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Type vi secretion system

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https://www.readbyqxmd.com/read/28632016/the-bacteroides-fragilis-pathogenicity-island-links-virulence-and-strain-competition
#1
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
#2
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
#3
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/28618206/grazing-of-leaf-associated-cercomonads-protists-rhizaria-cercozoa-structures-bacterial-community-composition-and-function
#4
Sebastian Flues, David Bass, Michael Bonkowski
Preferential food selection in protists is well documented, but we still lack basic understanding on how protist predation modifies the taxonomic and functional composition of bacterial communities. We conducted feeding trials using leaf-associated cercomonad Cercozoa by incubating them on a standardized, diverse bacterial community washed from plant leaves. We used a shotgun metagenomics approach to investigate the taxonomic and functional changes of the bacterial community after five days protist predation upon bacteria...
June 15, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28606056/comparative-genome-and-transcriptome-analysis-reveals-distinctive-surface-characteristics-and-unique-physiological-potentials-of-pseudomonas-aeruginosa-atcc-27853
#5
Huiluo Cao, Yong Lai, Salim Bougouffa, Zeling Xu, Aixin Yan
BACKGROUND: Pseudomonas aeruginosa ATCC 27853 was isolated from a hospital blood specimen in 1971 and has been widely used as a model strain to survey antibiotics susceptibilities, biofilm development, and metabolic activities of Pseudomonas spp.. Although four draft genomes of P. aeruginosa ATCC 27853 have been sequenced, the complete genome of this strain is still lacking, hindering a comprehensive understanding of its physiology and functional genome. RESULTS: Here we sequenced and assembled the complete genome of P...
June 12, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28602424/using-force-to-punch-holes-mechanics-of-contractile-nanomachines
#6
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/28591848/comparative-genomics-of-free-living-gamma-proteobacteria-pathogenesis-related-genes-or-interaction-related-genes
#7
Mirna Vázquez-Rosas-Landa, Gabriel Yaxal Ponce-Soto, Luis E Eguiarte, V Souza
Bacteria have numerous strategies to interact with them and with their environment. However, genes associated with these interactions are usually cataloged as pathogenic. To understand the role that these genes have not only in pathogenesis but also in bacterial interactions, we compared the genomes of eight bacteria from human-impacted environments with free-living bacteria from the Cuatro Ciénegas Basin (CCB), a relatively pristine oligotrophic site. Fifty-one genomes from CCB bacteria, including Pseudomonas, Vibrio, Photobacterium, and Aeromonas were analyzed...
June 7, 2017: Pathogens and Disease
https://www.readbyqxmd.com/read/28584154/pa3225-is-a-transcriptional-repressor-of-antibiotic-resistance-mechanisms-in-pseudomonas-aeruginosa
#8
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/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/28536672/response-to-bile-salts-in-clinical-strains-of-acinetobacter-baumannii-lacking-the-adeabc-efflux-pump-virulence-associated-with-quorum-sensing
#10
Maria López, Lucia Blasco, Eva Gato, Astrid Perez, Laura Fernández-Garcia, Luis Martínez-Martinez, Felipe Fernández-Cuenca, Jesús Rodríguez-Baño, Alvaro Pascual, German Bou, Maria Tomás
Introduction:Acinetobacter baumannii is an opportunistic nosocomial pathogen associated with multiple infections. This pathogen usually colonizes (first stage of microbial infection) host tissues that are in contact with the external environment. As one of the sites of entry in human hosts is the gastrointestinal tract, the pathogen must be capable of tolerating bile salts. However, studies analyzing the molecular characteristics involved in the response to bile salts in clinical strains of A. baumannii are scarce...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28522707/draft-genome-sequence-of-the-luminescent-strain-vibrio-campbellii-lb102-isolated-from-a-black-tiger-shrimp-penaeus-monodon-broodstock-rearing-system
#11
Sujeet Kumar, Ashok Kumar Jangam, V Akhil, Vidya Rajendran, Vinaya Kumar Katneni, J Joseph Sahaya Rajan, Monendra Grover, Viswas Konasagara Nagaleekar, S V Alavandi, K K Vijayan
We report here the genome sequence of Vibrio campbellii LB102, isolated from the broodstock rearing system of a shrimp hatchery in India. Sequence analysis revealed the presence of effector toxins of the type III (YopT, sharing 39% identity with Yersinia pestis) and type VI (VgrG-3 and hemolysin coregulated protein of V. cholerae) secretion systems.
May 18, 2017: Genome Announcements
https://www.readbyqxmd.com/read/28487352/in-vivo-structures-of-an-intact-type-vi-secretion-system-revealed-by-electron-cryotomography
#12
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/28474537/physioxia-promotes-the-articular-chondrocyte-like-phenotype-in-human-chondroprogenitor-derived-self-organized-tissue
#13
Devon E Anderson, Brandon Markway, Kenneth J Weekes, Helen E McCarthy, Brian Johnstone
INTRODUCTION: Biomaterial-based tissue engineering has not successfully reproduced the structural architecture or functional mechanical properties of native articular cartilage. In scaffold-free tissue engineering systems, cells secrete and organize the entire extracellular matrix over time in response to environmental signals, such as oxygen level. In this study, we investigated the effect of oxygen on the formation of neocartilage from human-derived chondrogenic cells. METHODS: Articular chondrocytes (ACs) and articular cartilage progenitor cells (ACPs) derived from healthy human adults were guided toward cell condensation by centrifugation onto plate inserts that were uncoated or coated with either agarose or fibronectin...
May 5, 2017: Tissue Engineering. Part A
https://www.readbyqxmd.com/read/28469601/comparative-genomics-and-transcriptional-analysis-of-flavobacterium-columnare-strain-atcc-49512
#14
Hasan C Tekedar, Attila Karsi, Joseph S Reddy, Seong W Nho, Safak Kalindamar, Mark L Lawrence
Flavobacterium columnare is a Gram-negative fish pathogen causing columnaris disease in wild and cultured fish species. Although the pathogen is widespread in aquatic environments and fish worldwide, little is known about biology of F. columnare and mechanisms of columnaris disease pathogenesis. Previously we presented the complete genome sequence of F. columnare strain ATCC 49512. Here we present a comparison of the strain ATCC 49512 genome to four other Flavobacterium genomes. In this analysis, we identified predicted proteins whose functions indicate F...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28452085/use-of-chimeric-type-iv-secretion-systems-to-define-contributions-of-outer-membrane-subassemblies-for-contact-dependent-translocation
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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