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Type vi secretion system

Jiawei Wang, Bingjiao Yang, André Leier, Tatiana T Marquez-Lago, Morihiro Hayashida, Andrea Rocker, Zhang Yanju, Tatsuya Akutsu, Kuo-Chen Chou, Richard A Strugnell, Jiangning Song, Trevor Lithgow
Motivation: Many Gram-negative bacteria use type VI secretion systems (T6SS) to export effector proteins into adjacent target cells. These secreted effectors (T6SEs) play vital roles in the competitive survival in bacterial populations, as well as pathogenesis of bacteria. Although various computational analyses have been previously applied to identify effectors secreted by certain bacterial species, there is no universal method available to accurately predict T6SS effector proteins from the growing tide of bacterial genome sequence data...
March 14, 2018: Bioinformatics
Alejandro Avilés-Reyes, Irlan Almeida Freires, Jessica K Kajfasz, Dicler Barbieri, James H Miller, José A Lemos, Jacqueline Abranches
We report the whole genome sequence (WGS) of the serotype e Cbm+ strain LAR01 of Streptococcus mutans, a dental pathogen frequently associated with extra-oral infections. The LAR01 genome is a single circular chromosome of 2.1 Mb with a GC content of 36.96%. The genome contains 15 PTS gene clusters, 7 cell wall-anchored (LPxTG) proteins, all genes required for the development of natural competence and genes coding for mutacins VI and K8. Interestingly, the cbm gene is genetically linked to a putative type VII secretion system that has been found in Mycobacteria and few other gram-positive bacteria...
March 9, 2018: Molecular Oral Microbiology
Jorge E Galán, Gabriel Waksman
Many bacteria have evolved specialized nanomachines with the remarkable ability to inject multiple bacterially encoded effector proteins into eukaryotic or prokaryotic cells. Known as type III, type IV, and type VI secretion systems, these machines play a central role in the pathogenic or symbiotic interactions between multiple bacteria and their eukaryotic hosts, or in the establishment of bacterial communities in a diversity of environments. Here we focus on recent progress elucidating the structure and assembly pathways of these machines...
March 8, 2018: Cell
Hsiao-Han Lin, Hsin-Mei Huang, Manda Yu, Erh-Min Lai, Hsiao-Lin Chien, Chi-Te Liu
The bacterial type VI secretion system (T6SS) has been considered the armed force of bacteria because it can deliver toxin effectors to prokaryotic or eukaryotic cells for survival and fitness. Although many legume symbiotic rhizobacteria encode T6SS in their genome, the biological function of T6SS in these bacteria is still unclear. To elucidate this issue, we used Azorhizobium caulinodans ORS571 and its symbiotic host Sesbania rostrata as our research model. By using T6SS gene deletion mutants, we found that T6SS provides A...
March 8, 2018: Molecular Plant-microbe Interactions: MPMI
Byungjin Byun, Kiran V Mahasenan, David A Dik, Daniel R Marous, Enrico Speri, Malika Kumarasiri, Jed F Fisher, Juan A Hermoso, Shahriar Mobashery
Lytic transglycosylases (LTs) catalyze the non-hydrolytic cleavage of the bacterial cell wall by an intramolecular transacetalization reaction. This reaction is critically and broadly important in modifications of the bacterial cell wall in the course of its biosynthesis, recycling, manifestation of virulence, insertion of structural entities such as the flagellum and the pili, among others. The first QM/MM analysis of the mechanism of reaction of an LT, that for the Escherichia coli MltE, is undertaken. The study reveals a conformational itinerary consistent with an oxocarbenium-like transition state, characterized by a pivotal role for the active-site glutamic acid in proton transfer...
March 7, 2018: Scientific Reports
Lingzhi Zhang, Zhiwei Jiang, Shan Fang, Yajun Huang, Dahai Yang, Qiyao Wang, Yuanxing Zhang, Qin Liu
Many bacterial pathogens inject effectors directly into host cells to target a variety of host cellular processes and promote bacterial dissemination and survival. Identifying the bacterial effectors and elucidating their functions are central to understanding the molecular pathogenesis of these pathogens. Edwardsiella piscicida is a pathogen with a wide host range, and very few of its effectors have been identified to date. Here, based on the genes significantly regulated by macrophage infection, we identified 25 intracellular translocation-positive candidate effectors, including all five previously reported effectors, namely EseG, EseJ, EseH, EseK, and EvpP...
