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Virulence Regulation

Jamie L Burgess, R Alan Burgess, Yalemi Morales, Jenna M Bouvang, Sean J Johnson, Nicholas E Dickenson
Like many Gram-negative pathogens, Shigella rely on a complex type three secretion system (T3SS) to inject effector proteins into host cells, take over host functions, and ultimately establish infection. Despite these critical roles, the energetics and regulatory mechanisms controlling the T3SS and pathogen virulence remain largely unclear. In this study, we present a series of high-resolution crystal structures of Spa47 and use the structures to model an activated Spa47 oligomer, finding that ATP hydrolysis may be supported by specific sidechain contributions from adjacent protomers within the complex...
October 21, 2016: Journal of Biological Chemistry
Narges Abdali, Jerry Matthew Parks, Keith Haynes, Julie L Chaney, Adam T Green, David Wolloscheck, John K Walker, Valentin V Rybenkov, Jerome Yves Baudry, Jeremy C Smith, Helen I Zgurskaya
Antibiotic resistance is a major threat to human welfare. Inhibitors of multidrug efflux pumps (EPIs) are promising alternative therapeutics that could revive activities of antibiotics and reduce bacterial virulence. Identification of new druggable sites for inhibition is critical for development of effective EPIs, especially in light of constantly emerging resistance. Here, we describe EPIs that interact with periplasmic membrane fusion proteins, critical components of efflux pumps that are responsible for the activation of the transporter and the recruitment of the outer-membrane channel...
October 21, 2016: ACS Infectious Diseases
Yuying Sang, Yaru Wang, Hong Ni, Anne-Claire Cazalé, Yi-Min She, Nemo Peeters, Alberto P Macho
The subversion of plant cellular functions is essential for bacterial pathogens to proliferate in host plants and cause disease. Most bacterial plant pathogens employ a type-III secretion system to inject type-III effector (T3E) proteins inside plant cells, where they contribute to the pathogen-induced alteration of plant physiology. In this work, we found that the Ralstonia solanacearum T3E RipAY suppresses plant immune responses triggered by bacterial elicitors and by the phytohormone salicylic acid. Further biochemical analysis indicated that RipAY associates in planta with thioredoxins from Nicotiana benthamiana and Arabidopsis...
October 21, 2016: Molecular Plant Pathology
Sarah Thabet, Nada Souissi
The mycobacterial insertion sequence IS6110 proved crucial in deciphering tuberculosis (TB) transmission dynamics. This sequence was also shown to play an important role in the pathogenicity (transmission ability and/or virulence) of Mycobacterium tuberculosis, the main causative agent of TB in humans. In this study, we explored the usefulness of IS6110 and its potential as a phylogenetic/typing marker. We also analyzed the genetic polymorphism and evolutionary trends (selective pressure) of its transposase-encoding open reading frames (ORFs), A and B, using the maximum likelihood method...
October 20, 2016: Molecular Biology Reports
Ranjith Rajendran, Ali May, Leighann Sherry, Ryan Kean, Craig Williams, Brian L Jones, Karl V Burgess, Jaap Heringa, Sanne Abeln, Bernd W Brandt, Carol A Munro, Gordon Ramage
Candida albicans biofilm formation is an important virulence factor in the pathogenesis of disease, a characteristic which has been shown to be heterogeneous in clinical isolates. Using an unbiased computational approach we investigated the central metabolic pathways driving biofilm heterogeneity. Transcripts from high (HBF) and low (LBF) biofilm forming isolates were analysed by RNA sequencing, with 6312 genes identified to be expressed in these two phenotypes. With a dedicated computational approach we identified and validated a significantly differentially expressed subnetwork of genes associated with these biofilm phenotypes...
October 21, 2016: Scientific Reports
Vincent Le Coz, Chaobin Zhu, Aurore Devocelle, Aimé Vazquez, Claude Boucheix, Sandy Azzi, Cindy Gallerne, Pierre Eid, Séverine Lecourt, Julien Giron-Michel
Melanoma is a particularly virulent human cancer, due to its resistance to conventional treatments and high frequency of metastasis. Melanomas contain a fraction of cells, the melanoma-initiating cells (MICs), responsible for tumor propagation and relapse. Identification of the molecular pathways supporting MICs is, therefore, vital for the development of targeted treatments. One factor produced by melanoma cells and their microenvironment, insulin-like growth factor-1 (IGF- 1), is linked to epithelial-mesenchymal transition (EMT) and stemness features in several cancers...
