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Virulence Regulation

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https://www.readbyqxmd.com/read/28108389/development-of-clostridium-difficile-r20291%C3%AE-paloc-model-strains-and-in-vitro-methodologies-reveals-cdtr-is-required-for-the-production-of-cdt-to-cytotoxic-levels
#1
T W Bilverstone, N L Kinsmore, N P Minton, S A Kuehne
Assessing the regulation of Clostridium difficile transferase (CDT), is complicated by the presence of a Pathogenicity locus (PaLoc) which encodes Toxins A and B. Here we developed R20291ΔPaLoc model strains and cell-based assays to quantify CDT-mediated virulence. Their application demonstrated that the transcriptional regulator, CdtR, was required for CDT-mediated cytotoxicity.
January 17, 2017: Anaerobe
https://www.readbyqxmd.com/read/28107409/targeted-deletion-of-a-plasmodium-site-2-protease-impairs-life-cycle-progression-in-the-mammalian-host
#2
Konstantinos Koussis, Evi Goulielmaki, Anna Chalari, Chrislaine Withers-Martinez, Inga Siden-Kiamos, Kai Matuschewski, Thanasis G Loukeris
Site-2 proteases (S2P) belong to the M50 family of metalloproteases, which typically perform essential roles by mediating activation of membrane-bound transcription factors through regulated intramembrane proteolysis (RIP). Protease-dependent liberation of dormant transcription factors triggers diverse cellular responses, such as sterol regulation, Notch signalling and the unfolded protein response. Plasmodium parasites rely on regulated proteolysis for controlling essential pathways throughout the life cycle...
2017: PloS One
https://www.readbyqxmd.com/read/28106859/burkholderia-cepacia-complex-regulation-of-virulence-gene-expression-a-review
#3
REVIEW
Sílvia A Sousa, Joana R Feliciano, Tiago Pita, Soraia I Guerreiro, Jorge H Leitão
Burkholderia cepacia complex (Bcc) bacteria emerged as opportunistic pathogens in cystic fibrosis and immunocompromised patients. Their eradication is very difficult due to the high level of intrinsic resistance to clinically relevant antibiotics. Bcc bacteria have large and complex genomes, composed of two to four replicons, with variable numbers of insertion sequences. The complexity of Bcc genomes confers a high genomic plasticity to these bacteria, allowing their adaptation and survival to diverse habitats, including the human host...
January 19, 2017: Genes
https://www.readbyqxmd.com/read/28106797/the-complex-relationship-between-virulence-and-antibiotic-resistance
#4
REVIEW
Meredith Schroeder, Benjamin D Brooks, Amanda E Brooks
Antibiotic resistance, prompted by the overuse of antimicrobial agents, may arise from a variety of mechanisms, particularly horizontal gene transfer of virulence and antibiotic resistance genes, which is often facilitated by biofilm formation. The importance of phenotypic changes seen in a biofilm, which lead to genotypic alterations, cannot be overstated. Irrespective of if the biofilm is single microbe or polymicrobial, bacteria, protected within a biofilm from the external environment, communicate through signal transduction pathways (e...
January 18, 2017: Genes
https://www.readbyqxmd.com/read/28106310/mechanism-of-type-iii-protein-secretion-regulation-of-flha-conformation-by-a-functionally-critical-charged-residue-cluster
#5
Marc Erhardt, Paige Wheatley, Eun A Kim, Takanori Hirano, Yang Zhang, Mayukh K Sarkar, Kelly T Hughes, David F Blair
The bacterial flagellum contains a specialized secretion apparatus in its base that pumps certain protein subunits through the growing structure to their sites of installation beyond the membrane. A related apparatus functions in the injectisomes of gram-negative pathogens to export virulence factors into host cells. This mode of protein export is termed type-III secretion (T3S). Details of the T3S mechanism are unclear. It is energized by the proton gradient; here, a mutational approach was used to identify proton-binding groups that might function in transport...
January 20, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28105572/proteome-wide-identification-of-iron-binding-proteins-of-xanthomonas-translucens-pv-undulosa-focus-on-secretory-virulent-proteins
#6
Ankita Sharma, Dixit Sharma, Shailender Kumar Verma
Xanthomonas translucens pv. undulosa (Xtu) causes Bacterial Leaf Streak disease in the staple food crops such as wheat and barley. The survival strategies of pathogen and host are determined by the complex interactions occurring between the host plants and the pathogenic microbes. Iron binding proteins are important in the plant-microbe interactions as they are indulged in enzyme catalysis, virulence, metabolic and transport activities. In the presented study, we have identified that ~9.8% of Xtu proteome possess iron binding sequence motifs...
