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https://www.readbyqxmd.com/read/28910638/the-landscape-of-type-vi-secretion-across-human-gut-microbiomes-reveals-its-role-in-community-composition
#1
Adrian J Verster, Benjamin D Ross, Matthew C Radey, Yiqiao Bao, Andrew L Goodman, Joseph D Mougous, Elhanan Borenstein
Although gut microbiome composition is well defined, the mechanisms underlying community assembly remain poorly understood. Bacteroidales possess three genetic architectures (GA1-3) of the type VI secretion system (T6SS), an effector delivery pathway that mediates interbacterial competition. Here we define the distribution and role of GA1-3 in the human gut using metagenomic analysis. We find that adult microbiomes harbor limited effector and cognate immunity genes, suggesting selection for compatibility at the species (GA1 and GA2) and strain (GA3) levels...
September 13, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28889297/contribution-of-cyclic-di-gmp-in-the-control-of-type-iii-and-type-vi-secretion-in-pseudomonas-aeruginosa
#2
Ronan R McCarthy, Martina Valentini, Alain Filloux
Bacteria produce toxins to enhance their competitiveness in the colonization of an environment as well as during an infection. The delivery of toxins into target cells is mediated by several types of secretion systems, among them our focus is Type III and Type VI Secretion Systems (T3SS and T6SS, respectively). A thorough methodology is provided detailing how to identify if cyclic di-GMP signaling plays a role in the P. aeruginosa toxin delivery mediated by T3SS or T6SS. This includes in vitro preparation of the samples for Western blot analysis aiming at detecting possible c-di-GMP-dependent T3SS/T6SS switch, as well as in vivo analysis using the model organism Galleria mellonella to demonstrate the ecological and pathogenic consequence of the switch between these two secretion systems...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28848712/burkholderia-pseudomallei-evades-nramp1-slc11a1-and-nadph-oxidase-mediated-killing-in-macrophages-and-exhibits-nramp1-dependent-virulence-gene-expression
#3
Veerachat Muangsombut, Patoo Withatanung, Varintip Srinon, Narisara Chantratita, Mark P Stevens, Jenefer M Blackwell, Sunee Korbsrisate
Bacterial survival in macrophages can be affected by the natural resistance-associated macrophage protein 1 (Nramp1; also known as solute carrier family 11 member a1 or Slc11a1) which localizes to phagosome membranes and transports divalent cations, including iron. Little is known about the role of Nramp1 in Burkholderia infection, in particular whether this differs for pathogenic species like Burkholderia pseudomallei causing melioidosis or non-pathogenic species like Burkholderia thailandensis. Here we show that transfected macrophages stably expressing wild-type Nramp1 (Nramp1(+)) control the net replication of B...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28847494/isolated-pseudomonas-aeruginosa-strain-vih2-and-antagonistic-properties-against-ralstonia-solanacearum
#4
Xincheng Ge, Wei Wei, Gen Li, Mingming Sun, Huixin Li, Jun Wu, Feng Hu
The aim of this study was to isolates with antagonist activity against R. solanacearum. Thirty-two bacterial isolates were obtained from samples, and they were screened for potential antagonistic activity against R. Solanacearum. Using the agar spot method, ten out of the 21 tested bacteria showed antilisterial activity. VIH2 had the highest inhibitory effect on the growth of R. Solanacearum. Based on 16S rDNA and Biolog test analysis, the strain VIH2 was identified as Pseudomonas aeruginosa. Single-factor and Response Surface Methodology experiments were used to optimize the culture medium and conditions...
August 25, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28830939/a-transcriptional-regulatory-mechanism-finely-tunes-the-firing-of-type-vi-secretion-system-in-response-to-bacterial-enemies
#5
Martina Lazzaro, Mario F Feldman, Eleonora García Véscovi
The ability to detect and measure danger from an environmental signal is paramount for bacteria to respond accordingly, deploying strategies that halt or counteract potential cellular injury and maximize survival chances. Type VI secretion systems (T6SSs) are complex bacterial contractile nanomachines able to target toxic effectors into neighboring bacteria competing for the same colonization niche. Previous studies support the concept that either T6SSs are constitutively active or they fire effectors in response to various stimuli, such as high bacterial density, cell-cell contact, nutrient depletion, or components from dead sibling cells...
