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Journal of Bacteriology

C J Kovacs, R C Faustoferri, R G Quivey
Bacterial cell wall dynamics have been implicated as important determinants of cellular physiology, stress tolerance and virulence. In Streptococcus mutans, the cell wall is composed primarily of a rhamnose-glucose polysaccharide (RGP) linked to the peptidoglycan. Despite extensive studies describing its formation and composition, the potential roles for RGP in S. mutans biology have not been well investigated. The present study characterizes the impact of RGP disruption as a result of deletion of rgpF, the gene encoding a rhamnosyltransferase involved in construction of the core poly-rhamnose backbone of RGP...
September 18, 2017: Journal of Bacteriology
William E Sause, Richard Copin, Aidan O'malley, Rita Chan, Brian J Morrow, Peter T Buckley, Jeffrey Fernandez, A Simon Lynch, Bo Shopsin, Victor J Torres
Staphylococcus aureus is a major human pathogen that imposes a great burden on the healthcare system. In the development of anti-staphylococcal modalities intended to reduce the burden of staphylococcal disease, it is imperative to select appropriate models of S. aureus strains when assessing the efficacy of novel agents. Here, using whole genome sequencing, we reveal that the commonly used strain Newman D2C from the American Type Culture Collection (ATCC) contains mutations that render the strain essentially avirulent...
September 18, 2017: Journal of Bacteriology
Luke A Fenlon, James M Slauch
Salmonella Typhimurium is a leading cause of foodborne disease worldwide. Severe infections result from the ability of S. Typhimurium to survive within host immune cells, despite being exposed to various host antimicrobial factors. SodCI, a copper-zinc cofactored superoxide dismutase, is required to defend against phagocytic superoxide. SodCII, an additional periplasmic superoxide dismutase, although produced during infection, does not function in the host. Previous studies suggested that CueP, a periplasmic copper binding protein, facilitates acquisition of copper by SodCII...
September 18, 2017: Journal of Bacteriology
Sébastien Crépin, Gaëlle Porcheron, Sébastien Houle, Josée Harel, Charles M Dozois
The pst gene cluster encodes the phosphate specific transport system (Pst). Inactivation of the Pst system constitutively activates the two-component regulatory system PhoBR and attenuates virulence of pathogenic bacteria. In uropathogenic E. coli strain CFT073, attenuation by inactivation of pst is predominantly attributed to the decreased expression of type 1 fimbriae. However, the molecular mechanisms connecting the Pst system and type 1 fimbriae are unknown. To address this, a transposon library was constructed in the pst mutant, and clones were tested for a regain in type 1 fimbriae production...
September 18, 2017: Journal of Bacteriology
Helen Yakhnin, Robert Aichele, Sarah E Ades, Tony Romeo, Paul Babitzke
CsrA of Escherichia coli is an RNA-binding protein that globally regulates a wide variety of cellular processes and behaviors including carbon metabolism, motility, biofilm formation, and the stringent response. CsrB and CsrC are sRNAs that sequester CsrA, thereby preventing CsrA-mRNA interaction. RpoE (σ(E)) is the extracytoplasmic stress response sigma factor of E. coli Previous RNA-seq studies identified rpoE mRNA as a CsrA target. Here we explored the regulation of rpoE by CsrA and found that CsrA represses rpoE translation...
September 18, 2017: Journal of Bacteriology
Michal Burmistrz, Jose Ignacio Rodriguez Martinez, Daniel Krochmal, Dominika Staniec, Krzysztof Pyrc
The CRISPR-Cas (clustered regularly interspaced short palindromic repeats - CRISPR associated) system is unique to prokaryotes and provides the majority of bacteria and archaea with immunity against nucleic acids of foreign origin. crRNAs are the key element of this system, since they are responsible for its selectivity and effectiveness. Typical crRNAs consist of a spacer sequence flanked with 5' and 3' handles originating from repeat sequences that are important for recognition of these small RNAs by the Cas machinery...
September 11, 2017: Journal of Bacteriology
Khaled A Aly, Mark Anderson, Ryan Jay Ohr, Dominique Missiakas
The ESAT6-like secretion system (ESS) of Staphylococcus aureus promotes effector protein transport across the bacterial envelope. Genes in the ESS cluster are required for S. aureus establishment of persistent abscess lesions and the modulation of immune responses during blood stream infections. The biochemical functions of most of the ESS gene products, specifically the identity of secretion machine components, are however unknown. Earlier work demonstrated that deletion of essB, which encodes a membrane protein, abolishes S...
