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Bacteria secretion system

Maarten G K Ghequire, Toon Swings, Jan Michiels, Susan K Buchanan, René De Mot
Lectin-like bacteriocins (LlpAs) are secreted by proteobacteria and selectively kill strains of their own or related species, and they are composed of two B-lectin domains with divergent sequences. In Pseudomonas spp., initial binding of these antibacterial proteins to cells is mediated by the carboxy-terminal domain through d-rhamnose residues present in the common polysaccharide antigen of their lipopolysaccharide, whereas the amino-terminal domain accounts for strain selectivity of killing. Here, we show that spontaneous LlpA-resistant mutants carry mutations in one of three surface-exposed moieties of the essential β-barrel outer membrane protein insertase BamA, the core component of the BAM complex...
March 20, 2018: MBio
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
Netra P Meena, Alan R Kimmel
Initial immunological defense mechanisms to pathogen invasion rely on innate pathways of chemotaxis and phagocytosis, original to ancient phagocytes. Although chemotaxis has been well-studied in mammalian and model systems using purified chemoattractants in defined conditions, directed movement toward live bacteria has been more difficult to assess. Dictyostelium discoideum is a professional phagocyte that chemotaxes toward bacteria during growth-phase in a process to locate nutrient sources. Using Dictyostelium as a model, we have developed a system that is able to quantify chemotaxis to very high sensitivity...
2018: Frontiers in Cellular and Infection Microbiology
A Leoni Swart, Christopher F Harrison, Ludwig Eichinger, Michael Steinert, Hubert Hilbi
Environmental bacteria of the genus Legionella naturally parasitize free-living amoebae. Upon inhalation of bacteria-laden aerosols, the opportunistic pathogens grow intracellularly in alveolar macrophages and can cause a life-threatening pneumonia termed Legionnaires' disease. Intracellular replication in amoebae and macrophages takes place in a unique membrane-bound compartment, the Legionella -containing vacuole (LCV). LCV formation requires the bacterial Icm/Dot type IV secretion system, which translocates literally hundreds of "effector" proteins into host cells, where they modulate crucial cellular processes for the pathogen's benefit...
2018: Frontiers in Cellular and Infection Microbiology
Chengchao Ding, Junfei Ma, Qingli Dong, Qing Liu
Live bacteria, including attenuated bacteria and probiotics, can be engineered to deliver target antigen to excite the host immune system. The preponderance of these live bacterial vaccine vectors is that they can stimulate durable humoral and cellular immunity. Moreover, delivery strategies of heterologous antigen in live bacterial promote the applications of new vaccine development. Genetic technologies are evolving, which potentiate the developing of heterologous antigen delivery systems, including bacterial surface display system, bacterial secretion system and balanced lethal vector system...
March 14, 2018: Immunology Letters
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
Guirong Tang, Qiong Li, Shenghui Xing, Ningning Li, Zheng Tang, Liangliang Yu, Junhui Yan, Xuan Li, Li Luo
Agrobacterium tumefaciens infects and causes crown galls in dicot plants by transferring T-DNA from the Ti plasmid to the host plant via a type IV secretion system (T4SS). This process requires appropriate environmental conditions, certain plant secretions and bacterial regulators. In our previous work, a member of the LysR family of transcriptional regulators (LsrB) in Sinorhizobium meliloti was found to modulate its symbiotic interactions with the host plant alfalfa. However, the function of its homologue in A...
March 16, 2018: Molecular Plant-microbe Interactions: MPMI
BoYoon Chang, BongSeong Koo, HyeonCheol Lee, Joa Sub Oh, SungYeon Kim
Background: The innate immune system plays a crucial role in the initiation and subsequent direction of adaptive immune responses, as well as in the removal of pathogens that have been targeted by an adaptive immune response. Objective: Morus alba L. was reported to have immunostimulatory properties that might protect against infectious diseases. However, this possibility has not yet been explored. The present study investigated the protective and immune-enhancing ability of M...
2018: Food & Nutrition Research
Konstantinos C Tsolis, Evridiki-Pandora Tsare, Georgia Orfanoudaki, Tobias Busche, Katerina Kanaki, Reshmi Ramakrishnan, Frederic Rousseau, Joost Schymkowitz, Christian Rückert, Jörn Kalinowski, Jozef Anné, Spyridoula Karamanou, Maria I Klapa, Anastassios Economou
BACKGROUND: Members of the genus Streptomyces are Gram-positive bacteria that are used as important cell factories to produce secondary metabolites and secrete heterologous proteins. They possess some of the largest bacterial genomes and thus proteomes. Understanding their complex proteomes and metabolic regulation will improve any genetic engineering approach. RESULTS: Here, we performed a comprehensive annotation of the subcellular localization of the proteome of Streptomyces lividans TK24 and developed the Subcellular Topology of Polypeptides in Streptomyces database (SToPSdb) to make this information widely accessible...
March 15, 2018: Microbial Cell Factories
Glenn T Werneburg, David G Thanassi
Gram-negative bacteria assemble a variety of surface structures, including the hair-like organelles known as pili or fimbriae. Pili typically function in adhesion and mediate interactions with various surfaces, with other bacteria, and with other types of cells such as host cells. The chaperone/usher (CU) pathway assembles a widespread class of adhesive and virulence-associated pili. Pilus biogenesis by the CU pathway requires a dedicated periplasmic chaperone and integral outer membrane protein termed the usher, which forms a multifunctional assembly and secretion platform...