August 22, 2017: MBio
https://www.readbyqxmd.com/read/28818949/in-situ-architecture-function-and-evolution-of-a-contractile-injection-system
#6
Désirée Böck, João M Medeiros, Han-Fei Tsao, Thomas Penz, Gregor L Weiss, Karin Aistleitner, Matthias Horn, Martin Pilhofer
Contractile injection systems mediate bacterial cell-cell interactions by a bacteriophage tail-like structure. In contrast to extracellular systems, the type 6 secretion system (T6SS) is defined by intracellular localization and attachment to the cytoplasmic membrane. Here we used cryo-focused ion beam milling, electron cryotomography, and functional assays to study a T6SS in Amoebophilus asiaticus The in situ architecture revealed three modules, including a contractile sheath-tube, a baseplate, and an anchor...
August 18, 2017: Science
https://www.readbyqxmd.com/read/28818038/role-of-the-type-vi-secretion-systems-during-disease-interactions-of-erwinia-amylovora-with-its-plant-host
#7
Tim Kamber, Joël F Pothier, Cosima Pelludat, Fabio Rezzonico, Brion Duffy, Theo H M Smits
BACKGROUND: Type VI secretion systems (T6SS) are widespread among Gram-negative bacteria and have a potential role as essential virulence factors or to maintain symbiotic interactions. Three T6SS gene clusters were identified in the genome of E. amylovora CFBP 1430, of which T6SS-1 and T6SS-3 represent complete T6SS machineries, while T6SS-2 is reduced in its gene content. RESULTS: To assess the contribution of T6SSs to virulence and potential transcriptomic changes of E...
August 17, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28817192/tssa-the-cap-protein-of-the-type-vi-secretion-system-tail
#8
REVIEW
Abdelrahim Zoued, Eric Durand, Yoann G Santin, Laure Journet, Alain Roussel, Christian Cambillau, Eric Cascales
The Type VI secretion system (T6SS) is a multiprotein and mosaic apparatus that delivers protein effectors into prokaryotic or eukaryotic cells. Recent data on the enteroaggregative Escherichia coli (EAEC) T6SS have provided evidence that the TssA protein is a key component during T6SS biogenesis. The T6SS comprises a trans-envelope complex that docks the baseplate, a cytoplasmic complex that represents the assembly platform for the tail. The T6SS tail is structurally, evolutionarily and functionally similar to the contractile tails of bacteriophages...
August 17, 2017: BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology
https://www.readbyqxmd.com/read/28808000/vibrio-cholerae-type-6-secretion-system-effector-trafficking-in-target-bacterial-cells
#9
Brian T Ho, Yang Fu, Tao G Dong, John J Mekalanos
The type 6 secretion system (T6SS) is used by many Gram-negative bacterial species to deliver toxic effector proteins into nearby bacteria prey cells to kill or inhibit their growth. VgrG proteins are core conserved secretion substrates of the T6SS and one subset of T6SS effectors consists of VgrG proteins with C-terminal extension domains carrying various enzymatic activities. In Vibrio cholerae, VgrG3 has a hydrolase extension domain and degrades peptidoglycan in the periplasm of target bacteria. In this study, we replaced this domain with a nuclease domain from Salmonella enterica subsp...
August 29, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28804481/the-type-vi-secretion-system-a-dynamic-system-for-bacterial-communication
#10
REVIEW
Mathias Gallique, Mathilde Bouteiller, Annabelle Merieau
Numerous studies in Gram-negative bacteria have focused on the Type VI Secretion Systems (T6SSs), Quorum Sensing (QS), and social behavior, such as in biofilms. These interconnected mechanisms are important for bacterial survival; T6SSs allow bacteria to battle other cells, QS is devoted to the perception of bacterial cell density, and biofilm formation is essentially controlled by QS. Here, we review data concerning T6SS dynamics and T6SS-QS cross-talk that suggest the existence of inter-bacterial communication via T6SSs...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28777089/crystal-structure-of-the-putative-cytoplasmic-protein-stm0279-hcp2-from-salmonella-typhimurium
#11
Qing Peng Lin, Zeng Qiang Gao, Zhi Geng, Heng Zhang, Yu Hui Dong
STM0279 is a putative cytoplasmic protein from Salmonella typhimurium and was recently renamed haemolysin co-regulated protein 2 (Hcp2), with the neighbouring STM0276 being Hcp1. Both of them are encoded by the type VI secretion system (T6SS) of the Salmonella pathogenicity island 6 (SPI-6) locus and have high sequence identity. The Hcp proteins may function as a vital component of the T6SS nanotube and as a transporter and chaperone of diverse effectors from the bacterial T6SS. In this study, the crystal structure and the oligomeric state in solution of Hcp2 from S...
