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Virulence Regulation

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https://www.readbyqxmd.com/read/28346491/a-genetic-switch-controls-the-production-of-flagella-and-toxins-in-clostridium-difficile
#1
Brandon R Anjuwon-Foster, Rita Tamayo
In the human intestinal pathogen Clostridium difficile, flagella promote adherence to intestinal epithelial cells. Flagellar gene expression also indirectly impacts production of the glucosylating toxins, which are essential to diarrheal disease development. Thus, factors that regulate the expression of the flgB operon will likely impact toxin production in addition to flagellar motility. Here, we report the identification a "flagellar switch" that controls the phase variable production of flagella and glucosylating toxins...
March 27, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28346365/an-amylase-like-protein-amyd-is-the-major-negative-regulator-for-%C3%AE-glucan-synthesis-in-aspergillus-nidulans-during-the-asexual-life-cycle
#2
Xiaoxiao He, Shengnan Li, Susan Kaminskyj
α-Glucan affects fungal cell-cell interactions and is important for the virulence of pathogenic fungi. Interfering with production of α-glucan could help to prevent fungal infection. In our previous study, we reported that an amylase-like protein, AmyD, could repress α-glucan accumulation in Aspergillus nidulans. However, the underlying molecular mechanism was not clear. Here, we examined the localization of AmyD and found it was a membrane-associated protein. We studied AmyD function in α-glucan degradation, as well as with other predicted amylase-like proteins and three annotated α-glucanases...
March 27, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28345225/highly-potent-host-external-immunity-acts-as-a-strong-selective-force-enhancing-rapid-parasite-virulence-evolution
#3
Charlotte Rafaluk, Wentao Yang, Andreas Mitschke, Philip Rosenstiel, Hinrich Schulenburg, Gerrit Joop
Virulence is often under selection during host-parasite coevolution. In order to increase fitness, parasites are predicted to circumvent and overcome host immunity. A particular challenge for pathogens are external immune systems, chemical defence systems comprised of potent antimicrobial compounds released by prospective hosts into the environment. We carried out an evolution experiment, allowing for coevolution to occur, with the entomopathogenic fungus, Beauveria bassiana, and the red flour beetle, Tribolium castaneum, which has a well-documented external immune system with strong inhibitory effects against B...
March 26, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28344121/brevibacillus-laterosporus-pathogenesis-and-local-immune-response-regulation-in-the-house-fly-midgut
#4
Maria Elena Mura, Luca Ruiu
The insect midgut represents the primary site of action of the entompathogenic bacterium Brevibacillus laterosporus. Whilst most studies on this microorganism focus on the identification and characterization of possible virulence factors and toxins, little is known about the insect immune defense mechanisms that are activated against this pathogen. In this study we have investigated the local immune response of different house fly stages to B. laterosporus at the transcriptional level, and we tested the hypothesis that an improvement in entomopathogenicity can be achieved by impairing host innate immunity...
March 23, 2017: Journal of Invertebrate Pathology
https://www.readbyqxmd.com/read/28344104/antimicrobial-medium-and-long-chain-free-fatty-acids-prevent-prfa-dependent-activation-of-virulence-genes-in-listeria-monocytogenes
#5
Eva Maria Sternkopf Lillebæk, Stine Lambert Nielsen, Rikke Scheel Thomasen, Nils J Færgeman, Birgitte H Kallipolitis
The foodborne pathogen Listeria monocytogenes is the causative agent of the invasive disease listeriosis. Infection by L. monocytogenes involves bacterial crossing of the intestinal barrier and intracellular replication in a variety of host cells. The PrfA protein is the master regulator of virulence factors required for bacterial entry, intracellular replication and cell-to-cell spread. PrfA-dependent activation of virulence genes occurs primarily in the blood and during intracellular infection. In contrast, PrfA does not play a significant role in regulation of virulence gene expression in the intestinal environment...
