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https://www.readbyqxmd.com/read/28536292/capsule-production-and-glucose-metabolism-dictate-fitness-during-serratia-marcescens-bacteremia
#1
Mark T Anderson, Lindsay A Mitchell, Lili Zhao, Harry L T Mobley
Serratia marcescens is an opportunistic pathogen that causes a range of human infections, including bacteremia, keratitis, wound infections, and urinary tract infections. Compared to other members of the Enterobacteriaceae family, the genetic factors that facilitate Serratia proliferation within the mammalian host are less well defined. An in vivo screen of transposon insertion mutants identified 212 S. marcescens fitness genes that contribute to bacterial survival in a murine model of bloodstream infection...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28536291/evolution-of-bacterial-frenemies
#2
Sophie E Darch, Carolyn B Ibberson, Marvin Whiteley
Chronic polymicrobial infections are associated with increased virulence compared to monospecies infections. However, our understanding of microbial dynamics during polymicrobial infection is limited. A recent study by Limoli and colleagues (D. H. Limoli, G. B. Whitfield, T. Kitao, M. L. Ivey, M. R. Davis, Jr., et al., mBio 8:e00186-17, 2017, https://doi.org/10.1128/mBio.00186-17) provides insight into a mechanism that may contribute to the coexistence of Pseudomonas aeruginosa and Staphylococcus aureus in the cystic fibrosis (CF) lung...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28536290/peptidoglycan-association-of-murein-lipoprotein-is-required-for-kpsd-dependent-group-2-capsular-polysaccharide-expression-and-serum-resistance-in-a-uropathogenic-escherichia-coli-isolate
#3
Jingyu Diao, Catrien Bouwman, Donghong Yan, Jing Kang, Anand K Katakam, Peter Liu, Homer Pantua, Alexander R Abbas, Nicholas N Nickerson, Cary Austin, Mike Reichelt, Wendy Sandoval, Min Xu, Chris Whitfield, Sharookh B Kapadia
Murein lipoprotein (Lpp) and peptidoglycan-associated lipoprotein (Pal) are major outer membrane lipoproteins in Escherichia coli Their roles in cell-envelope integrity have been documented in E. coli laboratory strains, and while Lpp has been linked to serum resistance in vitro, the underlying mechanism has not been established. Here, lpp and pal mutants of uropathogenic E. coli strain CFT073 showed reduced survival in a mouse bacteremia model, but only the lpp mutant was sensitive to serum killing in vitro The peptidoglycan-bound Lpp form was specifically required for preventing complement-mediated bacterial lysis in vitro and complement-mediated clearance in vivo Compared to the wild-type strain, the lpp mutant had impaired K2 capsular polysaccharide production and was unable to respond to exposure to serum by elevating capsular polysaccharide amounts...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28536289/modulation-of-aneuploidy-in-leishmania-donovani-during-adaptation-to-different-in-vitro-and-in-vivo-environments-and-its-impact-on-gene-expression
#4
F Dumetz, H Imamura, M Sanders, V Seblova, J Myskova, P Pescher, M Vanaerschot, C J Meehan, B Cuypers, G De Muylder, G F Späth, G Bussotti, J R Vermeesch, M Berriman, J A Cotton, P Volf, J C Dujardin, M A Domagalska
Aneuploidy is usually deleterious in multicellular organisms but appears to be tolerated and potentially beneficial in unicellular organisms, including pathogens. Leishmania, a major protozoan parasite, is emerging as a new model for aneuploidy, since in vitro-cultivated strains are highly aneuploid, with interstrain diversity and intrastrain mosaicism. The alternation of two life stages in different environments (extracellular promastigotes and intracellular amastigotes) offers a unique opportunity to study the impact of environment on aneuploidy and gene expression...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28536288/cnot4-mediated-ubiquitination-of-influenza-a-virus-nucleoprotein-promotes-viral-rna-replication
#5
Yu-Chen Lin, King-Song Jeng, Michael M C Lai
Influenza A virus (IAV) RNA segments are individually packaged with viral nucleoprotein (NP) and RNA polymerases to form a viral ribonucleoprotein (vRNP) complex. We previously reported that NP is a monoubiquitinated protein which can be deubiquitinated by a cellular ubiquitin protease, USP11. In this study, we identified an E3 ubiquitin ligase, CNOT4 (Ccr4-Not transcription complex subunit 4), which can ubiquitinate NP. We found that the levels of viral RNA, protein, viral particles, and RNA polymerase activity in CNOT4 knockdown cells were lower than those in the control cells upon IAV infection...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28536287/kisameet-glacial-clay-an-unexpected-source-of-bacterial-diversity
