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Type VI secretion

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https://www.readbyqxmd.com/read/29674124/diverse-toxic-effectors-are-harbored-by-vgrg-islands-for-interbacterial-antagonism-in-type-vi-secretion-system
#1
Jiale Ma, Min Sun, Zihao Pan, Chengping Lu, Huochun Yao
The type VI secretion system (T6SS) is considered as one of the key competition strategies by injecting toxic effectors for intestinal pathogens to acquire optimal colonization in host gut, a microenviroment with high-density polymicrobial community where bacteria compete for niches and resources. Enterotoxigenic Escherichia coli (ETEC), a major cause of infectious diarrhea in human and animals, widely encode T6SS clusters in their genomes. In this report, we first identified VT1, a novel amidase effector in ETEC, significantly hydrolyzed D-lactyl-L-Ala crosslinks between N-acetylmuramoyl and L-Ala in peptidoglycan...
April 16, 2018: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/29610339/the-vibrio-cholerae-type-vi-secretion-system-can-modulate-host-intestinal-mechanics-to-displace-gut-bacterial-symbionts
#2
Savannah L Logan, Jacob Thomas, Jinyuan Yan, Ryan P Baker, Drew S Shields, Joao B Xavier, Brian K Hammer, Raghuveer Parthasarathy
Host-associated microbiota help defend against bacterial pathogens; however, the mechanisms by which pathogens overcome this defense remain largely unknown. We developed a zebrafish model and used live imaging to directly study how the human pathogen Vibrio cholerae invades the intestine. The gut microbiota of fish monocolonized by symbiotic strain Aeromonas veronii was displaced by V. cholerae expressing its type VI secretion system (T6SS), a syringe-like apparatus that deploys effector proteins into target cells...
April 2, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29599293/tagf-mediated-repression-of-bacterial-type-vi-secretion-systems-involves-a-direct-interaction-with-the-cytoplasmic-protein-fha
#3
Jer-Sheng Lin, Panayiota Pissaridou, Hsin-Hui Wu, Ming-Daw Tsai, Alain Filloux, Erh-Min Lai
The bacterial type VI secretion system (T6SS) delivers effectors into eukaryotic host cells or toxins into bacterial competitor for survival and fitness. The T6SS is positively regulated by the threonine phosphorylation pathway (TPP) and negatively by the T6SS-accessory protein TagF. Here, we studied the mechanisms underlying TagF-mediated T6SS repression in two distinct bacterial pathogens, Agrobacterium tumefaciens and Pseudomonas aeruginosa. We found that in A. tumefaciens, T6SS toxin secretion and T6SS-dependent antibacterial activity are suppressed by a two-domain chimeric protein consisting of TagF and PppA, a putative phosphatase...
March 29, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29593238/three-hcp-homologs-with-divergent-extended-loop-regions-exhibit-different-functions-in-avian-pathogenic-escherichia-coli
#4
Jiale Ma, Min Sun, Zihao Pan, Wenchao Song, Chengping Lu, Huochun Yao
Type VI secretion systems (T6SSs) contribute to the pathogenicity of avian pathogenic Escherichia coli (APEC), one of the leading causative agents of sepsis and meningitis in poultry. The Hcp protein is a core component of the T6SS tail tube and acts as an exported receptor and a chaperone of effectors. In this study, four distinct Hcp types (Ia, Ib, IIa, and IIb) were designated in Gram-negative bacteria, three of which were widely distributed in APEC. We detected divergence in transcription levels among three hcp clusters in 50% duck serum and demonstrated that hcp1 was upregulated by relieving Fur repression...
March 29, 2018: Emerging Microbes & Infections
https://www.readbyqxmd.com/read/29580623/phosphorylation-of-pppa-at-threonine-253-controls-t6ss2-expression-and-bacterial-killing-capacity-in-the-marine-pathogen-vibrio-alginolyticus
#5
Zhen Yang, Xuetong Wang, Wensheng Xu, Mian Zhou, Yuanxing Zhang, Yue Ma, Qiyao Wang
Type VI secretion systems (T6SSs) are multi-protein secretory nano-machines that mediate inter-bacterial competition. Vibrio alginolyticus is an abundant gram-negative marine bacterium that efficiently kills other bacteria with its T6SS2. The V. alginolyticus T6SS2 gene cluster encodes a phosphatase, PppA, and a type II membrane-spanning Hanks-type threonine kinase, PpkA2, which have been implicated in the activation of T6S. Meanwhile, T6SS2 gene expression is under the control of quorum sensing. However, the role of PppA in T6SS2 activity is unclear...
April 2018: Microbiological Research
https://www.readbyqxmd.com/read/29555704/t6ss-dynamics-reveals-a-novel-secretion-mechanism-in-pseudomonas-aeruginosa
#6
Jacqueline Corbitt, Jun Seok Yeo, C Ian Davis, Michele LeRoux, Paul A Wiggins
The Type VI Secretion System (T6SS) inhibits growth of neighboring bacterial cells through a contact-mediated mechanism. We describe a detailed characterization of the protein localization dynamics in the Pseudomonas aeruginosa T6SS. It has been proposed that Type VI secretion process is driven by a conformational-change induced contraction of the T6SS sheath. However, although the contraction of an optically resolvable TssBC sheath and the subsequent localization of ClpV are observed in Vibrio cholerae , coordinated assembly and disassembly of TssB and ClpV are observed without TssB contraction in P...