March 23, 2017: Research in Microbiology
https://www.readbyqxmd.com/read/28342077/the-influences-of-bacillus-subtilis-on-the-virulence-of-aeromonas-hydrophila-and-expression-of-luxs-gene-of-both-bacteria-under-co-cultivation
#6
Yuwei Ren, Sisi Li, Zhixin Wu, Chengchong Zhou, Ding Zhang, Xiaoxuan Chen
The aim of this study was to explore the influence of Bacillus subtilis CH9 on Aeromonas hydrophila SC2005. The transcription level of virulence genes of A. hydrophila SC2005 and its hemolysin activity as well as its cytotoxicity were analyzed when B. subtilis CH9 and A. hydrophila SC2005 were co-cultured. The results indicated that the transcription levels of four virulence genes of A. hydrophila, including aer, ahyB, hcp, and emp, decreased when A. hydrophila was cultured with B. subtilis CH9. Furthermore, the extracellular products of A...
March 24, 2017: Current Microbiology
https://www.readbyqxmd.com/read/28340510/the-diverse-family-of-mmpl-transporters-in-mycobacteria-from-regulation-to-antimicrobial-developments
#7
REVIEW
Albertus Viljoen, Violaine Dubois, Fabienne Girard-Misguich, Mickael Blaise, Jean-Louis Herrmann, Laurent Kremer
Mycobacterial genomes contain large sets of loci encoding membrane proteins that belong to a family of multidrug resistance pumps designated Resistance-Nodulation-Cell Division (RND) permeases. Mycobacterial membrane protein Large (MmpL) transporters represent a subclass of RND transporters known to participate in the export of lipid components across the cell envelope. These surface-exposed lipids with unusual structures play key roles in the physiology of mycobacteria and/or can act as virulence factors and immunomodulators...
March 24, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28340252/urinary-tract-infection-recent-insight-into-the-evolutionary-arms-race-between-uropathogenic-escherichia-coli-and-our-immune-system
#8
Sebastian Schwab, Katarzyna Jobin, Christian Kurts
Urinary tract infections (UTIs) are among the most common bacterial infections worldwide. Humans evolved various immune-dependent and independent defense mechanisms, while pathogens evolved multiple virulence factors to fight back. This article summarizes recent findings regarding the arms race between hosts and pathogens in UTIs. It was recently reported that macrophage subsets regulate neutrophil-mediated defense in primary UTIs but seem to subvert adaptive immunity upon re-infection. Moreover, some bacterial strains can survive inside macrophages, leading to recurrent infections...
March 15, 2017: Nephrology, Dialysis, Transplantation
https://www.readbyqxmd.com/read/28337802/the-snf1-activating-kinase-sak1-is-a-key-regulator-of-metabolic-adaptation-and-in-vivo-fitness-of-candida-albicans
#9
Bernardo Ramírez-Zavala, Austin Mottola, Julia Haubenreißer, Sabrina Schneider, Stefanie Allert, Sascha Brunke, Knut Ohlsen, Bernhard Hube, Joachim Morschhäuser
The metabolic flexibility of the opportunistic fungal pathogen Candida albicans is important for colonisation and infection of different host niches. Complex regulatory networks, in which protein kinases play central roles, link metabolism and other virulence-associated traits, such as filamentous growth and stress resistance, and thereby control commensalism and pathogenicity. By screening a protein kinase deletion mutant library that was generated in the present work using an improved SAT1 flipper cassette, we found that the previously uncharacterised kinase Sak1 is a key upstream activator of the protein kinase Snf1, a highly conserved regulator of nutrient stress responses that is essential for viability in C...
March 23, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28337427/comparative-proteomics-analysis-of-human-macrophages-infected-with-virulent-mycobacterium-bovis
#10
Pei Li, Rui Wang, Wenqi Dong, Linlin Hu, Bingbing Zong, Yanyan Zhang, Xiangru Wang, Aizhen Guo, Anding Zhang, Yaozu Xiang, Huanchun Chen, Chen Tan
Mycobacterium bovis (M. bovis), the most common pathogens of tuberculosis (TB), is virulent to human and cattle, and transmission between cattle and humans warrants reconsideration concerning food safety and public health. Recently, efforts have begun to analyze cellular proteomic responses induced by Mycobacterium tuberculosis (M. tb). However, the underlying mechanisms by which virulent M. bovis affects human hosts are not fully understood. For the present study, we utilized a global and comparative labeling strategy of isobaric tag for relative and absolute quantitation (iTRAQ) to assess proteomic changes in the human monocyte cell line (THP-1) using a vaccine strain and two virulent strains H37Rv and M...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28335576/genome-wide-identification-and-evolutionary-analysis-of-sarcocystis-neurona-protein-kinases
#11
Edwin K Murungi, Henry M Kariithi
The apicomplexan parasite Sarcocystis neurona causes equine protozoal myeloencephalitis (EPM), a degenerative neurological disease of horses. Due to its host range expansion, S. neurona is an emerging threat that requires close monitoring. In apicomplexans, protein kinases (PKs) have been implicated in a myriad of critical functions, such as host cell invasion, cell cycle progression and host immune response evasion. Here, we used various bioinformatics methods to define the kinome of S. neurona and phylogenetic relatedness of its PKs to other apicomplexans...
