487352/in-vivo-structures-of-an-intact-type-vi-secretion-system-revealed-by-electron-cryotomography
#10
Yi-Wei Chang, Lee A Rettberg, Davi R Ortega, Grant J Jensen
The type VI secretion system (T6SS) is a versatile molecular weapon used by many bacteria against eukaryotic hosts or prokaryotic competitors. It consists of a cytoplasmic bacteriophage tail-like structure anchored in the bacterial cell envelope via a cytoplasmic baseplate and a periplasmic membrane complex. Rapid contraction of the sheath in the bacteriophage tail-like structure propels an inner tube/spike complex through the target cell envelope to deliver effectors. While structures of purified contracted sheath and purified membrane complex have been solved, because sheaths contract upon cell lysis and purification, no structure is available for the extended sheath...
May 9, 2017: EMBO Reports
https://www.readbyqxmd.com/read/28452085/use-of-chimeric-type-iv-secretion-systems-to-define-contributions-of-outer-membrane-subassemblies-for-contact-dependent-translocation
#11
Jay E Gordon, Tiago R D Costa, Roosheel S Patel, Christian Gonzalez-Rivera, Mayukh K Sarkar, Elena V Orlova, Gabriel Waksman, Peter J Christie
Recent studies have shown that conjugation systems of Gram-negative bacteria are composed of distinct inner and outer membrane core complexes (IMCs and OMCCs, respectively). Here, we characterized the OMCC by focusing first on a cap domain that forms a channel across the outer membrane. Strikingly, the OMCC caps of the Escherichia coli pKM101 Tra and Agrobacterium tumefaciens VirB/VirD4 systems are completely dispensable for substrate transfer, but required for formation of conjugative pili. The pKM101 OMCC cap and extended pilus also are dispensable for activation of a Pseudomonas aeruginosa type VI secretion system (T6SS)...
April 27, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28448786/microbiological-features-and-clinical-impact-of-the-type-vi-secretion-system-t6ss-in-acinetobacter-baumannii-isolates-causing-bacteremia
#12
Jungok Kim, Ji-Young Lee, Haejeong Lee, Ji Young Choi, Dae Hun Kim, Yu Mi Wi, Kyong Ran Peck, Kwan Soo Ko
We investigated the genetic background and microbiological features of T6SS-positive Acinetobacter baumannii isolates and clinical impact of the T6SS in patients with A. baumannii bacteremia. One hundred and 62 A. baumannii isolates from patients with bacteremia in 2 tertiary-care hospitals in Korea were included in this study. Approximately one-third (51/162, 31.5%) of the A. baumannii clinical isolates possessed the hcp gene, and the hcp-positive isolates were found in several genotypes in multilocus sequence typing...
April 27, 2017: Virulence
https://www.readbyqxmd.com/read/28441105/transcriptomic-dissection-of-the-horizontally-acquired-response-regulator-esrb-reveals-its-global-regulatory-roles-in-the-physiological-adaptation-and-activation-of-t3ss-and-the-cognate-effector-repertoire-in-edwardsiella-piscicida-during-infection-toward-turbot
#13
Yang Liu, Luyao Zhao, Minjun Yang, Kaiyu Yin, Xiaohui Zhou, Ka Yin Leung, Qin Liu, Yuanxing Zhang, Qiyao Wang
Edwardsiella piscicida is the leading pathogen threatening worldwide aquaculture industries. The 2-component system (TCS) EsrA-EsrB is essential for the pathogenesis of this bacterium. However, little is known about the regulon and regulatory mechanism of EsrA-EsrB or about the factors that mediate the interaction of TCS with bacterial hosts. Here, our RNA-seq analysis indicated that EsrB strongly induces type III and type VI secretion systems (T3/T6SS) expression and that it modulates the expression of both physiology- and virulence-associated genes in E...
April 25, 2017: Virulence
https://www.readbyqxmd.com/read/28432099/acute-hepatopancreatic-necrosis-disease-ahpnd-causing-vibrio-parahaemolyticus-strains-maintain-an-antibacterial-type-vi-secretion-system-with-versatile-effector-repertoires
#14
Peng Li, Lisa N Kinch, Ann Ray, Ankur B Dalia, Qian Cong, Linda M Nunan, Andrew Camilli, Nick V Grishin, Dor Salomon, Kim Orth
Acute hepatopancreatic necrosis disease (AHPND) is a newly emerging shrimp disease that has severely damaged the global shrimp industry. AHPND is caused by toxic strains of Vibrio parahaemolyticus (V. parahaemolyticus) that have acquired a "selfish plasmid" encoding the deadly binary toxins PirA(vp)/PirB(vp) To better understand the repertoire of virulence factors in AHPND-causing V. parahaemolyticus, we conducted a comparative analysis using genome sequences of the clinical strain RIMD2210633, environmental non-AHPND and toxic AHPND isolates of V...