September 5, 2017: Journal of Bacteriology
Celia Méndez-García, Coral Barbas, Manuel Ferrer, David Rojo
In 1680, Antonie van Leewenhoek noted compositional differences in his oral and fecal microbiota, pioneering the study of the diversity of the human microbiome. From Leewenhoek to modern successful attempts of changing the gut microbiota landscape to cure disease, there has been an exponential increase in the recognition of our resident microbes as part of ourselves. Thus, the human host and microbiome have evolved in parallel to configure a balanced system in which microbes survive in homeostasis with our innate and acquired immune system, unless disease occurs...
September 5, 2017: Journal of Bacteriology
L Zeng, E Wooton, D A Stahl, P J Walian
Due in large part to their ability to facilitate the diffusion of a diverse range of solutes across the outer membrane (OM) of Gram-negative bacteria, the porins represent one of the most prominent and important bacterial membrane protein superfamilies. Notably, for the Gram-negative bacterium Desulfovibrio vulgaris Hildenborough (DvH), a model organism for studies of sulfate-reducing bacteria, no porins have been identified or proposed in its annotated genome. Results from initial biochemical studies suggested that the product of gene DVU0799, one of the most abundant proteins of the DvH OM and purified as a homotrimeric complex, was a strong porin candidate...
September 5, 2017: Journal of Bacteriology
Dušanka Djorić, Christopher J Kristich
Enterococci are major causes of hospital-acquired infections. Intrinsic resistance to cephalosporins is a universal trait among clinically relevant enterococci. Cephalosporin resistance enables enterococci to proliferate to high densities in the intestines of patients undergoing cephalosporin treatment, a precursor to the emergence of infection. However, the genetic and biochemical mechanisms of intrinsic cephalosporin resistance in enterococci are not well understood. A two-component signal transduction system, CroR/S, is required for cephalosporin resistance in enterococci...
September 5, 2017: Journal of Bacteriology
Brad K Kern, Eric A Porsch, Joseph W St Geme
Kingella kingae is an important pathogen in young children and initiates infection by colonizing the posterior pharynx. Adherence to pharyngeal epithelial cells is an important first step in the process of colonization. In the present study, we sought to elucidate the interplay of type IV pili (T4P), a trimeric autotransporter adhesin called Knh, and the polysaccharide capsule in K. kingae adherence to host cells. Using adherence assays performed under shear stress, we observed that a strain expressing only Knh was capable of higher levels of adherence than a strain expressing only T4P...
September 5, 2017: Journal of Bacteriology
Matthew J Reichlen, Rachel L Leistikow, Micah S Scobey, Sarah E M Born, Martin I Voskuil
Mycobacterium tuberculosis (Mtb) is a strict aerobe capable of prolonged survival in the absence of oxygen. We investigated the ability of anaerobic Mtb to counter challenges to internal pH homeostasis in the absence of aerobic respiration, the primary mechanism of proton efflux for aerobic bacilli. Anaerobic Mtb populations were markedly impaired for survival under a mildly acidic pH relative to standard culture conditions. Acidic environmental pH greatly increased the susceptibility of anaerobic bacilli to collapse of proton motive force by protonophores, to antimicrobial compounds that target entry into the electron transport system, and to small organic acids with uncoupling activity...
September 5, 2017: Journal of Bacteriology
Yuzo Kevorkian, Aimee Shen
Clostridium difficile causes considerable healthcare-associated gastrointestinal disease that is transmitted by its metabolically dormant spore form. Upon entering the gut, C. difficile spores germinate and outgrow to produce vegetative cells that release disease-causing toxins. C. difficile spore germination depends on the Csp family of (pseudo)proteases and the cortex hydrolase, SleC. The CspC pseudoprotease functions as a bile salt germinant receptor that activates the protease CspB, which in turn proteolytically activates SleC zymogen...
September 5, 2017: Journal of Bacteriology
Shubham Chakravarty, Cameron N Melton, Adam Bailin, Timothy L Yahr, Gregory G Anderson
Pseudomonas aeruginosa causes numerous acute and chronic opportunistic infections in humans. One of its most formidable weapons is a type III secretion system (T3SS), which injects powerful toxins directly into host cells. The toxins lead to cell dysfunction and, ultimately, cell death. Identification of regulatory pathways that control T3SS gene expression may lead to the discovery of novel therapeutics to treat P. aeruginosa infections. In a previous study, we found that expression of the magnesium transporter gene mgtE inhibits T3SS gene transcription...