March 21, 2017: Pathogens
https://www.readbyqxmd.com/read/28335027/a-transposon-derived-small-rna-regulates-gene-expression-in-salmonella-typhimurium
#12
Michael J Ellis, Ryan S Trussler, Onella Charles, David B Haniford
Bacterial sRNAs play an important role in regulating many cellular processes including metabolism, outer membrane homeostasis and virulence. Although sRNAs were initially found in intergenic regions, there is emerging evidence that protein coding regions of the genome are a rich reservoir of sRNAs. Here we report that the 5΄UTR of IS200 transposase mRNA (tnpA) is processed to produce regulatory RNAs that affect expression of over 70 genes in Salmonella Typhimurium. We provide evidence that the tnpA derived sRNA base-pairs with invF mRNA to repress expression...
February 21, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334833/chip-seq-analysis-of-the-luxr-type-regulator-vjbr-reveals-novel-insights-into-the-brucella-virulence-gene-expression-network
#13
Claudia L Kleinman, Gabriela Sycz, Hernán R Bonomi, Romina M Rodríguez, Angeles Zorreguieta, Rodrigo Sieira
LuxR-type transcription factors control diverse physiological functions necessary for bacterial adaptation to environmental changes. In the intracellular pathogen Brucella, the LuxR homolog VjbR has been shown to regulate the expression of virulence factors acting at early stages of the intracellular infection and, directly or indirectly, hundreds of additional genes. However, the precise determination of VjbR direct targets has so far proved elusive. Here, we performed chromatin immunoprecipitation of VjbR followed by next-generation sequencing (ChIP-seq)...
March 11, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334389/profiling-diuraphis-noxia-hemiptera-aphididae-transcript-expression-of-the-biotypes-sa1-and-sam-feeding-on-various-triticum-aestivum-varieties
#14
N F V Burger, E Venter, A-M Botha
The intimate relationship between an aphid and its host is mediated by the composition of the secreted saliva. In the present study, aphid heads were sampled and transcript profiling conducted after aphids were fed on their preference host and transferred to a variety of preference and nonpreference hosts. It was found that the virulent Diuraphis noxia (Kurdjumov) (Hemiptera: Aphididae) biotype SAM was able to selectively up-regulate more transcripts when confronted with feeding on a variety of hosts, than was the case with the less virulent D...
March 3, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28334288/genome-sequencing-and-comparative-analysis-of-three-hypermucoviscous-klebsiella-pneumoniae-strains-isolated-in-russia
#15
Angelina A Kislichkina, Anastasia I Lev, Ekaterina V Komisarova, Nadezhda K Fursova, Vera P Myakinina, Tatiana N Mukhina, Alexander A Bogun, Nikolay V Volozhantsev
The prevalence and characteristics of hypermucoviscous (HV) strains among Klebsiella pneumoniae isolated in Russian hospitals were investigated. The HV strains were accounted for 11% K. pneumoniae isolates collected on the period from 2011 to 2016, and were characterized by belonging to K1, K2, K20 and K57 serotypes. Whole genome sequences (WGSs) of K. pneumoniae HV clinical strains KPi261 (SCPM-O-B-7850) and KPB4010 (SCPM-O-B-7846) belonging to K1 and K2 capsular types, as well as WGSs of K. pneumoniae strain KPM9 (SCPM-O-B-7749) of K20 capsular type isolated from freshwater were completed...
