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Type VI secretion

Christian Adam, Jonas Wohlfarth, Maike Haußmann, Helga Sennefelder, Annette Rodin, Mareike Maler, Stefan F Martin, Matthias Goebeler, Marc Schmidt
Chromium allergy is a common occupational skin disease mediated by chromium (VI)-specific T cells that induce delayed-type hypersensitivity in sensitized individuals. Additionally, chromium (VI) can act as irritant. Both responses critically require innate immune activation, but if and how chromium (VI) elicits this signal is currently unclear.Using human monocytes, primary human keratinocytes and murine dendritic cells we show that chromium (VI) compounds fail to trigger direct proinflammatory activation but potently induce processing and secretion of IL-1β...
October 14, 2016: Journal of Investigative Dermatology
Brent S Weber, Seth W Hennon, Meredith S Wright, Nichollas E Scott, Véronique de Berardinis, Leonard J Foster, Juan A Ayala, Mark D Adams, Mario F Feldman
: The type VI secretion system (T6SS) is a widespread secretory apparatus produced by Gram-negative bacteria that has emerged as a potent mediator of antibacterial activity during interbacterial interactions. Most Acinetobacter species produce a genetically conserved T6SS, although the expression and functionality of this system vary among different strains. Some pathogenic Acinetobacter baumannii strains activate this secretion system via the spontaneous loss of a plasmid carrying T6SS repressors...
October 11, 2016: MBio
Badreddine Douzi, Yannick R Brunet, Silvia Spinelli, Valentine Lensi, Pierre Legrand, Stéphanie Blangy, Anant Kumar, Laure Journet, Eric Cascales, Christian Cambillau
The Type VI secretion system (T6SS) is a versatile machine that delivers toxins into either eukaryotic or bacterial cells. It thus represents a key player in bacterial pathogenesis and inter-bacterial competition. Schematically, the T6SS can be viewed as a contractile tail structure anchored to the cell envelope. The contraction of the tail sheath propels the inner tube loaded with effectors towards the target cell. The components of the contracted tail sheath are then recycled by the ClpV AAA(+) ATPase for a new cycle of tail elongation...
October 4, 2016: Scientific Reports
Daya Marasini, Mohamed K Fakhr
Genome sequences of Campylobacter jejuni strains OD267 and WP2202, isolated from chicken livers and gizzards, showed the presence of novel 116-kb and 119-kb megaplasmids, respectively. The two megaplasmids carry a type VI secretion system and tetracycline resistance genes. These are the largest sequenced Campylobacter plasmids to date.
September 29, 2016: Genome Announcements
Andrei Fokine, Michael G Rossmann
Many large viruses, including tailed dsDNA bacteriophages and herpesviruses, assemble their capsids via formation of precursors, called procapsids or proheads. The prohead has an internal core, made of scaffolding proteins, and an outer shell, formed by the major capsid protein. The prohead usually contains a protease, which is activated during capsid maturation to destroy the inner core and liberate space for the genome. Here, we report a 2.0 Å resolution structure of the pentameric procapsid protease of bacteriophage T4, gene product (gp)21...
September 20, 2016: Structure
Megan Wong, Xiaoye Liang, Matt Smart, Le Tang, Richard Moore, Brian Ingalls, Tao G Dong
: In the host and natural environments, microbes often exist in complex multispecies communities. The molecular mechanisms through which such communities develop and persist - despite significant antagonistic interactions between species - are not well understood. The type VI secretion system (T6SS) is a lethal weapon commonly employed by Gram-negative bacteria to inhibit neighboring species through delivery of toxic effectors. It is well established that intra-species protection is conferred by immunity proteins that neutralize effector toxicities...
September 16, 2016: Applied and Environmental Microbiology
Afreenish Hassan, Anam Naz, Ayesha Obaid, Rehan Zafar Paracha, Kanwal Naz, Faryal Mehwish Awan, Syed Aun Muhmmad, Hussnain Ahmed Janjua, Jamil Ahmad, Amjad Ali
BACKGROUND: Acinetobacter baumannii has emerged as a significant nosocomial pathogen during the last few years, exhibiting resistance to almost all major classes of antibiotics. Alternative treatment options such as vaccines tend to be most promising and cost effective approaches against this resistant pathogen. In the current study, we have explored the pan-genome of A. baumannii followed by immune-proteomics and reverse vaccinology approaches to identify potential core vaccine targets...
