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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
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
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
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
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
Feng Jiang, Xia Wang, Bei Wang, Lihong Chen, Zhendong Zhao, Nicholas R Waterfield, Guowei Yang, Qi Jin
Pseudomonas aeruginosa is an opportunistic pathogen that regularly causes nosocomial infections in hospitalized patients. The type VI secretion system (T6SS) is responsible for the secretion of numerous virulence effector proteins that can both interfere with competing microbes and manipulate host cells. Here, we report a detailed investigation of a P. aeruginosa H2-T6SS-dependent phospholipase effector, TplE, which acts as a trans-kingdom toxin. Delivery of TplE to the periplasmic space of rival bacteria leads to growth inhibition...
August 9, 2016: Cell Reports
Mateja Ozanic, Valentina Marecic, Marie Lindgren, Anders Sjöstedt, Marina Santic
Several bacterial pathogens interact with their host through protein secretion effectuated by a type VI secretion system (T6SS). Francisella tularensis is a highly pathogenic intracellular bacterium that causes the disease tularemia. Proteins encoded by the Francisella pathogenicity island (FPI), which constitute a type VI secretion system, are essential for the virulence of the bacterium and a key mechanism behind this is the escape from the phagosome followed by productive cytosolic replication. It has been shown that T6SS in Francisella is distinct since all putative substrates of F...
July 29, 2016: Microbes and Infection
Thibault G Sana, Benjamin Berni, Sophie Bleves
Pseudomonas aeruginosa is an opportunistic pathogen responsible for many diseases such as chronic lung colonization in cystic fibrosis patients and acute infections in hospitals. The capacity of P. aeruginosa to be pathogenic toward several hosts is notably due to different secretion systems. Amongst them, P. aeruginosa encodes three Type Six Secretion Systems (T6SS), named H1- to H3-T6SS, that act against either prokaryotes and/or eukaryotic cells. They are independent from each other and inject diverse toxins that interact with different components in the host cell...
2016: Frontiers in Cellular and Infection Microbiology
Francesca R Cianfanelli, Juliana Alcoforado Diniz, Manman Guo, Virginia De Cesare, Matthias Trost, Sarah J Coulthurst
The Type VI secretion system (T6SS) is widespread among bacterial pathogens and acts as an effective weapon against competitor bacteria and eukaryotic hosts by delivering toxic effector proteins directly into target cells. The T6SS utilises a bacteriophage-like contractile machinery to expel a puncturing device based on a tube of Hcp topped with a VgrG spike, which can be extended by a final tip from a PAAR domain-containing protein. Effector proteins are believed to be delivered by specifically associating with particular Hcp, VgrG or PAAR proteins, either covalently ('specialised') or non-covalently ('cargo' effectors)...
June 2016: PLoS Pathogens
Rosa van Mansfeld, Mark de Been, Fernanda Paganelli, Lei Yang, Marc Bonten, Rob Willems
This study investigates adaptation of ST406, a prevalent P. aeruginosa clone, present in 15% of chronically infected cystic fibrosis (CF) patients in the Netherlands, in a newly infected CF patient during three years using whole genome sequencing (WGS), transcriptomics, and phenotypic assays, including biofilm formation. WGS-based phylogeny demonstrates that ST406 is genetically distinct from other reported CF related strains or epidemic clones. Comparative genomic analysis of the early (S1) and late (S2) isolate yielded 42 single nucleotide polymorphisms (SNPs) and 10 indels and a single 7 kb genomic fragment only found in S2...
2016: PloS One
Devanand D Bondage, Jer-Sheng Lin, Lay-Sun Ma, Chih-Horng Kuo, Erh-Min Lai
Type VI secretion system (T6SS) is a macromolecular machine used by many Gram-negative bacteria to inject effectors/toxins into eukaryotic hosts or prokaryotic competitors for survival and fitness. To date, our knowledge of the molecular determinants and mechanisms underlying the transport of these effectors remains limited. Here, we report that two T6SS encoded valine-glycine repeat protein G (VgrG) paralogs in Agrobacterium tumefaciens C58 specifically control the secretion and interbacterial competition activity of the type VI DNase toxins Tde1 and Tde2...
July 5, 2016: Proceedings of the National Academy of Sciences of the United States of America
Mike Wilton, Megan J Q Wong, Le Tang, Xiaoye Liang, Richard Moore, Michael D Parkins, Shawn Lewenza, Tao G Dong
Pseudomonas aeruginosa employs its type VI secretion system (T6SS) as a highly effective and tightly regulated weapon to deliver toxic molecules to target cells. T6SS-secreted proteins of P. aeruginosa can be detected in the sputum of cystic fibrosis (CF) patients, who typically present a chronic and polymicrobial lung infection. However, the mechanism of T6SS activation in the CF lung is not fully understood. Here we demonstrate that extracellular DNA (eDNA), abundant within the CF airways, stimulates the dynamics of the H1-T6SS cluster apparatus in Pseudomonas aeruginosa PAO1...
August 2016: Infection and Immunity
Ying Peng, Xiangru Wang, Jin Shou, Bingbing Zong, Yanyan Zhang, Jia Tan, Jing Chen, Linlin Hu, Yongwei Zhu, Huanchun Chen, Chen Tan
Hcp (hemolysin-coregulated protein) is considered a vital component of the functional T6SS (Type VI Secretion System), which is a newly discovered secretion system. Our laboratory has previously sequenced the whole genome of porcine extraintestinal pathogenic E. coli (ExPEC) strain PCN033, and identified an integrated T6SS encoding three different hcp family genes. In this study, we first identified a functional T6SS in porcine ExPEC strain PCN033, and demonstrated that the Hcp family proteins were involved in bacterial competition and the interactions with other cells...
2016: Scientific Reports
Christopher J Alteri, Harry L T Mobley
Bacterial type VI secretion systems (T6SSs) function as contractile nanomachines to puncture target cells and deliver lethal effectors. In the 10 years since the discovery of the T6SS, much has been learned about the structure and function of this versatile protein secretion apparatus. Most of the conserved protein components that comprise the T6SS apparatus itself have been identified and ascribed specific functions. In addition, numerous effector proteins that are translocated by the T6SS have been identified and characterized...
April 2016: Microbiology Spectrum
Laure Journet, Eric Cascales
The type VI secretion system (T6SS) is a multiprotein complex widespread in Proteobacteria and dedicated to the delivery of toxins into both prokaryotic and eukaryotic cells. It thus participates in interbacterial competition as well as pathogenesis. The T6SS is a contractile weapon, related to the injection apparatus of contractile tailed bacteriophages. Basically, it assembles an inner tube wrapped by a sheath-like structure and anchored to the cell envelope via a membrane complex. The energy released by the contraction of the sheath propels the inner tube through the membrane channel and toward the target cell...
May 2016: EcoSal Plus
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