March 9, 2017: Pathogens and Disease
https://www.readbyqxmd.com/read/28332578/a-new-class-of-inhibitors-of-the-arac-family-virulence-regulator-vibrio-cholerae-toxt
#16
Anne K Woodbrey, Evans O Onyango, Maria Pellegrini, Gabriela Kovacikova, Ronald K Taylor, Gordon W Gribble, F Jon Kull
Vibrio cholerae is responsible for the diarrheal disease cholera that infects millions of people worldwide. While vaccines protecting against cholera exist, and oral rehydration therapy is an effective treatment method, the disease will remain a global health threat until long-term solutions such as improved sanitation and access to clean water become widely available. Because of this, there is a pressing need for potent therapeutics that can either mitigate cholera symptoms, or act prophylactically to prevent the virulent effects of a cholera infection...
March 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28329249/acetylation-regulates-protein-stability-and-dna-binding-ability-of-hild-to-modulate-salmonella-typhimurium-virulence
#17
Yu Sang, Jie Ren, Ran Qin, Shuting Liu, Zhongli Cui, Sen Cheng, Xiaoyun Liu, Jie Lu, Jing Tao, Yu-Feng Yao
HilD, a dominant regulator of Salmonella pathogenicity island 1 (SPI-1), can be acetylated by acetyltransferase Pat in Salmonella Typhimurium, and the acetylation is beneficial to its stability. However, the underlying mechanism of HilD stability regulated by acetylation is not clear. We show here that lysine 297 (K297) located in the helix-turn-helix motif, can be acetylated by Pat. Acetylation of K297 increases HilD stability, but reduces its DNA-binding affinity. In turn, the deacetylated K297 enhances the DNA-binding ability, but decreases HilD stability...
February 24, 2017: Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28329127/listeria-monocytogenes-cadc-regulates-cadmium-efflux-and-fine-tunes-lipoprotein-localization-to-escape-the-host-immune-response-and-promote-infection
#18
Rita Pombinho, Ana Camejo, Ana Vieira, Olga Reis, Filipe Carvalho, Maria Teresa Almeida, Jorge Campos Pinheiro, Sandra Sousa, Didier Cabanes
Listeria monocytogenes (Lm) is a major intracellular human foodborne bacterial pathogen. We previously revealed Lm-cadC as highly expressed during mouse infection. Here we show that Lm-CadC is a sequence-specific, DNA-binding and cadmium-dependent regulator of CadA, an efflux pump conferring cadmium resistance. CadC, but not CadA, is required for Lm infection in vivo. Interestingly, CadC also directly represses lspB, a gene encoding a lipoprotein signal peptidase whose expression appears detrimental for infection...
March 9, 2017: Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28328921/versatile-modes-of-cellular-regulation-via-cyclic-dinucleotides
#19
REVIEW
Petya Violinova Krasteva, Holger Sondermann
Since the discovery of c-di-GMP almost three decades ago, cyclic dinucleotides (CDNs) have emerged as widely used signaling molecules in most kingdoms of life. The family of second messengers now includes c-di-AMP and distinct versions of mixed cyclic GMP-AMP (cGAMP) compounds. In addition to these nucleotides, a vast number of proteins for the production and turnover of these molecules have been described, as well as effectors that translate the signals into physiological responses. The latter include, but are not limited to, mechanisms for adaptation and survival in prokaryotes, persistence and virulence of bacterial pathogens, and immune responses to viral and bacterial invasion in eukaryotes...
March 22, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28326294/the-eukaryote-like-serine-threonine-kinase-stk-regulates-the-growth-and-metabolism-of-zoonotic-streptococcus-suis
#20
Chunyan Zhang, Wen Sun, Meifang Tan, Mengmeng Dong, Wanquan Liu, Ting Gao, Lu Li, Zhuofei Xu, Rui Zhou
Like eukaryotes, bacteria express one or more serine/threonine kinases (STKs) that initiate diverse signaling networks. The STK from Streptococcus suis is encoded by a single-copy stk gene, which is crucial in stress response and virulence. To further understand the regulatory mechanism of STK in S. suis, a stk deletion strain (Δstk) and its complementary strain (CΔstk) were constructed to systematically decode STK characteristics by applying whole transcriptome RNA sequencing (RNA-Seq) and phosphoproteomic analysis...
2017: Frontiers in Cellular and Infection Microbiology
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