2018: Frontiers in Cellular and Infection Microbiology
Jared L Wilmoth, Peter W Doak, Andrea Timm, Michelle Halsted, John D Anderson, Marta Ginovart, Clara Prats, Xavier Portell, Scott T Retterer, Miguel Fuentes-Cabrera
The factors leading to changes in the organization of microbial assemblages at fine spatial scales are not well characterized or understood. However, they are expected to guide the succession of community development and function toward specific outcomes that could impact human health and the environment. In this study, we put forward a combined experimental and agent-based modeling framework and use it to interpret unique spatial organization patterns of H1-Type VI secretion system (T6SS) mutants of P . aeruginosa under spatial confinement...
2018: Frontiers in Microbiology
Kaitlyn D LaCourse, S Brook Peterson, Hemantha D Kulasekara, Matthew C Radey, Jungyun Kim, Joseph D Mougous
Bacteria in polymicrobial habitats contend with a persistent barrage of competitors, often under rapidly changing environmental conditions1 . The direct antagonism of competitor cells is thus an important bacterial survival strategy2 . Towards this end, many bacterial species employ an arsenal of antimicrobial effectors with multiple activities; however, the benefits conferred by the simultaneous deployment of diverse toxins are unknown. Here we show that the multiple effectors delivered to competitor bacteria by the type VI secretion system (T6SS) of Pseudomonas aeruginosa display conditional efficacy and act synergistically...
February 19, 2018: Nature Microbiology
Abdelrahim Zoued, Jean-Pierre Duneau, Eric Durand, Alexandre P España, Laure Journet, Françoise Guerlesquin, Eric Cascales
The Type VI secretion system (T6SS) is a multiprotein complex used by bacteria to deliver effectors into target cells. The T6SS comprises a bacteriophage-like contractile tail structure anchored to the cell envelope by a membrane complex constituted of the TssJ outer membrane lipoprotein and the TssL and TssM inner membrane proteins. TssJ establishes contact with the periplasmic domain of TssM whereas the transmembrane segments of TssM and its cytoplasmic domain interact with TssL. TssL protrudes in the cytoplasm but is anchored by a C-terminal transmembrane helix (TMH)...
February 16, 2018: Journal of Molecular Biology
Benoit Chassaing, Eric Cascales
The intestinal microbiota plays an important role in health, particularly in promoting intestinal metabolic capacity and in maturing the immune system. The intestinal microbiota also mediates colonization resistance against pathogenic bacteria, hence protecting the host from infections. In addition, some bacterial pathogens deliver toxins that target phylogenetically related or distinct bacterial species in order to outcompete and establish within the microbiota. The most widely distributed weapons include bacteriocins, as well as contact-dependent growth inhibition and type VI secretion systems...
February 13, 2018: Trends in Microbiology
Benjamin Kostiuk, Daniel Unterweger, Daniele Provenzano, Stefan Pukatzki
Vibrio cholerae is a diverse species that inhabits a wide range of environments from copepods in brackish water to the intestines of humans. In order to remain competitive, V. cholerae uses the versatile type-VI secretion system (T6SS) to secrete anti-prokaryotic and anti-eukaryotic effectors. In addition to competing with other bacterial species, V. cholerae strains also compete with one another. Some strains are able to coexist, and are referred to as belonging to the same compatibility group. Challenged by diverse competitors in various environments, different V...
September 2017: International Microbiology: the Official Journal of the Spanish Society for Microbiology
Felipe Cava
In this monographic issue, we have the pleasure to present contributions from six of the leading laboratories at the forefront of Vibrio cholerae genetics, ecology and evolution, together with a brief tribute by Diego Romero to Doctor Jaime Ferrán y Clua, a pioneering Spanish bacteriologist who developed the first vaccine against this pathogen. V. cholerae is a free-living aquatic bacterium that interacts with and infects a variety of organisms. In humans it causes cholera, the deadly diarrhoea that was responsible for millions of deaths during seven pandemics since 1817, and still thousands every year...
September 2017: International Microbiology: the Official Journal of the Spanish Society for Microbiology
Vera Troselj, Anke Treuner-Lange, Lotte Søgaard-Andersen, Daniel Wall
A hallmark of social microorganisms is their ability to engage in complex and coordinated behaviors that depend on cooperative and synchronized actions among many cells. For instance, myxobacteria use an aggregation strategy to form multicellular, spore-filled fruiting bodies in response to starvation. One barrier to the synchronization process is physiological heterogeneity within clonal populations. How myxobacteria cope with these physiological differences is poorly understood. Here, we investigated the interactions between closely related but physiologically distinct Myxococcus xanthus populations...