2016: BMC Genomics
Andrea Vettiger, Marek Basler
Bacterial type VI secretion system (T6SS) is a nanomachine that works similarly to a speargun. Rapid contraction of a sling (sheath) drives a long shaft (Hcp) with a sharp tip and associated effectors through the target cell membrane. We show that the amount and composition of the tip regulates initiation of full-length sheath assembly and low amount of available Hcp decreases sheath length. Importantly, we show that both tip and Hcp are exchanged by T6SS among by-standing cells within minutes of initial cell-cell contact...
September 22, 2016: Cell
Fang Liu, Jinlong Li, Guofang Feng, Zhiyong Li
"Entotheonella" (phylum "Tectomicrobia") is a filamentous symbiont that produces almost all known bioactive compounds derived from the Lithistida sponge Theonella swinhoei. In contrast to the comprehensive knowledge of its secondary metabolism, knowledge of its lifestyle, resilience, and interaction with the sponge host and other symbionts remains rudimentary. In this study, we obtained two "Entotheonella" genomes from T. swinhoei from the South China Sea through metagenome binning, and used a RASTtk pipeline to achieve better genome annotation...
2016: Frontiers in Microbiology
Wen-Jen Chen, Tzu-Yen Kuo, Feng-Chia Hsieh, Pi-Yu Chen, Chang-Sheng Wang, Yu-Ling Shih, Ying-Mi Lai, Je-Ruei Liu, Yu-Liang Yang, Ming-Che Shih
Rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most destructive rice diseases worldwide. Therefore, in addition to breeding disease-resistant rice cultivars, it is desirable to develop effective biocontrol agents against Xoo. Here, we report that a soil bacterium Pseudomonas taiwanensis displayed strong antagonistic activity against Xoo. Using matrix-assisted laser desorption/ionization imaging mass spectrometry, we identified an iron chelator, pyoverdine, secreted by P. taiwanensis that could inhibit the growth of Xoo...
2016: Scientific Reports
Mélanie Rigard, Jeanette E Bröms, Amandine Mosnier, Maggy Hologne, Amandine Martin, Lena Lindgren, Claire Punginelli, Claire Lays, Olivier Walker, Alain Charbit, Philippe Telouk, Wayne Conlan, Laurent Terradot, Anders Sjöstedt, Thomas Henry
The virulence of Francisella tularensis, the etiological agent of tularemia, relies on an atypical type VI secretion system (T6SS) encoded by a genomic island termed the Francisella Pathogenicity Island (FPI). While the importance of the FPI in F. tularensis virulence is clearly established, the precise role of most of the FPI-encoded proteins remains to be deciphered. In this study, using highly virulent F. tularensis strains and the closely related species F. novicida, IglG was characterized as a protein featuring a unique α-helical N-terminal extension and a domain of unknown function (DUF4280), present in more than 250 bacterial species...
September 2016: PLoS Pathogens
Sebastián Riquelme, Macarena Varas, Camila Valenzuela, Paula Velozo, Nicolás Chahin, Paulina Aguilera, Andrea Sabag, Bayron Labra, Sergio A Álvarez, Francisco P Chávez, Carlos A Santiviago
The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In this work, D. discoideum was used as a model to study the ability of Salmonella Typhimurium to survive in amoebae and to evaluate the contribution of selected genes in this process. To do this, we performed infection assays using axenic cultures of D. discoideum co-cultured with wild-type S. Typhimurium and/or defined mutant strains. Our results confirmed that wild-type S...
2016: Frontiers in Microbiology
Laureen Logger, Marie-Stéphanie Aschtgen, Marie Guérin, Eric Cascales, Eric Durand
The type VI secretion system (T6SS) is a multi-protein complex that catalyses toxin secretion through the bacterial cell envelope of various Gram-negative bacteria including important human pathogens. This machine uses a bacteriophage-like contractile tail to puncture the prey cell and inject armful toxins. The T6SS tail comprises an inner tube capped by the cell-puncturing spike and wrapped by the contractile sheath. This structure is built on an assembly platform, the baseplate, which is anchored to the bacterial cell envelope by the TssJLM membrane complex...
