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Bacteria secretion system

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https://www.readbyqxmd.com/read/28533471/the-atypical-response-regulator-atvr-is-a-new-player-in-pseudomonas-aeruginosa-response-to-hypoxia-and-virulence
#1
Gilberto Hideo Kaihami, Leandro Carvalho Dantas Breda, José Roberto Fogaça de Almeida, Thays de Oliveira Pereira, Gianlucca Gonçalves Nicastro, Ana Laura Boechat, Sandro Rogério de Almeida, Regina Lúcia Baldini
Two-component systems are widespread in bacteria, allowing adaptation to environmental changes. The classical pathway is composed by a histidine kinase that phosphorylates an aspartate residue in the cognate response regulator (RR). RRs lacking the phosphorylable aspartate also occur, but their function and contribution during host-pathogen interaction are poorly characterized. AtvR (PA14_26570) is the only atypical response regulator with a DNA-binding domain in the opportunistic pathogen Pseudomonas aeruginosa Macrophage infection with the atvR mutant strain resulted in higher TNF-α secretion as well as increased bacterial clearance as compared to macrophages infected with the wild-type strain...
May 22, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28528707/molecular-transcriptional-and-functional-insights-into-duplicated-goose-type-lysozymes-from-sebastes-schlegelii-and-their-potential-immunological-role
#2
Jehanathan Nilojan, S D N K Bathige, Roopasingam Kugapreethan, W S Thulasitha, Bo-Hye Nam, Jehee Lee
Black rockfish (Sebastes schlegelii), an important aquaculture species in Korea, has been affected by bacterial diseases leading to a drastic decline in production. Goose-type lysozyme (LysG) is a key enzyme of the innate immune system to eradicate bacterial infections. In this study, two isoforms of LysG from black rockfish, designated as RfLysG1 and RfLysG2, have been identified and characterized at the molecular, transcriptional, and functional levels. The deduced amino acid sequences had the LysG family characteristics and exhibited conserved properties, including active residues and domains...
May 18, 2017: Fish & Shellfish Immunology
https://www.readbyqxmd.com/read/28522850/pseudomonas-aeruginosa-exolysin-promotes-bacterial-growth-in-lungs-alveolar-damage-and-bacterial-dissemination
#3
Stéphanie Bouillot, Patrick Munro, Benoit Gallet, Emeline Reboud, François Cretin, Guillaume Golovkine, Guy Schoehn, Ina Attrée, Emmanuel Lemichez, Philippe Huber
Exolysin (ExlA) is a recently-identified pore-forming toxin secreted by a subset of Pseudomonas aeruginosa strains identified worldwide and devoid of Type III secretion system (T3SS), a major virulence factor. Here, we characterized at the ultrastructural level the lesions caused by an ExlA-secreting strain, CLJ1, in mouse infected lungs. CLJ1 induced necrotic lesions in pneumocytes and endothelial cells, resulting in alveolo-vascular barrier breakdown. Ectopic expression of ExlA in an exlA-negative strain induced similar tissue injuries...
May 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28512090/the-vibrio-cholerae-vexgh-rnd-efflux-system-maintains-cellular-homeostasis-by-effluxing-vibriobactin
#4
Dillon E Kunkle, X Renee Bina, James E Bina
Resistance-nodulation-division (RND) superfamily efflux systems have been widely studied for their role in antibiotic resistance, but their native biological functions remain poorly understood. We previously showed that loss of RND-mediated efflux in Vibrio cholerae resulted in activation of the Cpx two-component regulatory system, which mediates adaptation to stress resulting from misfolded membrane proteins. Here, we investigated the mechanism linking RND-mediated efflux to the Cpx response. We performed transposon mutagenesis screening of RND-deficient V...
May 16, 2017: MBio
https://www.readbyqxmd.com/read/28509355/lon-protease-modulates-virulence-traits-in-erwinia-amylovora-by-directly-monitoring-major-regulators-and-indirectly-through-the-rcs-and-gac-csr-regulatory-systems
#5
Jae Hoon Lee, Veronica Ancona, Youfu Zhao
Lon, an ATP-dependent protease in bacteria, influences diverse cellular processes by degrading damaged, misfolded and short-lived regulatory proteins. In this study, we characterized the effects of lon mutation and determined the molecular mechanisms underlying Lon-mediated virulence regulation in Erwinia amylovora, an enterobacterial pathogen of apple. E. amylovora depends on the type III secretion system (T3SS) and the exopolysaccharide (EPS) amylovoran to cause disease. Our results showed that mutation of the lon gene led to overproduction of amylovoran, increased T3SS gene expression and non-motile phenotype...
