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Katharina Kitzinger, Hanna Koch, Sebastian Lücker, Christopher J Sedlacek, Craig Herbold, Jasmin Schwarz, Anne Daebeler, Anna J Mueller, Michael Lukumbuzya, Stefano Romano, Nikolaus Leisch, Søren Michael Karst, Rasmus Kirkegaard, Mads Albertsen, Per Halkjær Nielsen, Michael Wagner, Holger Daims
Nitrification is a key process of the biogeochemical nitrogen cycle and of biological wastewater treatment. The second step, nitrite oxidation to nitrate, is catalyzed by phylogenetically diverse, chemolithoautotrophic nitrite-oxidizing bacteria (NOB). Uncultured NOB from the genus " Candidatus Nitrotoga" are widespread in natural and engineered ecosystems. Knowledge about their biology is sparse, because no genomic information and no pure " Ca Nitrotoga" culture was available. Here we obtained the first " Ca Nitrotoga" isolate from activated sludge...
July 10, 2018: MBio
James L Coleman, Alvaro Toledo, Jorge L Benach
Borrelia burgdorferi HtrA (HtrABb) is a serine protease that targets damaged or improperly folded proteins. In our previous studies, HtrABb specifically degraded basic membrane protein BmpD, chemotaxis phosphatase CheX, and outer membrane protein P66. In addition, HtrABb degrades virulence factor BB0323 and components of the extracellular matrix fibronectin and aggrecan. A proteomics-based analysis (two-dimensional difference gel electrophoresis [2-D DIGE], liquid chromatography-mass spectrometry [LC-MS]) of an HtrABb-overexpressing strain of B...
July 10, 2018: MBio
Jainaba Manneh-Roussel, James R J Haycocks, Andrés Magán, Nicolas Perez-Soto, Kerstin Voelz, Andrew Camilli, Anne-Marie Krachler, David C Grainger
The bacterium Vibrio cholerae is native to aquatic environments and can switch lifestyles to cause disease in humans. Lifestyle switching requires modulation of genetic systems for quorum sensing, intestinal colonization, and toxin production. Much of this regulation occurs at the level of gene expression and is controlled by transcription factors. In this work, we have mapped the binding of cAMP receptor protein (CRP) and RNA polymerase across the V. cholerae genome. We show that CRP is an integral component of the regulatory network that controls lifestyle switching...
July 10, 2018: MBio
Peter C Dumoulin, Barbara A Burleigh
The mammalian stages of the parasite Trypanosoma cruzi , the causative agent of Chagas disease, exhibit a wide host species range and extensive within-host tissue distribution. These features, coupled with the ability of the parasites to persist for the lifetime of the host, suggest an inherent capacity to tolerate changing environments. To examine this potential, we studied proliferation and cell cycle dynamics of intracellular T. cruzi amastigotes experiencing transient metabolic perturbation or drug pressure in the context of an infected mammalian host cell...
July 10, 2018: MBio
Cheng Yuan, Sondra G Lazarowitz, Vitaly Citovsky
Plant viruses cross the barrier of the plant cell wall by moving through intercellular channels, termed plasmodesmata, to invade their hosts. They accomplish this by encoding movement proteins (MPs), which act to alter plasmodesmal gating. How MPs target to plasmodesmata is not well understood. Our recent characterization of the first plasmodesmal localization signal (PLS) identified in a viral MP, namely, the MP encoded by the Tobamovirus Tobacco mosaic virus (TMV), now provides the opportunity to identify host proteins that recognize this PLS and may be important for its plasmodesmal targeting...
July 10, 2018: MBio
Patrick M Ketter, Jieh-Juen Yu, M Neal Guentzel, Holly C May, Rishein Gupta, Mark Eppinger, Karl E Klose, J Seshu, James P Chambers, Andrew P Cap, Bernard P Arulanandam
Multidrug-resistant Acinetobacter baumannii is among the most common causes of infectious complications associated with combat-related trauma in military personnel serving overseas. However, little is currently known about its pathogenesis. While the gastrointestinal (GI) tract has been found to be a major reservoir for A. baumannii , as well as to potentially contribute to development of multidrug resistance, no studies have addressed the mechanisms involved in gut colonization. In this study, we address this critical gap in knowledge by first assessing the interaction between secretory IgA (SIgA), the principal humoral immune defense on mucosal surfaces, and the A...
July 10, 2018: MBio
Toshiyuki Ueki, Kelly P Nevin, Amelia-Elena Rotaru, Li-Ying Wang, Joy E Ward, Trevor L Woodard, Derek R Lovley
Cytochrome-to-cytochrome electron transfer and electron transfer along conduits of multiple extracellular magnetite grains are often proposed as strategies for direct interspecies electron transfer (DIET) that do not require electrically conductive pili (e-pili). However, physical evidence for these proposed DIET mechanisms has been lacking. To investigate these possibilities further, we constructed Geobacter metallireducens strain Aro-5, in which the wild-type pilin gene was replaced with the aro-5 pilin gene that was previously shown to yield poorly conductive pili in Geobacter sulfurreducens strain Aro-5...