March 2018: EcoSal Plus
Claudia C Paredes-Amaya, Gilberto Valdés-García, Víctor R Juárez-González, Enrique Rudiño-Piñera, Víctor H Bustamante
HilD is an AraC-like transcriptional regulator that plays a central role in Salmonella virulence. HilD controls the expression of the genes within the Salmonella pathogenicity island 1 (SPI-1) and of several genes located outside SPI-1, which are mainly required for Salmonella invasion of host cells. The expression, amount and activity of HilD are tightly controlled by the activities of several factors. The HilE protein represses the expression of the SPI-1 genes through its interaction with HilD; however, the mechanism by which HilE affects HilD is unknown...
March 13, 2018: Journal of Biological Chemistry
Federico Sabbadin, Giovanna Pesante, Luisa Elias, Katrin Besser, Yi Li, Clare Steele-King, Meg Stark, Deborah A Rathbone, Adam A Dowle, Rachel Bates, J Reuben Shipway, Simon M Cragg, Neil C Bruce, Simon J McQueen-Mason
Lignocellulose forms the structural framework of woody plant biomass and represents the most abundant carbon source in the biosphere. Turnover of woody biomass is a critical component of the global carbon cycle, and the enzymes involved are of increasing industrial importance as industry moves away from fossil fuels to renewable carbon resources. Shipworms are marine bivalve molluscs that digest wood and play a key role in global carbon cycling by processing plant biomass in the oceans. Previous studies suggest that wood digestion in shipworms is dominated by enzymes produced by endosymbiotic bacteria found in the animal's gills, while little is known about the identity and function of endogenous enzymes produced by shipworms...
2018: Biotechnology for Biofuels
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
Maozhi Hu, Weixin Zhao, Hongying Li, Jie Gu, Qiuxiang Yan, Xiaohui Zhou, Zhiming Pan, Guiyou Cui, Xinan Jiao
BACKGROUND: Enhancing caspase-1 activation in macrophages is helpful for the clearance of intracellular bacteria in mice. Our previous studies have shown that EscI, an inner rod protein of type III system in E. coli can enhance caspase-1 activation. The purpose of this study was to further analyze the prospect of EscI in the vaccine design. RESULTS: A recombinant Salmonella expressing SspH2-EscI fusion protein using the promotor of Salmonella effector SspH2, X4550(pYA3334-P-SspH2-EscI), was constructed...
March 9, 2018: BMC Veterinary Research
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
L T Sigle, J F Hillyer
Haemocytes respond to infection by phagocytosing pathogens, producing the enzymes that drive the phenoloxidase-based melanization cascade, secreting lytic factors, and producing other humoral proteins. A subset of haemocytes, called periostial haemocytes, aggregate on the surface of the heart of mosquitoes and kill pathogens in areas of high haemolymph flow. Periostial haemocytes are always present, but an infection induces the recruitment of additional haemocytes to these regions. Here, we tested whether members of the Nimrod gene family are involved in the periostial immune response of the African malaria mosquito, Anopheles gambiae...
March 9, 2018: Insect Molecular Biology
Roberto Ferro, Maja Rennig, Cristina Hernández-Rollán, Daniel O Daley, Morten H H Nørholm
BACKGROUND: The market for recombinant proteins is on the rise, and Gram-positive strains are widely exploited for this purpose. Bacillus subtilis is a profitable host for protein production thanks to its ability to secrete large amounts of proteins, and Lactococcus lactis is an attractive production organism with a long history in food fermentation. RESULTS: We have developed a synbio approach for increasing gene expression in two Gram-positive bacteria. First of all, the gene of interest was coupled to an antibiotic resistance gene to create a growth-based selection system...
March 8, 2018: Microbial Cell Factories
Victoria Hritonenko, Matteo Metruccio, David Evans, Suzanne Fleiszig
The type three secretion system (T3SS) is important for the intracellular survival of Pseudomonas aeruginosa. Known T3SS inducers include low Ca2+, serum, or host cell contact. Here, we used corneal epithelial cell lysates to test if host cytosolic factors could also induce the T3SS. Invasive P. aeruginosa strain PAO1 was exposed to cell lysates for 16 h, and expression of T3SS effectors determined by q-PCR and Western immunoblot. Lysate exposure reduced PAO1 growth (∼5-fold) versus trypticase soy broth (TSB), but also resulted in appearance of a protein in culture supernatants, but not bacteria cell pellets, that reacted with antibody raised against ExoS...
March 6, 2018: FEMS Microbiology Letters
Jinhong Kan, Lin An, Yao Wu, Jia Long, Liyang Song, Rongxiang Fang, Yantao Jia
During plant-pathogen interactions, pathogenic bacteria have evolved multiple strategies to cope with the sophisticated defense systems of host plants. Proline iminopeptidase (PIP) is essential to Xanthomonas campestris pv. campestris (Xcc) virulence, and conserved in many plant-associated bacteria, but its pathogenic mechanism remains unclear. In this study, we found that disrupting pip in Xcc enhanced its flagella-mediated bacterial motility by decreasing intracellular c-di-GMP levels, and overexpression of pip restricted bacterial motility by elevating c-di-GMP levels...
March 8, 2018: Molecular Plant Pathology
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
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