September 3, 2016: Journal of Molecular Biology
Abdelrahim Zoued, Chloé J Cassaro, Eric Durand, Badreddine Douzi, Alexandre P España, Christian Cambillau, Laure Journet, Eric Cascales
The Type VI secretion system (T6SS) is a multiprotein complex that delivers toxin effectors in both prokaryotic and eukaryotic cells. It is constituted of a long cytoplasmic structure - the tail - made of stacked Hcp hexamers and wrapped by a contractile sheath. Contraction of the sheath propels the inner tube capped by the VgrG spike protein towards the target cell. This tubular structure is built onto an assembly platform - the baseplate - that is composed of the TssEFGK-VgrG subunits. During the assembly process, the baseplate is recruited to a trans-envelope complex comprising the TssJ outer membrane lipoprotein and the TssL and TssM inner membrane proteins...
September 3, 2016: Journal of Molecular Biology
Glenn S Belinsky, Leanne Ward, Chuhan Chung
Osteogenesis imperfecta (OI) Type VI is characterized by a defect in bone mineralization, which results in multiple fractures early in life. Null mutations in the PEDF gene, Serpinf1, are the cause of OI VI. Whether PEDF restoration in a murine model of OI Type VI could improve bone mass and function was previously unknown. In Belinsky et al, we provided evidence that PEDF delivery enhanced bone mass and improved parameters of bone function in vivo. Further, we demonstrated that PEDF temporally inhibits Wnt signaling to enhance osteoblast differentiation...
2016: Rare Diseases
Ermin Schadich, Petr Džubák, Marián Hajdúch
Virulence capsular polysaccharide (Vi antigen) and Salmonella`s Pathogenicity Island type 1 and 2 (SPI-1 and SPI-2 TTSS) are important membrane virulence factors of human restricted pathogen S. Typhi. The Vi antigen modulates different proinflammatory signaling pathways in infected macrophages, microfold epithelial and dendritic cells. SPI-2 TTSS and its effectors are required for promoting bacterial intracellular survival, replication and apoptosis while SPI-1 and its effectors are associated with invasion of microfold epithelial cells...
August 29, 2016: Current Pharmaceutical Design
Carina R Büttner, Yingzhou Wu, Karen L Maxwell, Alan R Davidson
Contractile phage tails are powerful cell puncturing nanomachines that have been co-opted by bacteria for self-defense against both bacteria and eukaryotic cells. The tail of phage T4 has long served as the paradigm for understanding contractile tail-like systems despite its greater complexity compared with other contractile-tailed phages. Here, we present a detailed investigation of the assembly of a "simple" contractile-tailed phage baseplate, that of Escherichia coli phage Mu. By coexpressing various combinations of putative Mu baseplate proteins, we defined the required components of this baseplate and delineated its assembly pathway...
September 6, 2016: Proceedings of the National Academy of Sciences of the United States of America
Sophie Bleves
TplE, a type VI secreted (phospho)lipase, has been identified as the third trans-kingdom effector of Pseudomonas aeruginosa, targeting both prokaryotic and eukaryotic hosts. Indeed, TplE triggers the killing of bacterial competitors and promotes autophagy in epithelial cells once localized to the endoplasmic reticulum.
October 2016: Trends in Microbiology
Koichi Ojima, Mika Oe, Ikuyo Nakajima, Susumu Muroya, Takanori Nishimura
The major functions of adipocytes include both lipid storage and the production of secretory factors. However, the type of proteins released from mouse 3T3-L1 cells during adipocyte differentiation remains poorly understood. We examined the dynamics of secreted proteins during adipocyte differentiation using mass spectrometry (MS) combined with an iTRAQ (®) labeling method that enables the simultaneous analysis of relative protein expression levels. A total of 215 proteins were identified and quantified from approximately 10 000 MS/MS spectra...
August 2016: FEBS Open Bio
Thibault G Sana, Nicolas Flaugnatti, Kyler A Lugo, Lilian H Lam, Amanda Jacobson, Virginie Baylot, Eric Durand, Laure Journet, Eric Cascales, Denise M Monack
The mammalian gastrointestinal tract is colonized by a high-density polymicrobial community where bacteria compete for niches and resources. One key competition strategy includes cell contact-dependent mechanisms of interbacterial antagonism, such as the type VI secretion system (T6SS), a multiprotein needle-like apparatus that injects effector proteins into prokaryotic and/or eukaryotic target cells. However, the contribution of T6SS antibacterial activity during pathogen invasion of the gut has not been demonstrated...
August 23, 2016: Proceedings of the National Academy of Sciences of the United States of America
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