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Type VI secretion

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https://www.readbyqxmd.com/read/28703218/the-type-vi-secretion-system-sheath-assembles-at-the-end-distal-from-the-membrane-anchor
#1
Andrea Vettiger, Julius Winter, Lin Lin, Marek Basler
The bacterial Type VI secretion system (T6SS) delivers proteins into target cells using fast contraction of a long sheath anchored to the cell envelope and wrapped around an inner Hcp tube associated with the secreted proteins. Mechanisms of sheath assembly and length regulation are unclear. Here we study these processes using spheroplasts formed from ampicillin-treated Vibrio cholerae. We show that spheroplasts secrete Hcp and deliver T6SS substrates into neighbouring cells. Imaging of sheath dynamics shows that the sheath length correlates with the diameter of spheroplasts and may reach up to several micrometres...
July 13, 2017: Nature Communications
https://www.readbyqxmd.com/read/28690981/fnr-regulates-the-expression-of-important-virulence-factors-contributing-to-the-pathogenicity-of-avian-pathogenic-escherichia-coli
#2
Nicolle L Barbieri, Jessica A Vande Vorde, Alison R Baker, Fabiana Horn, Ganwu Li, Catherine M Logue, Lisa K Nolan
Avian pathogenic Escherichia coli (APEC) is the etiologic agent of colibacillosis, an important cause of morbidity and mortality in poultry. Though, many virulence factors associated with APEC pathogenicity are known, their regulation remains unclear. FNR (fumarate and nitrate reduction) is a well-known global regulator that works as an oxygen sensor and has previously been described as a virulence regulator in bacterial pathogens. The goal of this study was to examine the role of FNR in the regulation of APEC virulence factors, such as Type I fimbriae, and processes such as adherence and invasion, type VI secretion, survival during oxidative stress, and growth in iron-restricted environments...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28690319/interbacterial-predation-as-a-strategy-for-dna-acquisition-in-naturally-competent-bacteria
#3
REVIEW
Jan-Willem Veening, Melanie Blokesch
Natural competence enables bacteria to take up exogenous DNA. The evolutionary function of natural competence remains controversial, as imported DNA can act as a source of substrates or can be integrated into the genome. Exogenous homologous DNA can also be used for genome repair. In this Opinion article, we propose that predation of non-related neighbouring bacteria coupled with competence regulation might function as an active strategy for DNA acquisition. Competence-dependent kin-discriminated killing has been observed in the unrelated bacteria Vibrio cholerae and Streptococcus pneumoniae...
July 10, 2017: Nature Reviews. Microbiology
https://www.readbyqxmd.com/read/28674938/herbaspirillum-rubrisubalbicans-a-mild-pathogen-impairs-growth-of-rice-by-augmenting-ethylene-levels
#4
Glaucio Valdameri, Dayane Alberton, Vivian Rotuno Moure, Thiago Borba Kokot, Caroline Kukolj, Liziane Cristina Campos Brusamarello-Santos, Rose Adele Monteiro, Fabio de Oliveira Pedrosa, Emanuel Maltempi de Souza
Herbaspirillum rubrisubalbicans decreases growth of rice. Inoculation of rice with H. rubrisubalbicans increased the ACCO mRNA levels and ethylene production. The H. rubrisubalbicans rice interactions were further characterized by proteomic approach. Herbaspirillum rubrisubalbicans is a well-known growth-promoting rhizobacteria that can also act as a mild phyto-pathogen. During colonisation of rice, RT-qPCR analyses showed that H. rubrisubalbicans up-regulates the methionine recycling pathway as well as phyto-siderophore synthesis genes...
July 3, 2017: Plant Molecular Biology
https://www.readbyqxmd.com/read/28673999/rsma-and-amrz-orchestrate-the-assembly-of-all-three-type-vi-secretion-systems-in-pseudomonas-aeruginosa
#5
Luke P Allsopp, Thomas E Wood, Sophie A Howard, Federica Maggiorelli, Laura M Nolan, Sarah Wettstadt, Alain Filloux
The type VI secretion system (T6SS) is a weapon of bacterial warfare and host cell subversion. The Gram-negative pathogen Pseudomonas aeruginosa has three T6SSs involved in colonization, competition, and full virulence. H1-T6SS is a molecular gun firing seven toxins, Tse1-Tse7, challenging survival of other bacteria and helping P. aeruginosa to prevail in specific niches. The H1-T6SS characterization was facilitated through studying a P. aeruginosa strain lacking the RetS sensor, which has a fully active H1-T6SS, in contrast to the parent...