August 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/28760929/entry-intracellular-survival-and-multinucleated-giant-cell-forming-activity-of-burkholderia-pseudomallei-in-human-primary-phagocytic-and-non-phagocytic-cells
#12
Liam Whiteley, Teresa Meffert, Maria Haug, Christopher Weidenmaier, Verena Hopf, Katharina Bitschar, Birgit Schittek, Christian Kohler, Ivo Steinmetz, T Eoin West, Sandra Schwarz
The human pathogen Burkholderia pseudomallei and the related species Burkholderia thailandensis are facultative intracellular bacteria characterized by the ability to escape into the cytosol of the host cell and to stimulate the formation of multinucleated giant cells (MNGCs). MNGC formation is induced via an unknown mechanism by the bacterial type VI secretion system 5 (T6SS-5), which is an essential virulence factor in both species. Despite the vital role of the intracellular life cycle in the pathogenesis of the bacteria, the range of host cell types permissive for initiation and completion of the intracellular cycle is poorly defined...
July 31, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28758353/structural-and-saxs-analysis-of-tle5-tli5-complex-reveals-a-novel-inhibition-mechanism-of-h2-t6ss-in-pseudomonas-aeruginosa
#13
Xiao-Yun Yang, Zong-Qiang Li, Zeng-Qiang Gao, Wen-Jia Wang, Zhi Geng, Jian-Hua Xu, Zhun She, Yu-Hui Dong
Widely spread in gram-negative bacteria, the type VI secretion system (T6SS) secretes many effector-immunity protein pairs to help the bacteria compete against other prokaryotic rivals, and infect their eukaryotic hosts. Tle5 and Tle5B are two phospholipase effector protein secreted by T6SS of Pseudomonas aeruginosa. They can facilitate the bacterial internalization process into human epithelial cells by interacting with Akt protein of the PI3K-Akt signal pathway. Tli5 and PA5086-5088 are cognate immunity proteins of Tle5 and Tle5B, respectively...
July 30, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28746878/the-type-vi-secretion-system-engages-a-redox-regulated-dual-functional-heme-transporter-for-zinc-acquisition
#14
Meiru Si, Yao Wang, Bing Zhang, Chao Zhao, Yiwen Kang, Haonan Bai, Dawei Wei, Lingfang Zhu, Lei Zhang, Tao G Dong, Xihui Shen
The type VI secretion system was recently reported to be involved in zinc acquisition, but the underlying mechanism remains unclear. Here, we report that Burkholderia thailandensis T6SS4 is involved in zinc acquisition via secretion of a zinc-scavenging protein, TseZ, that interacts with the outer membrane heme transporter HmuR. We find that HmuR is a redox-regulated dual-functional transporter that transports heme iron under normal conditions but zinc upon sensing extracellular oxidative stress, triggered by formation of an intramolecular disulfide bond...
July 25, 2017: Cell Reports
https://www.readbyqxmd.com/read/28743812/horizontal-gene-transfer-of-functional-type-vi-killing-genes-by-natural-transformation
#15
Jacob Thomas, Samit S Watve, William C Ratcliff, Brian K Hammer
Horizontal gene transfer (HGT) can have profound effects on bacterial evolution by allowing individuals to rapidly acquire adaptive traits that shape their strategies for competition. One strategy for intermicrobial antagonism often used by Proteobacteria is the genetically encoded contact-dependent type VI secretion system (T6SS), a weapon used to kill heteroclonal neighbors by direct injection of toxic effectors. Here, we experimentally demonstrate that Vibrio cholerae can acquire new T6SS effector genes via horizontal transfer and utilize them to kill neighboring cells...
July 25, 2017: MBio
https://www.readbyqxmd.com/read/28715501/diversity-and-distribution-of-nuclease-bacteriocins-in-bacterial-genomes-revealed-using-hidden-markov-models
#16
Connor Sharp, James Bray, Nicholas G Housden, Martin C J Maiden, Colin Kleanthous
Bacteria exploit an arsenal of antimicrobial peptides and proteins to compete with each other. Three main competition systems have been described: type six secretion systems (T6SS); contact dependent inhibition (CDI); and bacteriocins. Unlike T6SS and CDI systems, bacteriocins do not require contact between bacteria but are diffusible toxins released into the environment. Identified almost a century ago, our understanding of bacteriocin distribution and prevalence in bacterial populations remains poor. In the case of protein bacteriocins, this is because of high levels of sequence diversity and difficulties in distinguishing their killing domains from those of other competition systems...
July 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28703218/the-type-vi-secretion-system-sheath-assembles-at-the-end-distal-from-the-membrane-anchor
#17
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/28673999/rsma-and-amrz-orchestrate-the-assembly-of-all-three-type-vi-secretion-systems-in-pseudomonas-aeruginosa
#18
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 18, 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
#19
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/28667630/screening-for-secretion-of-the-type-vi-secretion-system-protein-hcp-by-enzyme-linked-immunosorbent-assay-and-colony-blot
#20
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
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