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Type vi secretion system

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https://www.readbyqxmd.com/read/29326272/antagonism-toward-the-intestinal-microbiota-and-its-effect-on-vibrio-cholerae-virulence
#1
Wenjing Zhao, Florence Caro, William Robins, John J Mekalanos
The bacterial type VI secretion system (T6SS) is a nanomachine that delivers toxic effector proteins into target cells, killing them. In mice, we found that the Vibrio cholerae T6SS attacks members of the host commensal microbiota in vivo, facilitating the pathogen's colonization of the gut. This microbial antagonistic interaction drives measurable changes in the pathogenicity of V. cholerae through enhanced intestinal colonization, expression of bacterial virulence genes, and activation of host innate immune genes...
January 12, 2018: Science
https://www.readbyqxmd.com/read/29322563/microfluidics-based-lc-ms-mrm-approach-for-the-relative-quantification-of-burkholderia-cenocepacia-secreted-virulence-factors
#2
Sofie Depluverez, Simon Daled, Stijn De Waele, Sören Planckaert, Jolien Schoovaerts, Dieter Deforce, Bart Devreese
Burkholderia cenocepacia is an opportunistic pathogen that is commonly isolated from patients with cystic fibrosis (CF). Several virulence factors have been identified, including extracellular enzymes that are secreted by type II and type VI secretion systems. The activity of these secretion systems is modulated by quorum sensing. Apart from the classical acylhomoserine lactone quorum sensing, B. cenocepacia also uses the diffusible signal factor system (DSF) i.e. 2-undecenoic acid derivatives that are recognized by specific receptors resulting in changes in biofilm formation, motility and virulence...
January 11, 2018: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/29319806/comparative-genomics-highlights-symbiotic-capacities-and-high-metabolic-flexibility-of-the-marine-genus-pseudovibrio
#3
Dennis Versluis, Bart Nijsse, Mohd Azrul Naim, Jasper J Koehorst, Jutta Wiese, Johannes F Imhoff, Peter J Schaap, Mark W J van Passel, Hauke Smidt, Detmer Sipkema
Pseudovibrio is a marine bacterial genus members of which are predominantly isolated from sessile marine animals, and particularly sponges. It has been hypothesised that Pseudovibrio spp. form mutualistic relationships with their hosts. Here, we studied Pseudovibrio phylogeny and genetic adaptations that may play a role in host colonization by comparative genomics of 31 Pseudovibrio strains, including 25 sponge isolates. All genomes were highly similar in terms of encoded core metabolic pathways, albeit with substantial differences in overall gene content...
January 8, 2018: Genome Biology and Evolution
https://www.readbyqxmd.com/read/29317252/flavonoids-and-the-gastrointestinal-tract-local-and-systemic-effects
#4
REVIEW
P I Oteiza, C G Fraga, D A Mills, D H Taft
The gastrointestinal (GI) tract plays a central role in the absorption, distribution, metabolism, and excretion of flavonoids, which ultimately define the health effects of these bioactives. These aspects are modulated by the interactions of flavonoids with other dietary components, environmental factors, the host, and the GI microbiota. Flavonoid can target molecules in the luminal content, the different GI tract cell types, and the microbiota. Importantly, flavonoid actions at the GI tract can have an impact systemically, e...
January 6, 2018: Molecular Aspects of Medicine
https://www.readbyqxmd.com/read/29314727/molecular-processes-underlying-synergistic-linuron-mineralization-in-a-triple-species-bacterial-consortium-biofilm-revealed-by-differential-transcriptomics
#5
Pieter Albers, Bram Weytjens, René De Mot, Kathleen Marchal, Dirk Springael
The proteobacteria Variovorax sp. WDL1, Comamonas testosteroni WDL7, and Hyphomicrobium sulfonivorans WDL6 compose a triple-species consortium that synergistically degrades and grows on the phenylurea herbicide linuron. To acquire a better insight into the interactions between the consortium members and the underlying molecular mechanisms, we compared the transcriptomes of the key biodegrading strains WDL7 and WDL1 grown as biofilms in either isolation or consortium conditions by differential RNAseq analysis...