October 18, 2016: Oncotarget
Gina Leisching, Ray-Dean Pietersen, Carel van Heerden, Paul van Helden, Ian Wiid, Bienyameen Baker
The distinguishing factors that characterize the host response to infection with virulent Mycobacterium tuberculosis (M.tb) are largely confounding. We present an infection study with two genetically closely related M.tb strains that have vastly different pathogenic characteristics. The early host response to infection with these detergent-free cultured strains was analysed through RNAseq in an attempt to provide information on the subtleties which may ultimately contribute to the virulent phenotype. Murine bone marrow derived macrophages (BMDMs) were infected with either a hyper- (R5527) or hypovirulent (R1507) Beijing M...
October 20, 2016: Virulence
Kyle A Tipton, Marjan Farokhyfar, Philip N Rather
Colony opacity phase variation in Acinetobacter baumannii strain AB5075 is regulated by a reversible high-frequency switch. Transposon mutagenesis was used to generate mutations that decreased the opaque to translucent switch and a gene encoding a predicted periplasmic membrane fusion component of a resistance-nodulation-cell division (RND)-type efflux system was isolated. This gene was designated arpA and immediately downstream was a gene designated arpB that encodes a predicted membrane transporter of RND-type systems...
October 19, 2016: MicrobiologyOpen
Dharmaprakash Viszwapriya, Ganapathy Ashwinkumar Subramenium, Solai Radhika, Shunmugiah Karutha Pandian
Streptococcus mutans, a multivirulent pathogen is considered the primary etiological agent in dental caries. Development of antibiotic resistance in the pathogen has created a need for novel antagonistic agents which can control the virulence of the organism and reduce resistance development. The present study demonstrates the in vitro anti-virulence potential of betulin (lup-20(29)-ene-3β,28-diol), an abundantly available plant triterpenoid against S. mutans UA159. Betulin exhibited significant dose dependent antibiofilm activity without affecting bacterial viability...
October 18, 2016: Antonie Van Leeuwenhoek
Melissa Agnello, Steven E Finkel, Annie Wong-Beringer
Fluoroquinolone (FQ) resistance is highly prevalent among clinical strains of Pseudomonas aeruginosa, limiting treatment options. We have reported previously that highly virulent strains containing the exoU gene of the type III secretion system are more likely to be FQ-resistant than strains containing the exoS gene, as well as more likely to acquire resistance-conferring mutations in gyrA/B and parC/E. We hypothesize that FQ-resistance imposes a lower fitness cost on exoU compared to exoS strains, thus allowing for better adaptation to the FQ-rich clinical environment...
2016: Frontiers in Microbiology
Qianqian Xu, Yuqiu Chen, Wenjun Zhao, Tingting Zhang, Chenggang Liu, Tianming Qi, Zongxi Han, Yuhao Shao, Deying Ma, Shengwang Liu
Newcastle disease (ND), caused by virulent strains of Newcastle disease virus (NDV), is a highly contagious disease of birds that is responsible for heavy economic losses for the poultry industry worldwide. However, little is known about host-virus interactions in waterfowl, goose. In this study, we aim to characterize the host immune response in goose, based on the previous reports on the host response to NDV in chickens. Here, we evaluated viral replication and mRNA expression of 27 immune-related genes in 10 tissues of geese challenged with a genotype VIId NDV strain of goose origin (go/CH/LHLJ/1/06)...
2016: Frontiers in Microbiology
Juan Huang, Meiling Yang, Lu Lu, Xiaoming Zhang
RNA silencing is a conserved mechanism that utilizes small RNAs (sRNAs) to direct the regulation of gene expression at the transcriptional or post-transcriptional level. Plants utilizing RNA silencing machinery to defend pathogen infection was first identified in plant-virus interaction and later was observed in distinct plant-pathogen interactions. RNA silencing is not only responsible for suppressing RNA accumulation and movement of virus and viroid, but also facilitates plant immune responses against bacterial, oomycete, and fungal infection...
2016: Frontiers in Microbiology
Shuai Huang, Aruna Balgi, Yaping Pan, Meng Li, Xiaoran Zhang, Lilin Du, Ming Zhou, Michel Roberge, Xin Li
Nucleotide-binding leucine-rich repeat (NLR) proteins serve as immune receptors in both plants and animals. To identify components required for NLR-mediated immunity, we designed and carried out a chemical genetics screen to search for small molecules that can alter resistance responses in Arabidopsis thaliana. From 13,600 compounds, we identified Ro 8-4304 that is able to specifically suppress the severe autoimmune phenotypes of chs3-2D (chilling sensitive 3, 2D), including the arrested growth morphology and heightened PR (Pathogenesis Related) gene expression...