February 6, 2018: MBio
Chelsie E Armbruster, Harry L T Mobley, Melanie M Pearson
Proteus mirabilis , a Gram-negative rod-shaped bacterium most noted for its swarming motility and urease activity, frequently causes catheter-associated urinary tract infections (CAUTIs) that are often polymicrobial. These infections may be accompanied by urolithiasis, the development of bladder or kidney stones due to alkalinization of urine from urease-catalyzed urea hydrolysis. Adherence of the bacterium to epithelial and catheter surfaces is mediated by 17 different fimbriae, most notably MR/P fimbriae...
February 2018: EcoSal Plus
Thao Thi Nguyen, Hyun-Hee Lee, Inmyoung Park, Young-Su Seo
Type VI secretion system (T6SS) has been discovered in a variety of gram-negative bacteria as a versatile weapon to stimulate the killing of eukaryotic cells or prokaryotic competitors. Type VI secretion effectors (T6SEs) are well known as key virulence factors for important pathogenic bacteria. In many Burkholderia species, T6SS has evolved as the most complicated secretion pathway with distinguished types to translocate diverse T6SEs, suggesting their essential roles in this genus. Here we attempted to detect and characterize T6SSs and potential T6SEs in target genomes of plant-associated and environmental Burkholderia species based on computational analyses...
February 2018: Plant Pathology Journal
Juvenal Lopez, Mario F Feldman
The type VI secretion system (T6SS) delivers toxic effectors between Gram-negative bacteria. Most antibacterial T6SS effectors are peptidoglycanases, nucleases, or lipases. In the current work, Tang et al. structurally and functionally characterize a novel family of NAD(P)+-hydrolyzing effectors (NADases), thus expanding the documented types of T6SS substrates. Bioinformatic identification of NADase family members putatively secreted by the bacteriolytic type VII secretion system (T7SS) of Gram-positive bacteria further points to NADases as a diverse and important class of effectors...
February 2, 2018: Journal of Biological Chemistry
Van Son Nguyen, Badreddine Douzi, Eric Durand, Alain Roussel, Eric Cascales, Christian Cambillau
The Type VI secretion system (T6SS) is a dynamic nanomachine present in many Gram-negative bacteria. Using a contraction mechanism similar to that of myophages, bacteriocins or anti-feeding prophages, it injects toxic effectors into both eukaryotic and prokaryotic cells. T6SS assembles three large ensembles: the trans-membrane complex (TMC), the baseplate and the tail. Recently, the tail structure has been elucidated by cryo electron microscopy (cryoEM) in extended and contracted forms. The structure of the trans-membrane complex has been deciphered using a combination of X-ray crystallography and EM...
February 1, 2018: Current Opinion in Structural Biology
Nicholas M I Taylor, Mark J van Raaij, Petr G Leiman
Contractile tail bacteriophages, or myobacteriophages, use a sophisticated biomolecular structure to inject their genome into the bacterial host cell. This structure consists of a contractile sheath enveloping a rigid tube that is sharpened by a spike-shaped protein complex at its tip. The spike complex forms the centerpiece of a baseplate complex that terminates the sheath and the tube. The baseplate anchors the tail to the target cell membrane with the help of fibrous proteins emanating from it and triggers contraction of the sheath...
February 5, 2018: Molecular Microbiology
Andrés Zalguizuri, Gustavo Caetano-Anollés, Viviana Claudia Lepek
In the establishment and maintenance of the interaction between pathogenic or symbiotic bacteria with a eukaryotic organism, protein substrates of specialized bacterial secretion systems called effectors play a critical role once translocated into the host cell. Proteins are also secreted to the extracellular medium by free-living bacteria or directly injected into other competing organisms to hinder or kill. In this work, we explore an approach based on the evolutionary dependence that most of the effectors maintain with their specific secretion system that analyzes the co-occurrence of any orthologous protein group and their corresponding secretion system across multiple genomes...
January 31, 2018: Briefings in Bioinformatics
Jianfeng Wang, Zhihui Zhou, Fang He, Zhi Ruan, Yan Jiang, Xiaoting Hua, Yunsong Yu
The Type VI Secretion System (T6SS) is an important virulence system that exists in many bacterial pathogens, and has emerged as a potent mediator of pathogenicity in Acinetobacter baumannii. In this study, we inactivated one of the T6SS components vgrG (valine-glycine repeat G) gene in A. baumannii ATCC 19606 and constructed a complementation strain. BEAS-2b human alveolar epithelial cells was adopted to assess bacterial adhesion, and wild female BALB/c mice were used for in vivo experiments to assess the bacterial killing ability to host...
2018: PloS One
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