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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
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
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
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
Ethel Bayer-Santos, Lidia Dos Passos Lima, Lucas de Moraes Ceseti, Camila Yuri Ratagami, Eliane Silva de Santana, Aline Maria da Silva, Chuck Shaker Farah, Cristina Elisa Alvarez-Martinez
Plant-associated bacteria of the genus Xanthomonas cause disease in a wide range of economically important crops. However, their ability to persist in the environment is still poorly understood. Predation by amoebas represent a major selective pressure to bacterial populations in the environment. In this study, we show that the X. citri type 6 secretion system (T6SS) promotes resistance to predation by the soil amoeba Dictyostelium discoideum. We found that an extracytoplasmic function (ECF) sigma factor (EcfK) is required for induction of T6SS genes during interaction with Dictyostelium...
February 28, 2018: Environmental Microbiology
Bin Li, Xiaoxuan Wang, Jie Chen, He Liu, Khattak Arif Ali, Yanli Wang, Wen Qiu, Guochang Sun
Acidovorax oryzae (Ao) cause bacterial brown stripe in rice that result in great economic loss. However, the pathogenic mechanism of this rice bacterial pathogen still remains unclear. Interestingly, transcriptomic and proteomic analysis of in vivo infection indicate that the pathogenicity of Ao strain RS-1 may be associated with the type six secretion system (T6SS), which was identified by in silico comparative genomic analysis in our previous studies. This makes it necessary to further examine the role of each core component of T6SS in the pathogenicity of Ao strain RS-1 to rice plants...
February 24, 2018: Archives of 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
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
Tomeu Viver, Luis Orellana, Pedro González-Torres, Sara Díaz, Mercedes Urdiain, María Eugenia Farías, Vladimir Benes, Peter Kaempfer, Azadeh Shahinpei, Mohammad Ali Amoozegar, Rudolf Amann, Josefa Antón, Konstantinos T Konstantinidis, Ramon Rosselló-Móra
The application of tandem MALDI-TOF MS screening with 16S rRNA gene sequencing of selected isolates has been demonstrated to be an excellent approach for retrieving novelty from large-scale culturing. The application of such methodologies in different hypersaline samples allowed the isolation of the culture-recalcitrant Salinibacter ruber second phylotype (EHB-2) for the first time, as well as a new species recently isolated from the Argentinian Altiplano hypersaline lakes. In this study, the genome sequences of the different species of the phylum Rhodothermaeota were compared and the genetic repertoire along the evolutionary gradient was analyzed together with each intraspecific variability...
January 31, 2018: Systematic and Applied Microbiology
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
Yang Fu, Brian T Ho, John J Mekalanos
Vibrio cholerae is the causative agent of the diarrheal disease cholera. Although many V. cholerae virulence factors have been studied, the role of interbacterial interactions within the host gut and their influence on colonization are poorly understood. Here, we utilized the conjugative properties of a Vibrio-specific plasmid to serve as a quantifiable genetic marker for direct contact among V. cholerae cells in the infant rabbit model for cholera. In conjunction, we also quantified contact-dependent type 6 secretion system (T6SS)-mediated killing of co-infecting V...
February 1, 2018: Cell Host & Microbe
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
Bryan Troxell
Bacteria interact with their host through protein secretion systems and surface structures. Pathogenic bacteria encode protein secretion systems that promote the invasion of the host's tissue, the evasion of the host's immune response, the thwarting microbial competitors, and ultimately survival within the host. For motile bacteria, the presence of extracellular flagella provides the host with a structural motif used for activation of the immune system. Within this issue of Virulence, the article "Identification of a novel gene in ROD9 island of Salmonella Enteritidis involved in the alteration of virulence-associated protein expression" describes the contribution of a gene, SEN1005, toward host-pathogen interaction...
January 30, 2018: Virulence
Giuseppina Mariano, Laura Monlezun, Sarah J Coulthurst
Incorporation of disulfide bonds into proteins can be critical for function or stability. In bacterial cells, the periplasmic enzyme DsbA is responsible for disulfide incorporation into many extra-cytoplasmic proteins. The type VI secretion system (T6SS) is a widely occurring nanomachine that delivers toxic effector proteins directly into rival bacterial cells, playing a key role in inter-bacterial competition. We report that two redundant DsbA proteins are required for virulence and for proper deployment of the T6SS in the opportunistic pathogen Serratia marcescens, with several T6SS components being subject to the action of DsbA in secreting cells...
January 16, 2018: Cell Reports
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