May 16, 2017: Molecular Plant Pathology
https://www.readbyqxmd.com/read/28496159/a-comprehensive-guide-to-pilus-biogenesis-in-gram-negative-bacteria
#6
REVIEW
Manuela K Hospenthal, Tiago R D Costa, Gabriel Waksman
Pili are crucial virulence factors for many Gram-negative pathogens. These surface structures provide bacteria with a link to their external environments by enabling them to interact with, and attach to, host cells, other surfaces or each other, or by providing a conduit for secretion. Recent high-resolution structures of pilus filaments and the machineries that produce them, namely chaperone-usher pili, type IV pili, conjugative type IV secretion pili and type V pili, are beginning to explain some of the intriguing biological properties that pili exhibit, such as the ability of chaperone-usher pili and type IV pili to stretch in response to external forces...
May 12, 2017: Nature Reviews. Microbiology
https://www.readbyqxmd.com/read/28487429/rationally-designed-tlr4-ligands-for-vaccine-adjuvant-discovery
#7
Kelsey A Gregg, Erin Harberts, Francesca M Gardner, Mark R Pelletier, Corinne Cayatte, Li Yu, Michael P McCarthy, Jason D Marshall, Robert K Ernst
Adjuvant properties of bacterial cell wall components like MPLA (monophosphoryl lipid A) are well described and have gained FDA approval for use in vaccines such as Cervarix. MPLA is the product of chemically modified lipooligosaccharide (LOS), altered to diminish toxic proinflammatory effects while retaining adequate immunogenicity. Despite the virtually unlimited number of potential sources among bacterial strains, the number of useable compounds within this promising class of adjuvants are few. We have developed bacterial enzymatic combinatorial chemistry (BECC) as a method to generate rationally designed, functionally diverse lipid A...
May 9, 2017: MBio
https://www.readbyqxmd.com/read/28487352/in-vivo-structures-of-an-intact-type-vi-secretion-system-revealed-by-electron-cryotomography
#8
Yi-Wei Chang, Lee A Rettberg, Davi R Ortega, Grant J Jensen
The type VI secretion system (T6SS) is a versatile molecular weapon used by many bacteria against eukaryotic hosts or prokaryotic competitors. It consists of a cytoplasmic bacteriophage tail-like structure anchored in the bacterial cell envelope via a cytoplasmic baseplate and a periplasmic membrane complex. Rapid contraction of the sheath in the bacteriophage tail-like structure propels an inner tube/spike complex through the target cell envelope to deliver effectors. While structures of purified contracted sheath and purified membrane complex have been solved, because sheaths contract upon cell lysis and purification, no structure is available for the extended sheath...
May 9, 2017: EMBO Reports
https://www.readbyqxmd.com/read/28486768/the-trans-envelope-architecture-and-function-of-the-type-2-secretion-system-new-insights-raising-new-questions
#9
REVIEW
Jenny-Lee Thomassin, Javier Santos Moreno, Ingrid Guilvout, Guy Tran Van Nhieu, Olivera Francetic
Nanomachines belonging to the type IV filament (Tff) superfamily serve a variety of cellular functions in prokaryotes, including motility, adhesion, electrical conductance, competence and secretion. The type 2 secretion system (T2SS) Tff member assembles a short filament called pseudopilus that promotes the secretion of folded proteins from the periplasm across the outer membrane of Gram-negative bacteria. A combination of structural, biochemical, imaging, computational and in vivo approaches had led to a working model for the assembled nanomachine...
May 9, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28485369/control-of-type-iii-protein-secretion-using-a-minimal-genetic-system
#10
Miryoung Song, David J Sukovich, Luciano Ciccarelli, Julia Mayr, Jesus Fernandez-Rodriguez, Ethan A Mirsky, Alex C Tucker, D Benjamin Gordon, Thomas C Marlovits, Christopher A Voigt
Gram-negative bacteria secrete proteins using a type III secretion system (T3SS), which functions as a needle-like molecular machine. The many proteins involved in T3SS construction are tightly regulated due to its role in pathogenesis and motility. Here, starting with the 35 kb Salmonella pathogenicity island 1 (SPI-1), we eliminated internal regulation and simplified the genetics by removing or recoding genes, scrambling gene order and replacing all non-coding DNA with synthetic genetic parts. This process results in a 16 kb cluster that shares no sequence identity, regulation or organizational principles with SPI-1...