#6
Sarah L Svensson, Shekooh Behroozian, Wanjing Xu, Michael G Surette, Loretta Li, Julian Davies
Widespread antibiotic resistance among bacterial pathogens is providing the impetus to explore novel sources of antimicrobial agents. Recently, the potent antibacterial activity of certain clay minerals has stimulated scientific interest in these materials. One such example is Kisameet glacial clay (KC), an antibacterial clay from a deposit on the central coast of British Columbia, Canada. However, our understanding of the active principles of these complex natural substances is incomplete. Like soils, clays may possess complex mixtures of bacterial taxa, including the Actinobacteria, a clade known to be rich in antibiotic-producing organisms...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28536286/mutations-that-alter-the-bacterial-cell-envelope-increase-lipid-production
#7
Kimberly C Lemmer, Weiping Zhang, Samantha J Langer, Alice C Dohnalkova, Dehong Hu, Rachelle A Lemke, Jeff S Piotrowski, Galya Orr, Daniel R Noguera, Timothy J Donohue
Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation in Rhodobacter sphaeroides By screening an R. sphaeroides Tn5 mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their total lipids extracellularly...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28536285/gut-microbiota-mediates-the-protective-effects-of-dietary-capsaicin-against-chronic-low-grade-inflammation-and-associated-obesity-induced-by-high-fat-diet
#8
Chao Kang, Bin Wang, Kanakaraju Kaliannan, Xiaolan Wang, Hedong Lang, Suocheng Hui, Li Huang, Yong Zhang, Ming Zhou, Mengting Chen, Mantian Mi
Metabolic endotoxemia originating from dysbiotic gut microbiota has been identified as a primary mediator for triggering the chronic low-grade inflammation (CLGI) responsible for the development of obesity. Capsaicin (CAP) is the major pungent bioactivator in chili peppers and has potent anti-obesity functions, yet the mechanisms linking this effect to gut microbiota remain obscure. Here we show that mice fed a high-fat diet (HFD) supplemented with CAP exhibit lower levels of metabolic endotoxemia and CLGI associated with lower body weight gain...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28536284/preprinting-microbiology
#9
Patrick D Schloss
The field of microbiology has experienced significant growth due to transformative advances in technology and the influx of scientists driven by a curiosity to understand how microbes sustain myriad biochemical processes that maintain Earth. With this explosion in scientific output, a significant bottleneck has been the ability to rapidly disseminate new knowledge to peers and the public. Preprints have emerged as a tool that a growing number of microbiologists are using to overcome this bottleneck. Posting preprints can help to transparently recruit a more diverse pool of reviewers prior to submitting to a journal for formal peer review...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28536283/signal-integration-in-quorum-sensing-enables-cross-species-induction-of-virulence-in-pectobacterium-wasabiae
#10
Rita S Valente, Pol Nadal-Jimenez, André F P Carvalho, Filipe J D Vieira, Karina B Xavier
Bacterial communities can sense their neighbors, regulating group behaviors in response to cell density and environmental changes. The diversity of signaling networks in a single species has been postulated to allow custom responses to different stimuli; however, little is known about how multiple signals are integrated and the implications of this integration in different ecological contexts. In the plant pathogen Pectobacterium wasabiae (formerly Erwinia carotovora), two signaling networks-the N-acyl homoserine lactone (AHL) quorum-sensing system and the Gac/Rsm signal transduction pathway-control the expression of secreted plant cell wall-degrading enzymes, its major virulence determinants...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28512097/glutathionylation-of-yersinia-pestis-lcrv-and-its-effects-on-plague-pathogenesis
#11
Anthony Mitchell, Christina Tam, Derek Elli, Thomas Charlton, Patrick Osei-Owusu, Farbod Fazlollahi, Kym F Faull, Olaf Schneewind
Glutathionylation, the formation of reversible mixed disulfides between glutathione and protein cysteine residues, is a posttranslational modification previously observed for intracellular proteins of bacteria. Here we show that Yersinia pestis LcrV, a secreted protein capping the type III secretion machine, is glutathionylated at Cys(273) and that this modification promotes association with host ribosomal protein S3 (RPS3), moderates Y. pestis type III effector transport and killing of macrophages, and enhances bubonic plague pathogenesis in mice and rats...