July 10, 2018: MBio
David Giacalone, T Jarrod Smith, Alan J Collins, Holger Sondermann, Lori J Koziol, George A O'Toole
The bacterial intracellular second messenger, cyclic dimeric GMP (c-di-GMP), regulates biofilm formation for many bacteria. The binding of c-di-GMP by the inner membrane protein LapD controls biofilm formation, and the LapD receptor is central to a complex network of c-di-GMP-mediated biofilm formation. In this study, we examine how c-di-GMP signaling specificity by a diguanylate cyclase (DGC), GcbC, is achieved via interactions with the LapD receptor and by small ligand sensing via GcbC's <u>ca</u>lcium channel <u>che</u>motaxis (CACHE) domain...
July 10, 2018: MBio
Gargi Kulkarni, Thomas D Mand, William W Metcalf
Energy conservation via hydrogen cycling, which generates proton motive force by intracellular H2 production coupled to extracellular consumption, has been controversial since it was first proposed in 1981. It was hypothesized that the methanogenic archaeon Methanosarcina barkeri is capable of energy conservation via H2 cycling, based on genetic data that suggest that H2 is a preferred, but nonessential, intermediate in the electron transport chain of this organism. Here, we characterize a series of hydrogenase mutants to provide direct evidence of H2 cycling...
July 3, 2018: MBio
Bartram L Smith, Guifang Chen, Claus O Wilke, Robert M Krug
Influenza A viruses cause an annual contagious respiratory disease in humans and are responsible for periodic high-mortality human pandemics. Pandemic influenza A viruses usually result from the reassortment of gene segments between human and avian influenza viruses. These avian influenza virus gene segments need to adapt to humans. Here we focus on the human adaptation of the synonymous codons of the avian influenza virus PB1 gene of the 1968 H3N2 pandemic virus. We generated recombinant H3N2 viruses differing only in codon usage of PB1 mRNA and demonstrated that codon usage of the PB1 mRNA of recent H3N2 virus isolates enhances replication in interferon (IFN)-treated human cells without affecting replication in untreated cells, thereby partially alleviating the interferon-induced antiviral state...
July 3, 2018: MBio
Alexander Shulman, Yael Yair, Dvora Biran, Thomas Sura, Andreas Otto, Uri Gophna, Dörte Becher, Michael Hecker, Eliora Z Ron
Many strains of Escherichia coli carry a 29,250-bp ETT2 pathogenicity island (PAI), which includes genes predicted to encode type III secretion system (T3SS) components. Because it is similar to the Salmonella pathogenicity island 1 (SPI-1) system, encoding a T3SS in Salmonella enterica , it was assumed that ETT2 also encodes a secretion system injecting effectors into host cells. This assumption was checked in E. coli serotype O2-associated with urinary tract infections and septicemia-which has an intact ETT2 gene cluster, in contrast to most strains in which this cluster carries deletions and mutations...
July 3, 2018: MBio
Andrea M Lencina, Thierry Franza, Matthew J Sullivan, Glen C Ulett, Deepak S Ipe, Philippe Gaudu, Robert B Gennis, Lici A Schurig-Briccio
The opportunistic pathogen Streptococcus agalactiae is the major cause of meningitis and sepsis in a newborn's first week, as well as a considerable cause of pneumonia, urinary tract infections, and sepsis in immunocompromised adults. This pathogen respires aerobically if heme and quinone are available in the environment, and a functional respiratory chain is required for full virulence. Remarkably, it is shown here that the entire respiratory chain of S. agalactiae consists of only two enzymes, a type 2 NADH dehydrogenase (NDH-2) and a cytochrome bd oxygen reductase...
July 3, 2018: MBio
Christopher R Evans, Yongqiang Fan, Kalyn Weiss, Jiqiang Ling
Gene expression has been considered a highly accurate process, and deviation from such fidelity has been shown previously to be detrimental for the cell. More recently, increasing evidence has supported the notion that the accuracy of gene expression is indeed flexibly variable. The levels of errors during gene expression differ from condition to condition and even from cell to cell within genetically identical populations grown under the same conditions. The different levels of errors resulting from inaccurate gene expression are now known to play key roles in regulating microbial stress responses and host interactions...
July 3, 2018: MBio
Ling Zhu, Kangwei Xu, Nan Wang, Lei Cao, Junlan Wu, Qiang Gao, Elizabeth E Fry, David I Stuart, Zihe Rao, Junzhi Wang, Xiangxi Wang
Despite significant advances in health care, outbreaks of infections by enteroviruses (EVs) continue to plague the Asia-Pacific region every year. Enterovirus 71 (EV71) causes hand-foot-and-mouth disease (HFMD), for which there are currently no therapeutics. Here, we report two new antibodies, A9 and D6, that potently neutralize EV71. A9 exhibited a 50% neutralizing concentration (neut50 ) value of 0.1 nM against EV71, which was 10-fold lower than that observed for D6. Investigation into the mechanisms of neutralization revealed that binding of A9 to EV71 blocks receptor binding but also destabilizes and damages the virus capsid structure...