January 19, 2017: Biometals: An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine
https://www.readbyqxmd.com/read/28104617/staphylococcus-aureus-pathogenesis-in-diverse-host-environments
#7
Divya Balasubramanian, Lamia Harper, Bo Shopsin, Victor J Torres
Staphylococcus aureus (S. aureus) is an eminent human pathogen that can colonize the human host and cause severe, life-threatening illnesses. This bacterium can reside in and infect a wide range of host tissues, ranging from superficial surfaces like the skin to deeper tissues such as in the gastrointestinal tract, heart and bones. Due to its multifaceted lifestyle, S. aureus uses complex regulatory networks to sense diverse signals that enable it to adapt to different environments and modulate virulence. In this mini-review, we explore well-characterized environmental and host cues that S...
January 18, 2017: Pathogens and Disease
https://www.readbyqxmd.com/read/28102119/glutathione-and-glutathione-transferase-omega-1-as-key-posttranslational-regulators-in-macrophages
#8
Mark M Hughes, Anne F McGettrick, Luke A J O'Neill
Macrophage activation during phagocytosis or by pattern recognition receptors, such as Toll-like receptor 4, leads to the accumulation of reactive oxygen species (ROS). ROS act as a microbicidal defense mechanism, promoting clearance of infection, allowing for resolution of inflammation. Overproduction of ROS, however, overwhelms our cellular antioxidant defense system, promoting oxidation of protein machinery, leading to macrophage dysregulation and pathophysiology of chronic inflammatory conditions, such as atherosclerosis...
January 2017: Microbiology Spectrum
https://www.readbyqxmd.com/read/28100304/iron-responsive-like-elements-in-the-parasite-entamoeba-histolytica
#9
Liliana Soto-Castro, Laura Yuliana Plata-Guzman, Elisa Elvira Figueroa-Angulo, Jaeson Calla-Choque, Magda Reyes-Lopez, Mireya DE LA Garza, Nidia Leon-Sicairos, Jose Antonio Garzon-Tiznado, Rossana Arroyo, Claudia Leon-Sicairos
In Entamoeba histolytica, iron modulates virulence and gene expression via unknown regulatory mechanisms. The existence of a posttranscriptional iron regulatory system parallel to the IRE/IRP (Iron-Responsive Element/Iron Regulatory Protein) system in the protozoan Trichomonas vaginalis has recently been reported. Due to their evolutionary closeness and the importance of iron for growth and virulence in these protozoa, we hypothesized the existence of an IRE/IRP-like mechanism in E. histolytica. To determine the presence of IRE-like elements in some mRNAs from this parasite, we performed in silico analyses of the 5'- and 3'-UTRs of mRNAs encoding virulence factors and cytoskeleton, ribosomal, and metabolism proteins...
January 18, 2017: Microbiology
https://www.readbyqxmd.com/read/28099780/the-genetic-architecture-of-defense-as-resistance-to-and-tolerance-of-bacterial-infection-in-drosophila-melanogaster
#10
Virginia M Howick, Brian P Lazzaro
Defense against pathogenic infection can take two forms: resistance and tolerance. Resistance is the ability of the host to limit a pathogen burden, whereas tolerance is the ability to limit the negative consequences of infection at a given level of infection intensity. Evolutionarily, a tolerance strategy that is independent of resistance could allow the host to avoid mounting a costly immune response and, theoretically, to avoid a coevolutionary arms race between pathogen virulence and host resistance. Biomedically, understanding the mechanisms of tolerance and how they relate to resistance could potentially yield treatment strategies that focus on health improvement instead of pathogen elimination...
January 18, 2017: Molecular Ecology
https://www.readbyqxmd.com/read/28097724/unphosphorylated-eiia-ntr-induces-clpap-mediated-degradation-of-rpos-in-azotobacter-vinelandii
#11
Luis Felipe Muriel-Millán, Soledad Moreno, Ramsés Gallegos-Monterrosa, Guadalupe Espín
The nitrogen-related phosphotransferase system (PTS(Ntr) ) is composed of the EI(Ntr) , NPr and EIIA(Ntr) proteins that form a phosphorylation cascade from phosphoenolpyruvate. PTS(Ntr) is a global regulatory system present in most Gram-negative bacteria that controls some pivotal processes such as potassium and phosphate homeostasis, virulence, nitrogen fixation and ABC transport activation. In the soil bacterium Azotobacter vinelandii, unphosphorylated EIIA(Ntr) negatively regulates the expression of genes related to the synthesis of the bioplastic polyester poly-β-hydroxybutyrate (PHB) and cyst-specific lipids alkylresorcinols (ARs)...