May 16, 2017: MBio
https://www.readbyqxmd.com/read/28512096/erratum-for-briese-et-al-virome-capture-sequencing-enables-sensitive-viral-diagnosis-and-comprehensive-virome-analysis
#12
Thomas Briese, Amit Kapoor, Nischay Mishra, Komal Jain, Arvind Kumar, Omar J Jabado, W Ian Lipkin
No abstract text is available yet for this article.
May 16, 2017: MBio
https://www.readbyqxmd.com/read/28512095/structure-based-mutations-in-the-herpes-simplex-virus-1-glycoprotein-b-ectodomain-arm-impart-a-slow-entry-phenotype
#13
Qing Fan, Sarah J Kopp, Sarah A Connolly, Richard Longnecker
Glycoprotein B (gB) is the conserved herpesvirus fusion protein, and it is required for the entry of herpesviruses. The structure of the postfusion conformation of gB has been solved for several herpesviruses; however, the gB prefusion crystal structure and the details of how the protein refolds from a prefusion to a postfusion form to mediate fusion have not been determined. Using structure-based mutagenesis, we previously reported that three mutations (I671A, H681A, and F683A) in the C-terminal arm of the gB ectodomain greatly reduced cell-cell fusion...
May 16, 2017: MBio
https://www.readbyqxmd.com/read/28512094/intrinsic-toxin-derived-peptides-destabilize-and-inactivate-clostridium-difficile-tcdb
#14
Jason L Larabee, Sarah J Bland, Jonathan J Hunt, Jimmy D Ballard
Clostridium difficile infection (CDI) is a major cause of hospital-associated, antibiotic-induced diarrhea, which is largely mediated by the production of two large multidomain clostridial toxins, TcdA and TcdB. Both toxins coordinate the action of specific domains to bind receptors, enter cells, and deliver a catalytic fragment into the cytosol. This results in GTPase inactivation, actin disassembly, and cytotoxicity. TcdB in particular has been shown to encode a region covering amino acids 1753 to 1851 that affects epitope exposure and cytotoxicity...
May 16, 2017: MBio
https://www.readbyqxmd.com/read/28512093/population-genomic-analysis-of-1-777-extended-spectrum-beta-lactamase-producing-klebsiella-pneumoniae-isolates-houston-texas-unexpected-abundance-of-clonal-group-307
#15
S Wesley Long, Randall J Olsen, Todd N Eagar, Stephen B Beres, Picheng Zhao, James J Davis, Thomas Brettin, Fangfang Xia, James M Musser
Klebsiella pneumoniae is a major human pathogen responsible for high morbidity and mortality rates. The emergence and spread of strains resistant to multiple antimicrobial agents and documented large nosocomial outbreaks are especially concerning. To develop new therapeutic strategies for K. pneumoniae, it is imperative to understand the population genomic structure of strains causing human infections. To address this knowledge gap, we sequenced the genomes of 1,777 extended-spectrum beta-lactamase-producing K...