October 15, 2016: Molecular Plant
Yaovi M G Hounmanou, Robinson H Mdegela, Tamègnon V Dougnon, Ofred J Mhongole, Edward S Mayila, Joseph Malakalinga, George Makingi, Anders Dalsgaard
BACKGROUND: Cholera, one of the world's deadliest infectious diseases, remains rampant and frequent in Tanzania and thus hinders existing control measures. The present study was undertaken to evaluate the occurrence of toxigenic Vibrio cholerae O1 in wastewater, fish and vegetables during a non-outbreak period in Morogoro, Tanzania. METHODS: From October 2014 to February 2015, 60 wastewater samples, 60 fish samples from sewage stabilization ponds and 60 wastewater irrigated vegetable samples were collected...
October 18, 2016: BMC Research Notes
Irfan Ahmad, Syed Fazle Rouf, Lei Sun, Annika Cimdins, Sulman Shafeeq, Soazig Le Guyon, Marco Schottkowski, Mikael Rhen, Ute Römling
BACKGROUND: Cellulose, a 1,4 beta-glucan polysaccharide, is produced by a variety of organisms including bacteria. Although the production of cellulose has a high biological, ecological and economical impact, regulatory mechanisms of cellulose biosynthesis are mostly unknown. Family eight cellulases are regularly associated with cellulose biosynthesis operons in bacteria; however, their function is poorly characterized. In this study, we analysed the role of the cellulase BcsZ encoded by the bcsABZC cellulose biosynthesis operon of Salmonella enterica serovar Typhimurium (S...
October 19, 2016: Microbial Cell Factories
Sebastian Hutchinson, Lucy Glover, David Horn
BACKGROUND: African trypanosomes cause lethal diseases in humans and animals and escape host immune attack by switching the expression of Variant Surface Glycoprotein (VSG) genes. The expressed VSGs are located at the ends of telomeric, polycistronic transcription units known as VSG expression sites (VSG-ESs). Each cell has many VSG-ESs but only one is transcribed in bloodstream-form parasites and all of them are inactive upon transmission to the insect vector mid-gut; a subset of monocistronic metacyclic VSG-ESs are then activated in the insect salivary gland...
October 18, 2016: BMC Genomics
S S Garcia, Q Du, H Wu
The oral cavity is a dynamic environment characterized by hundreds of bacterial species, saliva, and an influx of nutrients and metal ions such as copper. Although there is a physiologic level of copper in the saliva, the oral cavity is often challenged with an influx of copper ions. At high concentrations copper is toxic and must therefore be strictly regulated by pathogens for them to persist and cause disease. The cariogenic pathogen Streptococcus mutans manages excess copper using the copYAZ operon that encodes a negative DNA-binding repressor (CopY), the P1-ATPase copper exporter (CopA), and the copper chaperone (CopZ)...
December 21, 2015: Molecular Oral Microbiology
Mariaconcetta Varano, Marco Gaspari, Angela Quirino, Giovanni Cuda, Maria Carla Liberto, Alfredo Focà
Ochrobactrum anthropi is a gram-negative rod belonging to the Brucellaceae family, able to colonize a variety of environments, and actually reported as a human opportunistic pathogen. Despite its low virulence, the bacterium causes a growing number of hospital-acquired infections mainly, but not exclusively, in immunocompromised patients. The aim of this study was to obtain an overview of the global proteome changes occurring in O. anthropi in response to different growth temperatures, in order to achieve a major understanding of the mechanisms by which the bacterium adapts to different habitats and to identify some potential virulence factors...
October 18, 2016: Proteomics
Luisa F Castiblanco, George W Sundin
Bacterial biofilms are multicellular aggregates encased in an extracellular matrix mainly composed of exopolysaccharides (EPSs), protein, and nucleic acids, which determines the architecture of the biofilm. Erwinia amylovora Ea1189 forms a biofilm inside the xylem of its host, that results in vessel plugging and water transport impairment. Production of the EPSs amylovoran and levan are critical for the formation of a mature biofilm. Additionally, cyclic dimeric GMP (c-di-GMP) was reported to positively regulate amylovoran biosynthesis and biofilm formation in E...
October 18, 2016: Molecular Plant Pathology
MyungHee Ku, Yong-Un Baek, Min-Kyu Kwak, Sa-Ouk Kang
BACKGROUND: Glutathione reductase maintains the glutathione level in a reduced state. As previously demonstrated, glutathione is required for cell growth/division and its biosynthesizing-enzyme deficiency causes methylglyoxal accumulation. However, experimental evidences for reciprocal relationships between Cph1-/Efg1-mediated signaling pathway regulation and methylglyoxal production exerted by glutathione reductase on yeast morphology remain unclear. METHODS: Glutathione reductase (GLR1) disruption/overexpression were performed to investigate aspects of pathological/morphological alterations in Candida albicans...
October 14, 2016: Biochimica et Biophysica Acta
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