January 18, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28097715/c-di-amp-modulates-listeria-monocytogenes-central-metabolism-to-regulate-growth-antibiotic-resistance-and-osmoregulation
#12
Aaron T Whiteley, Nicholas E Garelis, Bret N Peterson, Philip H Choi, Liang Tong, Joshua J Woodward, Daniel A Portnoy
Cyclic di-adenosine monophosphate (c-di-AMP) is a conserved nucleotide second messenger critical for bacterial growth and resistance to cell wall-active antibiotics. In Listeria monocytogenes, the sole diadenylate cyclase, DacA, is essential in rich, but not synthetic media and ΔdacA mutants are highly sensitive to the β-lactam antibiotic cefuroxime. In this study, loss of function mutations in the oligopeptide importer (oppABCDF) and glycine betaine importer (gbuABC) allowed ΔdacA mutants to grow in rich medium...
January 18, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28096329/tissue-dual-rna-seq-allows-fast-discovery-of-infection-specific-functions-and-riboregulators-shaping-host-pathogen-transcriptomes
#13
Aaron M Nuss, Michael Beckstette, Maria Pimenova, Carina Schmühl, Wiebke Opitz, Fabio Pisano, Ann Kathrin Heroven, Petra Dersch
Pathogenic bacteria need to rapidly adjust their virulence and fitness program to prevent eradication by the host. So far, underlying adaptation processes that drive pathogenesis have mostly been studied in vitro, neglecting the true complexity of host-induced stimuli acting on the invading pathogen. In this study, we developed an unbiased experimental approach that allows simultaneous monitoring of genome-wide infection-linked transcriptional alterations of the host and colonizing extracellular pathogens. Using this tool for Yersinia pseudotuberculosis-infected lymphatic tissues, we revealed numerous alterations of host transcripts associated with inflammatory and acute-phase responses, coagulative activities, and transition metal ion sequestration, highlighting that the immune response is dominated by infiltrating neutrophils and elicits a mixed TH17/TH1 response...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28095465/leishmania-hasp-and-sherp-genes-are-required-for-in-vivo-differentiation-parasite-transmission-and-virulence-attenuation-in-the-host
#14
Johannes S P Doehl, Jovana Sádlová, Hamide Aslan, Kateřina Pružinová, Sonia Metangmo, Jan Votýpka, Shaden Kamhawi, Petr Volf, Deborah F Smith
Differentiation of extracellular Leishmania promastigotes within their sand fly vector, termed metacyclogenesis, is considered to be essential for parasites to regain mammalian host infectivity. Metacyclogenesis is accompanied by changes in the local parasite environment, including secretion of complex glycoconjugates within the promastigote secretory gel and colonization and degradation of the sand fly stomodeal valve. Deletion of the stage-regulated HASP and SHERP genes on chromosome 23 of Leishmania major is known to stall metacyclogenesis in the sand fly but not in in vitro culture...
January 17, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28094526/1h-nmr-based-global-metabolic-studies-of-pseudomonas-aeruginosa-upon-exposure-of-the-quorum-sensing-inhibitor-resveratrol
#15
Tongtong Chen, Jiyang Sheng, Yonghong Fu, Ming-Hui Li, Jun-Song Wang, Aiqun Jia
Quorum sensing (QS) is a process of bacterial communication that has been a novel target for drug discovery. Pyocyanin quantification assay confirmed that resveratrol was an effective quorum sensing inhibitor (QSI) against Pseudomonas aeruginosa PAO1. In this study, the global metabolite changes of P. aeruginosa PAO1 exposed to QSI resveratrol were investigated by 1H-NMR spectroscopy. A total of 40 metabolites containing amino acids, organic acid, organic amine and energy storage compounds were identified. The changed metabolic profile indicated that resveratrol influenced pathways including oxidative stress, protein synthesis and energy metabolism...