April 21, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28430102/variable-virulence-phenotype-of-xenorhabdus-bovienii-%C3%AE-proteobacteria-enterobacteriaceae-in-the-absence-of-their-vector-hosts
#15
John G McMullen, Rebecca McQuade, Jean-Claude Ogier, Sylvie Pagès, Sophie Gaudriault, S Patricia Stock
Xenorhabdus bovienii bacteria have a dual lifestyle: they are mutualistic symbionts to many species of Steinernema nematodes and are pathogens to a wide array of insects. Previous studies have shown that virulence of X.bovienii-Steinernema spp. pairs decreases when the nematodes associate with non-cognate bacterial strains. However, the virulence of the X. bovienii strains alone has not been fully investigated. In this study, we characterized the virulence of nine X. bovienii strains in Galleria mellonella and Spodoptera littoralis and performed a comparative genomic analysis to correlate observed phenotypes with strain genotypes...
April 22, 2017: Microbiology
https://www.readbyqxmd.com/read/28424671/functional-characterization-and-conditional-regulation-of-the-type-vi-secretion-system-in-vibrio-fluvialis
#16
Yuanming Huang, Pengcheng Du, Meng Zhao, Wei Liu, Yu Du, Baowei Diao, Jie Li, Biao Kan, Weili Liang
Vibrio fluvialis is an emerging foodborne pathogen of increasing public health concern. The mechanism(s) that contribute to the bacterial survival and disease are still poorly understood. In other bacterial species, type VI secretion systems (T6SSs) are known to contribute to bacterial pathogenicity by exerting toxic effects on host cells or competing bacterial species. In this study, we characterized the genetic organization and prevalence of two T6SS gene clusters (VflT6SS1 and VflT6SS2) in V. fluvialis. VflT6SS2 harbors three "orphan" hcp-vgrG modules and was more prevalent than VflT6SS1 in our isolates...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28421913/type-vi-secretion-systems-of-erwinia-amylovora-contribute-to-bacterial-competition-virulence-and-exopolysaccharide-production
#17
Yanli Tian, Yuqiang Zhao, Linye Shi, Zhongli Cui, Baishi Hu, Youfu Zhao
The type VI secretion system (T6SS) plays a major role in mediating interbacterial competition and might contribute to virulence in plant pathogenic bacteria. However, the role of T6SS in Erwinia amylovora remains unknown. In this study, 33 deletion mutants within three T6SS clusters were generated in E. amylovora strain NCPPB1665. Our results showed that all 33 mutants displayed reduced antibacterial activities against Escherichia coli as compared with that of the wild-type (WT) strain, indicating that Erwinia amylovora T6SS are functional...
June 2017: Phytopathology
https://www.readbyqxmd.com/read/28357328/francisella-iglg-protein-and-the-duf4280-proteins-paar-like-proteins-in-non-canonical-type-vi-secretion-systems
#18
COMMENT
Claire Lays, Eric Tannier, Thomas Henry
Type VI secretion systems (T6SS) are bacterial molecular machines translocating effector proteins into target cells. T6SS are widely present in Gram-negative bacteria where they predominantly act to kill neighboring bacteria. This secretion system is reminiscent of the tail of contractile bacteriophages and consists of a contractile sheath anchored in the bacterial envelope and an inner tube made of stacks of the Hcp protein. The Hcp tube is capped with a VgrG trimer and a spike protein termed PAAR, which acts as the membrane-puncturing device...
October 29, 2016: Microbial Cell
https://www.readbyqxmd.com/read/28348642/metagenomic-analysis-of-a-complex-community-present-in-pond-sediment
#19
Vivek Negi, Rup Lal
The metagenomic profiling of complex communities is gaining immense interest across the scientific community. A complex community present in the pond sediment of a water body located close to a hexachlorocyclohexane (HCH) production site of the Indian Pesticide Limited (IPL) (Chinhat, Lucknow) was selected in an attempt to identify and analyze the unique microbial diversity and functional profile of the site. In this study, we supplement the metagenomic study of pond sediment with a variety of binning approaches along with an in depth functional analysis...
2017: Journal of Genomics
https://www.readbyqxmd.com/read/28348410/a-pseudomonas-t6ss-effector-recruits-pqs-containing-outer-membrane-vesicles-for-iron-acquisition
#20
Jinshui Lin, Weipeng Zhang, Juanli Cheng, Xu Yang, Kaixiang Zhu, Yao Wang, Gehong Wei, Pei-Yuan Qian, Zhao-Qing Luo, Xihui Shen
Iron sequestration by host proteins contributes to the defence against bacterial pathogens, which need iron for their metabolism and virulence. A Pseudomonas aeruginosa mutant lacking all three known iron acquisition systems retains the ability to grow in media containing iron chelators, suggesting the presence of additional pathways involved in iron uptake. Here we screen P. aeruginosa mutants defective in growth in iron-depleted media and find that gene PA2374, proximal to the type VI secretion system H3 (H3-T6SS), functions synergistically with known iron acquisition systems...
March 28, 2017: Nature Communications
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