July 3, 2018: MBio
Yingbo Shen, Zuowei Wu, Yang Wang, Rong Zhang, Hong-Wei Zhou, Shaolin Wang, Lei Lei, Mei Li, Jiachang Cai, Jonathan Tyrrell, Guo-Bao Tian, Congming Wu, Qijing Zhang, Jianzhong Shen, Timothy R Walsh, Zhangqi Shen
The recent emergence of a transferable colistin resistance mechanism, MCR-1, has gained global attention because of its threat to clinical treatment of infections caused by multidrug-resistant Gram-negative bacteria. However, the possible transmission route of mcr-1 among Enterobacteriaceae species in clinical settings is largely unknown. Here, we present a comprehensive genomic analysis of Escherichia coli isolates collected in a hospital in Hangzhou, China. We found that mcr-1 -carrying isolates from clinical infections and feces of inpatients and healthy volunteers were genetically diverse and were not closely related phylogenetically, suggesting that clonal expansion is not involved in the spread of mcr-1 The mcr-1 gene was found on either chromosomes or plasmids, but in most of the E...
July 3, 2018: MBio
Abigail J Perrin, Christine R Collins, Matthew R G Russell, Lucy M Collinson, David A Baker, Michael J Blackman
Apicomplexa are obligate intracellular parasites that actively invade, replicate within, and egress from host cells. The parasite actinomyosin-based molecular motor complex (often referred to as the glideosome) is considered an important mediator of parasite motility and virulence. Mature intracellular parasites often become motile just prior to egress from their host cells, and in some genera, this motility is important for successful egress as well as for subsequent invasion of new host cells. To determine whether actinomyosin-based motility is important in the red blood cell egress and invasion activities of the malaria parasite, we have used a conditional genetic approach to delete GAP45 , a primary component of the glideosome, in asexual blood stages of Plasmodium falciparum Our results confirm the essential nature of GAP45 for invasion but show that P...
July 3, 2018: MBio
Sho Iketani, Ryan C Shean, Marion Ferren, Negar Makhsous, Dolly B Aquino, Amedee des Georges, Bert Rima, Cyrille Mathieu, Matteo Porotto, Anne Moscona, Alexander L Greninger
Human parainfluenza viruses cause a large burden of human respiratory illness. While much research relies upon viruses grown in cultured immortalized cells, human parainfluenza virus 3 (HPIV-3) evolves in culture. Cultured viruses differ in their properties compared to clinical strains. We present a genome-wide survey of HPIV-3 adaptations to culture using metagenomic next-generation sequencing of matched pairs of clinical samples and primary culture isolates (zero passage virus). Nonsynonymous changes arose during primary viral isolation, almost entirely in the genes encoding the two surface glycoproteins-the receptor binding protein hemagglutinin-neuraminidase (HN) or the fusion protein (F)...
July 3, 2018: MBio
Eric Baranowski, Emilie Dordet-Frisoni, Eveline Sagné, Marie-Claude Hygonenq, Gabriela Pretre, Stéphane Claverol, Laura Fernandez, Laurent Xavier Nouvel, Christine Citti
The discovery of integrative conjugative elements (ICEs) in wall-less mycoplasmas and the demonstration of their role in massive gene flows within and across species have shed new light on the evolution of these minimal bacteria. Of these, the ICE of the ruminant pathogen Mycoplasma agalactiae (ICEA) represents a prototype and belongs to a new clade of the Mutator-like superfamily that has no preferential insertion site and often occurs as multiple chromosomal copies. Here, functional genomics and mating experiments were combined to address ICEA functions and define the minimal ICEA chassis conferring conjugative properties to M...
July 3, 2018: MBio
Yugen Zhang, Dirk P Dittmer, Piotr A Mieczkowski, Kurtis M Host, William G Fusco, Joseph A Duncan, Blossom Damania
Retinoic acid-inducible gene I (RIG-I) is a cytosolic pathogen recognition receptor that initiates the innate immune response against many RNA viruses. We previously showed that RIG-I restricts Kaposi's sarcoma-associated herpesvirus (KSHV) reactivation (J. A. West et al., J Virol 88:5778-5787, 2014, In this study, we report that KSHV stimulates the RIG-I signaling pathway in a RNA polymerase (Pol) III-independent manner and subsequently induces type I interferon (IFN) responses...
July 3, 2018: MBio
Breah LaSarre, David T Kysela, Barry D Stein, Adrien Ducret, Yves V Brun, James B McKinlay
In bacteria and eukaryotes alike, proper cellular physiology relies on robust subcellular organization. For the phototrophic purple nonsulfur bacteria (PNSB), this organization entails the use of a light-harvesting, membrane-bound compartment known as the intracytoplasmic membrane (ICM). Here we show that ICMs are spatially and temporally localized in diverse patterns among PNSB. We visualized ICMs in live cells of 14 PNSB species across nine genera by exploiting the natural autofluorescence of the photosynthetic pigment bacteriochlorophyll (BChl)...
July 3, 2018: MBio
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