May 16, 2017: MBio
https://www.readbyqxmd.com/read/28512092/quantitative-kinetic-analyses-of-shutting-off-a-two-component-system
#16
Rong Gao, Ann M Stock
Cells rely on accurate control of signaling systems to adapt to environmental perturbations. System deactivation upon stimulus removal is as important as activation of signaling pathways. The two-component system (TCS) is one of the major bacterial signaling schemes. In many TCSs, phosphatase activity of the histidine kinase (HK) is believed to play an essential role in shutting off the pathway and resetting the system to the prestimulus state. Two basic challenges are to understand the dynamic behavior of system deactivation and to quantitatively evaluate the role of phosphatase activity under natural cellular conditions...
May 16, 2017: MBio
https://www.readbyqxmd.com/read/28512091/conformational-flexibility-in-the-immunoglobulin-like-domain-of-the-hepatitis-c-virus-glycoprotein-e2
#17
Ieva Vasiliauskaite, Ania Owsianka, Patrick England, Abdul Ghafoor Khan, Sarah Cole, Dorothea Bankwitz, Steven K H Foung, Thomas Pietschmann, Joseph Marcotrigiano, Felix A Rey, Arvind H Patel, Thomas Krey
The hepatitis C virus (HCV) glycoprotein E2 is the major target of neutralizing antibodies and is therefore highly relevant for vaccine design. Its structure features a central immunoglobulin (Ig)-like β-sandwich that contributes to the binding site for the cellular receptor CD81. We show that a synthetic peptide corresponding to a β-strand of this Ig-like domain forms an α-helix in complex with the anti-E2 antibody DAO5, demonstrating an inside-out flip of hydrophobic residues and a secondary structure change in the composite CD81 binding site...
May 16, 2017: MBio
https://www.readbyqxmd.com/read/28512090/the-vibrio-cholerae-vexgh-rnd-efflux-system-maintains-cellular-homeostasis-by-effluxing-vibriobactin
#18
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/28487432/deciphering-mcr-2-colistin-resistance
#19
Jian Sun, Yongchang Xu, Rongsui Gao, Jingxia Lin, Wenhui Wei, Swaminath Srinivas, Defeng Li, Run-Shi Yang, Xing-Ping Li, Xiao-Ping Liao, Ya-Hong Liu, Youjun Feng
Antibiotic resistance is a prevalent problem in public health worldwide. In general, the carbapenem β-lactam antibiotics are considered a final resort against lethal infections by multidrug-resistant bacteria. Colistin is a cationic polypeptide antibiotic and acts as the last line of defense for treatment of carbapenem-resistant bacteria. Very recently, a new plasmid-borne colistin resistance gene, mcr-2, was revealed soon after the discovery of the paradigm gene mcr-1, which has disseminated globally. However, the molecular mechanisms for MCR-2 colistin resistance are poorly understood...
May 9, 2017: MBio
https://www.readbyqxmd.com/read/28487431/different-roles-of-mitochondrial-calcium-uniporter-complex-subunits-in-growth-and-infectivity-of-trypanosoma-cruzi
#20
Miguel A Chiurillo, Noelia Lander, Mayara S Bertolini, Melissa Storey, Anibal E Vercesi, Roberto Docampo
Trypanosoma cruzi is the agent of Chagas disease, and the finding that this parasite possesses a mitochondrial calcium uniporter (TcMCU) with characteristics similar to that of mammalian mitochondria was fundamental for the discovery of the molecular nature of MCU in eukaryotes. We report here that ablation of TcMCU, or its paralog TcMCUb, by clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 led to a marked decrease in mitochondrial Ca(2+) uptake without affecting the membrane potential of these cells, whereas overexpression of each gene caused a significant increase in the ability of mitochondria to accumulate Ca(2+) While TcMCU-knockout (KO) epimastigotes were viable and able to differentiate into trypomastigotes, infect host cells, and replicate normally, ablation of TcMCUb resulted in epimastigotes having an important growth defect, lower rates of respiration and metacyclogenesis, more pronounced autophagy changes under starvation, and significantly reduced infectivity...
May 9, 2017: MBio
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