May 9, 2017: Nature Communications
https://www.readbyqxmd.com/read/28484445/bile-sensing-the-activation-of-vibrio-parahaemolyticus-virulence
#11
Vengadesh Letchumanan, Kok-Gan Chan, Tahir M Khan, Sarah I Bukhari, Nurul-Syakima Ab Mutalib, Bey-Hing Goh, Learn-Han Lee
Bacteria must develop resistance to various inhospitable conditions in order to survive in the human gastrointestinal tract. Bile, which is secreted by the liver, and plays an important role in food digestion also has antimicrobial properties and is able to disrupt cellular homeostasis. Paradoxically, although bile is one of the guts defenses, many studies have reported that bacteria such as Vibrio parahaemolyticus can sense bile and use its presence as an environmental cue to upregulate virulence genes during infection...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28478073/biochemical-and-biophysical-characterization-of-cytokine-like-protein-1-cytl1
#12
Aurelie Tomczak, Kavita Singh, Apostolos G Gittis, Joohee Lee, David N Garboczi, Philip M Murphy
Cytokine-like protein 1 (CYTL1) is a small widely expressed secreted protein lacking significant primary sequence homology to any other known protein. CYTL1 expression appears to be highest in the hematopoietic system and in chondrocytes; however, maintenance of cartilage in mouse models of arthritis is its only reported function in vivo. Despite lacking sequence homology to chemokines, CYTL1 is predicted by computational methods to fold like a chemokine, and has been reported to function as a chemotactic agonist at the chemokine receptor CCR2 in mouse monocyte/macrophages...
May 4, 2017: Cytokine
https://www.readbyqxmd.com/read/28473832/how-escherichia-coli-circumvent-complement-mediated-killing
#13
REVIEW
Afonso G Abreu, Angela S Barbosa
Complement is a crucial arm of the innate immune response against invading bacterial pathogens, and one of its main functions is to recognize and destroy target cells. Similar to other pathogens, Escherichia coli has evolved mechanisms to overcome complement activation. It is well known that capsular polysaccharide may confer resistance to complement-mediated killing and phagocytosis, being one of the strategies adopted by this bacterium to survive in serum. In addition, proteases produced by E. coli have been shown to downregulate the complement system...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28469711/capsular-polysaccharide-inhibits-adhesion-of-bifidobacterium-longum-105-a-to-enterocyte-like-caco-2-cells-and-phagocytosis-by-macrophages
#14
Amin Tahoun, Hisayoshi Masutani, Hanem El-Sharkawy, Trudi Gillespie, Ryo P Honda, Kazuo Kuwata, Mizuho Inagaki, Tomio Yabe, Izumi Nomura, Tohru Suzuki
BACKGROUND: Bifidobacterium longum 105-A produces markedly high amounts of capsular polysaccharides (CPS) and exopolysaccharides (EPS) that should play distinct roles in bacterial-host interactions. To identify the biological function of B. longum 105-A CPS/EPS, we carried out an informatics survey of the genome and identified the EPS-encoding genetic locus of B. longum 105-A that is responsible for the production of CPS/EPS. The role of CPS/EPS in the adaptation to gut tract environment and bacteria-gut cell interactions was investigated using the ΔcpsD mutant...