August 28, 2017: Journal of Bacteriology
Martina Pasqua, Daniela Visaggio, Alessandra Lo Sciuto, Shirley Genah, Ehud Banin, Paolo Visca, Francesco Imperi
In Pseudomonas aeruginosa the ferric uptake regulator protein (Fur) controls both metabolism and virulence in response to iron availability. Differently from other bacteria, attempts to obtain fur deletion mutants in P. aeruginosa failed, leading to the assumption that Fur is an essential protein in this bacterium. By investigating a P. aeruginosa fur conditional mutant, we demonstrate that Fur is not essential for P. aeruginosa growth in liquid media, biofilm formation, and pathogenicity in an insect model of infection...
August 28, 2017: Journal of Bacteriology
Özhan Özkaya, Karina B Xavier, Francisco Dionisio, Roberto Balbontín
Microbes often form densely populated communities, which favor competitive and cooperative interactions. Cooperation among bacteria often occurs through the production of metabolically costly molecules produced by certain individuals that become available to other neighboring individuals, called public goods. This type of cooperation is susceptible to exploitation, since non-producers of a public good can benefit from it while saving the cost of its production (cheating), gaining a fitness advantage over producers (cooperators)...
August 28, 2017: Journal of Bacteriology
Tianyi Jiang, Xiaoting Guo, Jinxin Yan, Yingxin Zhang, Yujiao Wang, Manman Zhang, Binbin Sheng, Cuiqing Ma, Ping Xu, Chao Gao
Bacterial membrane-associated NAD-independent d-lactate dehydrogenase (Fe-S d-iLDH) oxidizes d-lactate into pyruvate. Sequence analysis of the enzyme reveals that it contains a Fe-S oxidoreductase domain in addition to an FAD-containing dehydrogenase domain, which differs from other typical d-iLDHs. Fe-S d-iLDH from Pseudomonas putida KT2440 was purified as a His-tagged protein and characterized in detail. This monomeric enzyme exhibited activities with l-lactate and several d-2-hydroxyacids. Quinone was shown to be the preferred electron acceptor of the enzyme...
August 28, 2017: Journal of Bacteriology
Anice Sabag-Daigle, Anindita Sengupta, Henry M Blunk, Pradip K Biswas, Mary Claire Cron, Alexander Bogard, Edward J Behrman, Venkat Gopalan, Brian M M Ahmer
Salmonella enterica can utilize fructose-asparagine (F-Asn) as a carbon and nitrogen source. This unusual capability has been attributed to five genes in the fra locus. Previously, we determined that mutations in fraB (deglycase), fraD (kinase), or fraA (transporter) eliminated the ability of Salmonella to grow on F-Asn while a mutation in fraE allowed partial growth. We hypothesized that FraE, a putative periplasmic fructose-asparaginase, converts F-Asn to NH4(+) and fructose-aspartate (F-Asp). FraA could then transport F-Asp into the cytoplasm for subsequent catabolism...
August 28, 2017: Journal of Bacteriology
Steven Higgins, Maria Sanchez-Contreras, Stefano Gualdi, Marta Pinto-Carbó, Aurélien Carlier, Leo Eberl
The study of the minimum set of genes required to sustain life is a fundamental question in biological research. Recent studies on bacterial essential genes suggested that between 350 and 700 genes are essential to support autonomous bacterial cell growth. Essential genes are of interest as potential new antimicrobial drug targets and hence, our aim was to identify the essential genome of the cystic fibrosis (CF) isolate Burkholderia cenocepacia H111. Using a Tn-Seq approach we identified essential genes required for growth in rich medium under aerobic and micro-oxic conditions as well as in a defined minimal medium with citrate as a sole carbon source...
August 28, 2017: Journal of Bacteriology
Qing Chen, Victoria Ng, Jason M Warfel, Tod J Merkel, Scott Stibitz
The two-component response regulator RisA, encoded by BP3554 in the Bordetella pertussis Tohama I genomic sequence, is a known activator of vrgs, a set of genes whose expression is increased under the same environmental conditions (known as modulation) that result in repression of the bvgAS virulence regulon. Here we demonstrate that RisA is phosphorylated in vivo and that RisA phosphorylation is required for activation of vrgs. An adjacent histidine kinase gene, risS, is truncated by frameshift mutation in B...
August 21, 2017: Journal of Bacteriology
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