January 17, 2017: Journal of Proteome Research
https://www.readbyqxmd.com/read/28093838/fusaric-acid-contributes-to-virulence-of-fusarium-oxysporum-on-plant-and-mammalian-hosts
#16
Cristina López-Díaz, Vahid Rahjoo, Michael Sulyok, Veronica Ghionna, Adela Martín-Vicente, Javier Capilla, Antonio Di Pietro, Manuel S López-Berges
Fusaric acid (FA) is among the oldest identified secondary metabolites produced by Fusarium species, known for a long time to display strong phytotoxicity and moderate toxicity to animal cells; however, the cellular targets of FA as well as its function in fungal pathogenicity remain unknown. Here, we investigated the role of FA in Fusarium oxysporum, a soil-borne cross-kingdom pathogen that causes vascular wilt on more than a hundred plant species and opportunistic infections in humans. Targeted deletion of fub1, encoding a predicted orthologue of the polyketide synthase involved in FA biosynthesis in F...
January 17, 2017: Molecular Plant Pathology
https://www.readbyqxmd.com/read/28093309/paracoccidioides-spp-catalases-and-their-role-in-antioxidant-defense-against-host-defense-responses
#17
Diana Tamayo, José F Muñoz, Agostinho J Almeida, Juan D Puerta, Ángela Restrepo, Christina A Cuomo, Juan G McEwen, Orville Hernández
Dimorphic human pathogenic fungi interact with host effector cells resisting their microbicidal mechanisms. Yeast cells are able of surviving within the tough environment of the phagolysosome by expressing an antioxidant defense system that provides protection against host-derived reactive oxygen species (ROS). This includes the production of catalases (CATs). Here we identified and analyzed the role of CAT isoforms in Paracoccidioides, the etiological agent of paracoccidioidomycosis. Firstly, we found that one of these isoforms was absent in the closely related dimorphic pathogen Coccidioides and dermatophytes, but all of them were conserved in Paracoccidioides, Histoplasma and Blastomyces species...
January 13, 2017: Fungal Genetics and Biology: FG & B
https://www.readbyqxmd.com/read/28091933/flagellar-regulation-and-virulence-in-the-entomopathogenic-bacteria-xenorhabdus-nematophila-and-photorhabdus-luminescens
#18
Alain Givaudan, Anne Lanois
There is a complex interplay between the regulation of flagellar motility and the expression of virulence factors in many bacterial pathogens. Here, we review the literature on the direct and indirect roles of flagellar motility in mediating the tripartite interaction between entomopathogenic bacteria (Photorhabdus and Xenorhabdus), their nematode hosts, and their insect targets. First, we describe the swimming and swarming motility of insect pathogenic bacteria and its impact on insect colonization. Then, we describe the coupling between the expression of flagellar and virulence genes and the dynamic of expression of the flagellar regulon during invertebrate infection...
December 28, 2016: Current Topics in Microbiology and Immunology
https://www.readbyqxmd.com/read/28091587/bacillus-volatiles-adversely-affect-the-physiology-and-ultra-structure-of-ralstonia-solanacearum-and-induce-systemic-resistance-in-tobacco-against-bacterial-wilt
#19
Hafiz Abdul Samad Tahir, Qin Gu, Huijun Wu, Yuedi Niu, Rong Huo, Xuewen Gao
Volatile organic compounds (VOCs) produced by various bacteria have significant potential to enhance plant growth and to control phytopathogens. Six of the most effective antagonistic Bacillus spp. were used in this study against Ralstonia solanacearum (Rsc) TBBS1, the causal agent of bacterial wilt disease in tobacco. Bacillus amyloliquefaciens FZB42 and Bacillus artrophaeus LSSC22 had the strongest inhibitory effect against Rsc. Thirteen VOCs produced by FZB42 and 10 by LSSC22 were identified using gas chromatography-mass spectrometry analysis...
January 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28090277/anti-quorum-sensing-activity-of-substances-isolated-from-wild-berry-associated-bacteria
#20
Suha M Abudoleh, Adel M Mahasneh
BACKGROUND: Quorum Sensing (QS) is a mechanism used by bacteria to determine their physiological activities and coordinate gene expression based on cell to cell signaling. Many bacterial physiological functions are under the regulation of quorum sensing such as virulence, luminescence, motility, sporulation and biofilm formation. The aim of the present study was to isolate and characterize Quorum Sensing Inhibitory (QSI) substances from epiphytic bacteria residing on wild berries surfaces...
January 2017: Avicenna Journal of Medical Biotechnology
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