January 3, 2018: MicrobiologyOpen
https://www.readbyqxmd.com/read/29314726/the-complete-genome-sequence-of-vibrio-aestuarianus-w-40-reveals-virulence-factor-genes
#6
Xiaojin Xu, Lixing Huang, Yongquan Su, Qingpi Yan
Vibrio aestuarianus is an opportunistic environmental pathogen that has been associated with epidemics in cultured shrimp Penaeus vannamei. Hepatopancreas microsporidian (HPM) and monodon slow growth syndrome (MSGS) have been reported in cultured P. vannamei. In this study, we sequenced and assembled the whole genome of V. aestuarianus strain W-40, a strain that was originally isolated from the intestines of an infected P. vannamei. The genome of V. aestuarianus strain W-40 contains two circular chromosomes of 483,7307 bp with a 46...
January 3, 2018: MicrobiologyOpen
https://www.readbyqxmd.com/read/29314504/serine-threonine-kinase-ppka-coordinates-the-interplay-between-t6ss2-activation-and-quorum-sensing-in-the-marine-pathogen-vibrio-alginolyticus
#7
Zhen Yang, Xiaohui Zhou, Yue Ma, Mian Zhou, Matthew K Waldor, Yuanxing Zhang, Qiyao Wang
Type VI secretion systems (T6SS) are multiprotein secretion machines that can mediate killing of bacterial cells and thereby modify the composition of bacterial communities. The mechanisms that control the production of and secretion of these killing machines are incompletely understood, although quorum sensing (QS) and the PpkA kinase modulate T6SS activity in some organisms. Here we investigated control the T6S in the marine organism Vibrio alginolyticus EPGS, which encodes two T6SS systems (T6SS1 and T6SS2)...
January 4, 2018: Environmental Microbiology
https://www.readbyqxmd.com/read/29309434/mucin-acts-as-a-nutrient-source-and-a-signal-for-the-differential-expression-of-genes-coding-for-cellular-processes-and-virulence-factors-in-acinetobacter-baumannii
#8
Emily J Ohneck, Brock A Arivett, Steven E Fiester, Cecily R Wood, Maeva L Metz, Gabriella M Simeone, Luis A Actis
The capacity of Acinetobacter baumannii to persist and cause infections depends on its interaction with abiotic and biotic surfaces, including those found on medical devices and host mucosal surfaces. However, the extracellular stimuli affecting these interactions are poorly understood. Based on our previous observations, we hypothesized that mucin, a glycoprotein secreted by lung epithelial cells, particularly during respiratory infections, significantly alters A. baumannii's physiology and its interaction with the surrounding environment...
2018: PloS One
https://www.readbyqxmd.com/read/29307484/atomic-structure-of-type-vi-contractile-sheath-from-pseudomonas-aeruginosa
#9
Osman Salih, Shaoda He, Sara Planamente, Lasse Stach, James T MacDonald, Eleni Manoli, Sjors H W Scheres, Alain Filloux, Paul S Freemont
Pseudomonas aeruginosa has three type VI secretion systems (T6SSs), H1-, H2-, and H3-T6SS, each belonging to a distinct group. The two T6SS components, TssB/VipA and TssC/VipB, assemble to form tubules that conserve structural/functional homology with tail sheaths of contractile bacteriophages and pyocins. Here, we used cryoelectron microscopy to solve the structure of the H1-T6SS P. aeruginosa TssB1C1 sheath at 3.3 Å resolution. Our structure allowed us to resolve some features of the T6SS sheath that were not resolved in the Vibrio cholerae VipAB and Francisella tularensis IglAB structures...
December 21, 2017: Structure
https://www.readbyqxmd.com/read/29307074/genetically-encoded-photochemical-covalent-crosslinking-within-the-hcp-1-self-assembling-bacterial-secretion-machinery
#10
Alicja K Antonczak, Kedric Milholland, Eric M Tippmann
The target protein, Hcp1, was first described as part of the bacterial Type VI secretion system from Pseudomonas aeruginosa. The protein first self-assembles into a hexamer and then the hexamers further stack into a nanotubular structure. Hcp1 monomers were targeted for mutagenesis with two widely used photoactivatable amino acids: para-benzoyl phenylalanine or para-azidophenylalanine. The ability of these amino acids to form covalent adducts within the Hcp1 self-assembled system was investigated. Multiple residues, putatively of equal distance between the monomer-monomer interface were targeted...