2017: Gut Pathogens
https://www.readbyqxmd.com/read/28469612/fis-regulates-type-iii-secretion-system-by-influencing-the-transcription-of-exsa-in-pseudomonas-aeruginosa-strain-pa14
#15
Xuan Deng, Mei Li, Xiaolei Pan, Ruiping Zheng, Chang Liu, Fei Chen, Xue Liu, Zhihui Cheng, Shouguang Jin, Weihui Wu
Fis is a versatile DNA binding protein in bacteria. It has been demonstrated in multiple bacteria that Fis plays crucial roles in regulating bacterial virulence factors and optimizing bacterial adaptation to various environments. However, the role of Fis in Pseudomonas aeruginosa virulence as well as gene regulation remains largely unknown. Here, we found that Fis was required for the virulence of P. aeruginosa in a murine acute pneumonia model. Transcriptome analysis revealed that expression of T3SS genes, including master regulator ExsA, was defective in a fis::Tn mutant...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28469603/targeted-modification-of-a-novel-amphibian-antimicrobial-peptide-from-phyllomedusa-tarsius-to-enhance-its-activity-against-mrsa-and-microbial-biofilm
#16
Yitian Gao, Di Wu, Lei Wang, Chen Lin, Chengbang Ma, Xinping Xi, Mei Zhou, Jinao Duan, Olaf R P Bininda-Emonds, Tianbao Chen, Chris Shaw
Antimicrobial peptides (AMPs) in the skin secretions of amphibians are fundamental components of a unique defense system that has evolved to protect these hosts from microbial invasion. Medusins constitute a recently-discovered AMP family from phyllomedusine leaf frog skin and exhibit highly-conserved structural characteristics. Here, we report a novel medusin, medusin-PT, from the skin secretion of the Tarsier Leaf Frog, Phyllomedusa tarsius. The mature peptide was initially identified from its cloned biosynthetic precursor-encoding cDNA as obtained by the rapid amplification of cDNA ends (RACE) method...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28468643/recombinant-salmonella-expressing-ssph2-esci-fusion-protein-limits-its-colonization-in-mice
#17
Maozhi Hu, Weixin Zhao, Wei Gao, Wenhua Li, Chuang Meng, Qiuxiang Yan, Yuyang Wang, Xiaohui Zhou, Shizhong Geng, Zhiming Pan, Guiyou Cui, Xinan Jiao
BACKGROUND: Activation of inflammasome contributes to the clearance of intracellular bacteria. C-terminus of E. coli EscI protein can activate NLRC4 (NLR family, CARD domain containing-4) inflammasome in macrophages. The purpose of this study was to determine if activation of NLRC4 inflammasome by EscI can reduce the colonization of Salmonella in mice. RESULTS: A recombinant S. typhimurium strain expressing fusion protein of the N-terminal SspH2 (a Salmonella type III secretion system 2 effector) and C-terminal EscI was constructed and designated as X4550(pYA3334-SspH2-EscI)...
May 3, 2017: BMC Immunology
https://www.readbyqxmd.com/read/28467926/a-specific-gut-microbiota-dysbiosis-of-type-2-diabetic-mice-induces-glp-1-resistance-through-an-enteric-no-dependent-and-gut-brain-axis-mechanism
#18
Estelle Grasset, Anthony Puel, Julie Charpentier, Xavier Collet, Jeffrey E Christensen, François Tercé, Rémy Burcelin
Glucagon-like peptide-1 (GLP-1)-based therapies control glycemia in type 2 diabetic (T2D) patients. However, in some patients the treatment must be discontinued, defining a state of GLP-1 resistance. In animal models we identified a specific set of ileum bacteria impairing the GLP-1-activated gut-brain axis for the control of insulin secretion and gastric emptying. Using prediction algorithms, we identified bacterial pathways related to amino acid metabolism and transport system modules associated to GLP-1 resistance...
May 2, 2017: Cell Metabolism
https://www.readbyqxmd.com/read/28458670/gut-microbiota-species-can-provoke-both-inflammatory-and-tolerogenic-immune-responses-in-human-dendritic-cells-mediated-by-retinoic-acid-receptor-alpha-ligation
#19
Krisztian Bene, Zsofia Varga, Viktor O Petrov, Nadiya Boyko, Eva Rajnavolgyi
Dendritic cells are considered as the main coordinators of both mucosal and systemic immune responses, thus playing a determining role in shaping the outcome of effector cell responses. However, it is still uncovered how primary human monocyte-derived DC (moDC) populations drive the polarization of helper T (Th) cells in the presence of commensal bacteria harboring unique immunomodulatory properties. Furthermore, the individual members of the gut microbiota have the potential to modulate the outcome of immune responses and shape the immunogenicity of differentiating moDCs via the activation of retinoic acid receptor alpha (RARα)...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28452085/use-of-chimeric-type-iv-secretion-systems-to-define-contributions-of-outer-membrane-subassemblies-for-contact-dependent-translocation
#20
Jay E Gordon, Tiago R D Costa, Roosheel S Patel, Christian Gonzalez-Rivera, Mayukh K Sarkar, Elena V Orlova, Gabriel Waksman, Peter J Christie
Recent studies have shown that conjugation systems of Gram-negative bacteria are composed of distinct inner and outer membrane core complexes (IMCs and OMCCs, respectively). Here, we functionally characterized the OMCC, focusing first on a cap domain that forms a channel across the outer membrane. Strikingly, the OMCC caps of the Escherichia coli pKM101 Tra and Agrobacterium tumefaciens VirB/VirD4 systems are completely dispensable for substrate transfer, but required for formation of conjugative pili. The pKM101 OMCC cap and extended pilus also are dispensable for activation of a Pseudomonas aeruginosa type VI secretion system (T6SS)...
April 27, 2017: Molecular Microbiology
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