March 19, 2018: Journal of Bacteriology
https://www.readbyqxmd.com/read/29555703/a-proposed-chaperone-of-the-bacterial-type-vi-secretion-system-functions-to-constrain-a-self-identity-protein
#7
Martha A Zepeda-Rivera, Christina C Saak, Karine A Gibbs
The bacterium Proteus mirabilis can communicate identity through the secretion of the self-identity protein, IdsD, via the type VI secretion (T6S) system. IdsD secretion is essential for self versus non-self recognition behaviors in these populations. Here we provide an answer to the unresolved question of how the activity of a T6S substrate, such as IdsD, is regulated before secretion. We demonstrate that IdsD is found in clusters that form independently of the T6S machinery and activity. We show that the protein IdsC, which is a member of the proposed DUF4123 chaperone family, is essential for the maintenance of these clusters as well as the IdsD protein itself...
March 19, 2018: Journal of Bacteriology
https://www.readbyqxmd.com/read/29552635/isolation-and-identification-of-proteins-secreted-by-cells-cultured-within-synthetic-hydrogel-based-matrices
#8
Lisa A Sawicki, Leila H Choe, Katherine L Wiley, Kelvin H Lee, April M Kloxin
Cells interact with and remodel their microenvironment, degrading large extracellular matrix (ECM) proteins (e.g., fibronectin, collagens) and secreting new ECM proteins and small soluble factors (e.g., growth factors, cytokines). Synthetic mimics of the ECM have been developed as controlled cell culture platforms for use in both fundamental and applied studies. However, how cells broadly remodel these initially well-defined matrices remains poorly understood and difficult to probe. In this work, we have established methods for widely examining both large and small proteins that are secreted by cells within synthetic matrices...
March 12, 2018: ACS Biomaterials Science & Engineering
https://www.readbyqxmd.com/read/29547915/bastion6-a-bioinformatics-approach-for-accurate-prediction-of-type-vi-secreted-effectors
#9
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
https://www.readbyqxmd.com/read/29524318/whole-genome-sequence-and-phenotypic-characterization-of-a-cbm-serotype-e-strain-of-streptococcus-mutans
#10
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
https://www.readbyqxmd.com/read/29522749/protein-injection-machines-in-bacteria
#11
REVIEW
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
https://www.readbyqxmd.com/read/29521546/collagen-type-vi-interaction-improves-human-islet-survival-in-immunoisolating-microcapsules-for-treatment-of-diabetes
#12
L Alberto Llacua, Arjan Hoek, Bart J de Haan, Paul de Vos
Collagens are the most abundant fibrous protein in the human body and constitute the main structural element of the extracellular matrix. It provides mechanical and physiological support for cells. In the pancreas, collagen VI content is more than double that of collagen I or IV. It is a major component of the islet-exocrine interface and could be involved in islet-cell survival. To test the impact of collagen VI on human encapsulated pancreatic islets-cells, we tested the effects of exogenous collagen type VI on in vitro functional survival of alginate encapsulated human islet-cells...
March 9, 2018: Islets
https://www.readbyqxmd.com/read/29516754/functional-exploration-of-the-bacterial-type-vi-secretion-system-in-mutualism-azorhizobium-caulinodans-ors571-sesbania-rostrata-as-a-research-model
#13
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
https://www.readbyqxmd.com/read/29515200/mechanism-of-the-escherichia-coli-mlte-lytic-transglycosylase-the-cell-wall-penetrating-enzyme-for-type-vi-secretion-system-assembly
#14
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
https://www.readbyqxmd.com/read/29508143/the-role-of-the-immune-cells-in-fracture-healing
#15
REVIEW
Gurpreet S Baht, Linda Vi, Benjamin A Alman
PURPOSE OF REVIEW: Bone fracture healing is a complex physiological process relying on numerous cell types and signals. Inflammatory factors secreted by immune cells help to control recruitment, proliferation, differentiation, and activation of hematopoietic and mesenchymal cells. Within this review we will discuss the functional role of immune cells as it pertains to bone fracture healing. In doing so, we will outline the cytokines secreted and their effects within the healing fracture callus...
March 5, 2018: Current Osteoporosis Reports
https://www.readbyqxmd.com/read/29503811/systematic-identification-of-intracellular-translocated-candidate-effectors-in-edwardsiella-piscicida
#16
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
https://www.readbyqxmd.com/read/29467721/a-microfluidics-and-agent-based-modeling-framework-for-investigating-spatial-organization-in-bacterial-colonies-the-case-of-pseudomonas-aeruginosa-and-h1-type-vi-secretion-interactions
#17
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
https://www.readbyqxmd.com/read/29459733/conditional-toxicity-and-synergy-drive-diversity-among-antibacterial-effectors
#18
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
https://www.readbyqxmd.com/read/29458124/tryptophan-mediated-dimerization-of-the-tssl-transmembrane-anchor-is-required-for-type-vi-secretion-system-activity
#19
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
https://www.readbyqxmd.com/read/29452951/antibacterial-weapons-targeted-destruction-in-the-microbiota
#20
REVIEW
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
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