January 6, 2018: Amino Acids
https://www.readbyqxmd.com/read/29281838/the-role-of-type-vi-secretion-system-effectors-in-target-cell-lysis-and-subsequent-horizontal-gene-transfer
#11
Peter David Ringel, Di Hu, Marek Basler
Bacteria use type VI secretion systems (T6SSs) to manipulate host cells during pathogenesis or to kill competing bacteria, which, in some cases, increases horizontal gene transfer. These functions largely depend on T6SS regulation, dynamics, and the set of effectors that the system delivers into the target cells. Here, we show that Acinetobacter baylyi ADP1 assembles a highly dynamic T6SS capable of killing and lysing bacterial cells. T6SS function depends on conserved T6SS components as well as Acinetobacter-specific genes of unknown function...
December 26, 2017: Cell Reports
https://www.readbyqxmd.com/read/29237732/diverse-nadase-effector-families-mediate-interbacterial-antagonism-via-the-type-vi-secretion-system
#12
Jenny Y Tang, Nathan P Bullen, Shehryar Ahmad, John C Whitney
The bacterial type VI secretion system (T6SS) mediates antagonistic cell-cell interactions between competing Gram-negative bacteria. In plant-beneficial bacteria, this pathway has been shown to suppress the growth of bacterial pathogens; however, the identification and mode of action of T6SS effector proteins that mediate this protective effect remain poorly defined. Here, we identify two previously uncharacterized effectors required for interbacterial antagonism by the plant commensal bacterium Pseudomonas protegens...
December 13, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29233893/diversification-of-type-vi-secretion-system-toxins-reveals-ancient-antagonism-among-bee-gut-microbes
#13
Margaret I Steele, Waldan K Kwong, Marvin Whiteley, Nancy A Moran
Microbial communities are shaped by interactions among their constituent members. Some Gram-negative bacteria employ type VI secretion systems (T6SSs) to inject protein toxins into neighboring cells. These interactions have been theorized to affect the composition of host-associated microbiomes, but the role of T6SSs in the evolution of gut communities is not well understood. We report the discovery of two T6SSs and numerous T6SS-associated Rhs toxins within the gut bacteria of honey bees and bumble bees. We sequenced the genomes of 28 strains of Snodgrassella alvi, a characteristic bee gut microbe, and found tremendous variability in their Rhs toxin complements: altogether, these strains appear to encode hundreds of unique toxins...
December 12, 2017: MBio
https://www.readbyqxmd.com/read/29230364/complete-genome-sequence-and-comparative-genomics-of-the-golden-pompano-trachinotus-ovatus-pathogen-vibrio-harveyi-strain-qt520
#14
Zhigang Tu, Hongyue Li, Xiang Zhang, Yun Sun, Yongcan Zhou
Vibrio harveyi is a Gram-negative, halophilic bacterium that is an opportunistic pathogen of commercially farmed marine vertebrate species. To understand the pathogenicity of this species, the genome of V. harveyi QT520 was analyzed and compared to that of other strains. The results showed the genome of QT520 has two unique circular chromosomes and three endogenous plasmids, totaling 6,070,846 bp with a 45% GC content, 5,701 predicted ORFs, 134 tRNAs and 37 rRNAs. Common virulence factors, including ACF, IlpA, OmpU, Flagellin, Cya, Hemolysin and MARTX, were detected in the genome, which are likely responsible for the virulence of QT520...
2017: PeerJ
https://www.readbyqxmd.com/read/29223729/structure-function-analysis-of-the-c-terminal-domain-of-the-type-vi-secretion-tssb-tail-sheath-subunit
#15
Badreddine Douzi, Laureen Logger, Silvia Spinelli, Stéphanie Blangy, Christian Cambillau, Eric Cascales
The Type VI secretion system (T6SS) is a specialized macromolecular complex dedicated to the delivery of protein effectors into both eukaryotic and bacterial cells. The general mechanism of action of the T6SS is similar to the injection of DNA by contractile bacteriophages. The cytoplasmic portion of the T6SS is evolutionarily, structurally and functionally related to the phage tail complex. It is composed of an inner tube made of stacked Hcp hexameric rings, engulfed within a sheath and built on a baseplate...