July 3, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28667634/quantitative-determination-of-anti-bacterial-activity-during-bacterial-co-culture
#6
Juliana Alcoforado Diniz, Birte Hollmann, Sarah J Coulthurst
Anti-bacterial activity assays are an important tool in the assessment of the ability of one bacterium to kill or inhibit the growth of another, for example during the study of the Type VI secretion system (T6SS) and the anti-bacterial toxins it secretes. The method we describe here can detect the ability of a bacterial strain to kill or inhibit other bacterial cells in a contact-dependent manner when co-cultured on an agar surface. It is particularly useful since it enumerates the recovery of viable target cells and thus enables quantification of the anti-bacterial activity...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28667632/monitoring-effector-translocation-using-the-tem-1-beta-lactamase-reporter-system
#7
Julie Allombert, Anne Vianney, Xavier Charpentier
Among the bacterial secretion systems, the Type III, IV, and VI secretion systems enable bacteria to secrete proteins directly into a target cell. This specific form of secretion, referred to as translocation, is essential for a number of pathogens to alter or kill targeted cells. The translocated proteins, called effector proteins, can directly interfere with the normal processes of the targeted cells, preventing elimination of pathogens and promoting their multiplication. The function of effector proteins varies greatly depending on the considered pathogen and the targeted cell...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28667630/screening-for-secretion-of-the-type-vi-secretion-system-protein-hcp-by-enzyme-linked-immunosorbent-assay-and-colony-blot
#8
Brent S Weber, Pek Man Ly, Mario F Feldman
The bacterial type VI secretion system (T6SS) is a secretory apparatus encoded by many Gram-negative bacteria. The T6SS facilitates the secretion and injection of toxic effector proteins into host cells, providing a competitive advantage to bacteria encoding this machinery. The activity of the T6SS can be monitored by probing for the conserved tubule component Hcp, which is secreted to the supernatants by the T6SS. Detection of Hcp in culture supernatants is indicative of an active T6SS, but this secretion system is often tightly regulated or inactive under laboratory conditions and different bacterial strains display differing Hcp secretion phenotypes...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28667622/large-complexes-cloning-strategy-production-and-purification
#9
Eric Durand, Roland Lloubes
Membrane proteins can assemble and form complexes in the cell envelope. In Gram-negative bacteria, a number of multiprotein complexes, including secretion systems, efflux pumps, molecular motors, and pilus assembly machines, comprise proteins from the inner and outer membranes. Besides the structures of isolated soluble domains, only a few atomic structures of these assembled molecular machines have been elucidated. To better understand the function and to solve the structure of protein complexes, it is thus necessary to design dedicated production and purification processes...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28667615/protein-protein-interactions-co-immunoprecipitation
#10
Jer-Sheng Lin, Erh-Min Lai
Proteins often do not function as single substances but rather as team players in a dynamic network. Growing evidence shows that protein-protein interactions are crucial in many biological processes in living cells. Genetic (such as yeast two-hybrid, Y2H) and biochemical (such as co-immunoprecipitation, co-IP) methods are the methods commonly used at the beginning of a study to identify the interacting proteins. Immunoprecipitation (IP), a method using a target protein-specific antibody in conjunction with Protein A/G affinity beads, is a powerful tool to identify molecules that interact with specific proteins...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28667612/protein-protein-interactions-yeast-two-hybrid-system
#11
Jer-Sheng Lin, Erh-Min Lai
The yeast two-hybrid system is a powerful and commonly used genetic tool to investigate interactions between artificial fusion proteins inside the nucleus of yeast. Here we describe how to use the Matchmaker GAL4-based yeast two-hybrid system to detect the interaction of the Agrobacterium type VI secretion system (T6SS) sheath components TssB and TssC41. The bait and prey gene are expressed as a fusion to the GAL4 DNA-binding domain (DNA-BD) and GAL4 activation domain (AD, prey/library fusion protein) respectively...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28664151/type-vi-secretion-effectors-methodologies-and-biology
#12
REVIEW
Yun-Wei Lien, Erh-Min Lai
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...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28654053/assembly-and-tracking-of-microbial-community-development-within-a-microwell-array-platform
#13
Andrea C Timm, Michelle C Halsted, Jared L Wilmoth, Scott T Retterer
The development of microbial communities depends on a combination of complex deterministic and stochastic factors that can dramatically alter the spatial distribution and activities of community members. We have developed a microwell array platform that can be used to rapidly assemble and track thousands of bacterial communities in parallel. This protocol highlights the utility of the platform and describes its use for optically monitoring the development of simple, two-member communities within an ensemble of arrays within the platform...
June 6, 2017: Journal of Visualized Experiments: JoVE
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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