December 6, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/29222345/type-vi-secretion-system-sheath-inter-subunit-interactions-modulate-its-contraction
#16
Maximilian Brackmann, Jing Wang, Marek Basler
Secretion systems are essential for bacteria to survive and manipulate their environment. The bacterial type VI secretion system (T6SS) generates the force needed for protein translocation by the contraction of a long polymer called sheath. The sheath is a six-start helical assembly of interconnected VipA/VipB subunits. The mechanism of T6SS sheath contraction is unknown. Here, we show that elongating the N-terminal VipA linker or eliminating charge of a specific VipB residue abolishes sheath contraction and delivery of effectors into target cells...
December 8, 2017: EMBO Reports
https://www.readbyqxmd.com/read/29216271/genomic-and-phenotypic-characteristics-of-swedish-c-jejuni-water-isolates
#17
Anna Nilsson, Cecilia Johansson, Astrid Skarp, René Kaden, Lars Engstrand, Hilpi Rautelin
Campylobacter jejuni is the most common cause of bacterial gastroenteritis. Major reservoirs are warm-blooded animals, poultry in particular, but Campylobacter can also be transmitted via water. In this paper, we have taken a closer look at the biology and potential virulence of C. jejuni water isolates. Seven C. jejuni isolates from incoming surface water at water plants in Sweden were characterized with whole genome sequencing and phenotypical testing. Multi locus sequence typing analysis revealed that these isolates belonged to groups known to include both common (ST48CC) and uncommon (ST1275CC, ST683, ST793 and ST8853) human pathogens...
2017: PloS One
https://www.readbyqxmd.com/read/29209037/bacteriophage-t5-tail-tube-structure-suggests-a-trigger-mechanism-for-siphoviridae-dna-ejection
#18
Charles-Adrien Arnaud, Grégory Effantin, Corinne Vivès, Sylvain Engilberge, Maria Bacia, Pascale Boulanger, Eric Girard, Guy Schoehn, Cécile Breyton
The vast majority of phages, bacterial viruses, possess a tail ensuring host recognition, cell wall perforation and safe viral DNA transfer from the capsid to the host cytoplasm. Long flexible tails are formed from the tail tube protein (TTP) polymerised as hexameric rings around and stacked along the tape measure protein (TMP). Here, we report the crystal structure of T5 TTP pb6 at 2.2 Å resolution. Pb6 is unusual in forming a trimeric ring, although structure analysis reveals homology with all classical TTPs and related tube proteins of bacterial puncturing devices (type VI secretion system and R-pyocin)...
December 5, 2017: Nature Communications
https://www.readbyqxmd.com/read/29184542/lysogenic-conversion-of-the-phytopathogen-ralstonia-solanacearum-by-the-p2virus-%C3%AF-rsy1
#19
Ahmed Askora, Takeru Kawasaki, Makoto Fujie, Takashi Yamada
A P2-like phage ϕRSY1 infecting the phytopathogen Ralstonia solanacearum was isolated and characterized. The 40-kb genome of ϕRSY1 showed high sequence similarity to the Ralstonia phage ϕRSA1 and the GMI1000 prophage ϕRSX. The major genomic differences between these phages were the different orientation of the int gene and the gene content close to the cosL. ϕRSY1 and ϕRSX use a 15-base 3' portion of the serine tRNA(GGA) gene as attB, while ϕRSA1 uses a 45-base 3' portion of the arginine tRNA(CCG) gene...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29184019/gut-symbiont-bacteroides-fragilis-secretes-a-eukaryotic-like-ubiquitin-protein-that-mediates-intraspecies-antagonism
#20
Maria Chatzidaki-Livanis, Michael J Coyne, Kevin G Roelofs, Rahul R Gentyala, Jarreth M Caldwell, Laurie E Comstock
Human gut Bacteroides species produce different types of toxins that antagonize closely related members of the gut microbiota. Some are toxic effectors delivered by type VI secretion systems, and others are non-contact-dependent secreted antimicrobial proteins. Many strains of Bacteroides fragilis secrete antimicrobial molecules, but only one of these toxins has been described to date (Bacteroidales secreted antimicrobial protein 1 [BSAP-1]). In this study, we describe a novel secreted protein produced by B...
November 28, 2017: MBio
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