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Cell Host & Microbe

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https://www.readbyqxmd.com/read/28041930/a-single-legionella-effector-catalyzes-a-multistep-ubiquitination-pathway-to-rearrange-tubular-endoplasmic-reticulum-for-replication
#1
Kristin M Kotewicz, Vinay Ramabhadran, Nicole Sjoblom, Joseph P Vogel, Eva Haenssler, Mengyun Zhang, Jessica Behringer, Rebecca A Scheck, Ralph R Isberg
Intracellular pathogens manipulate host organelles to support replication within cells. For Legionella pneumophila, the bacterium translocates proteins that establish an endoplasmic reticulum (ER)-associated replication compartment. We show here that the bacterial Sde proteins target host reticulon 4 (Rtn4) to control tubular ER dynamics, resulting in tubule rearrangements as well as alterations in Rtn4 associated with the replication compartment. These rearrangements are triggered via Sde-promoted ubiquitin transfer to Rtn4, occurring almost immediately after bacterial uptake...
December 22, 2016: Cell Host & Microbe
https://www.readbyqxmd.com/read/28081446/host-to-host-transmission-of-streptococcus-pneumoniae-is-driven-by-its-inflammatory-toxin-pneumolysin
#2
M Ammar Zafar, Yang Wang, Shigeto Hamaguchi, Jeffrey N Weiser
Host-to-host transmission is a critical step for infection. Here we studied transmission of the opportunistic pathogen Streptococcus pneumoniae in an infant mouse model. Transmission from nasally colonized pups required high levels of bacterial shedding in nasal secretions and was temporally correlated with, and dependent upon, the acute inflammatory response. Pneumolysin, a pore-forming cytotoxin and major virulence determinant, was both necessary and sufficient to promote inflammation, which increased shedding and allowed for intralitter transmission...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28081445/bringing-the-dynamic-microbiome-to-life-with-animations
#3
Yoshiki Vázquez-Baeza, Antonio Gonzalez, Larry Smarr, Daniel McDonald, James T Morton, Jose A Navas-Molina, Rob Knight
Our bodies and natural environment contain complex microbial communities, colloquially termed microbiomes. We previously created a web-based application, EMPeror, for visualizing ordinations derived from comparisons of these microbiome communities. We have now improved EMPeror to create interactive animations that connect successive samples to highlight patterns over time.
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28081444/host-to-host-transmission-of-the-pneumococcus-new-victims-of-a-toxic-relationship
#4
Claudia Trappetti, James C Paton
Host-to-host transmission is critical for survival of the human-adapted bacterium Streptococcus pneumoniae. In this issue of Cell Host & Microbe, Zafar et al. (2017) show that transmission is dependent on nasopharyngeal inflammation elicited by the toxin pneumolysin, causing increased shedding and enhanced survival of the bacterium in the environment.
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28081443/the-bacterial-t6ss-effector-evpp-prevents-nlrp3-inflammasome-activation-by-inhibiting-the-ca-2-dependent-mapk-jnk-pathway
#5
Hao Chen, Dahai Yang, Fajun Han, Jinchao Tan, Lingzhi Zhang, Jingfan Xiao, Yuanxing Zhang, Qin Liu
Inflammasome activation is an important innate immune defense mechanism against bacterial infection, and in return, bacteria express virulence determinants that counteract inflammasome activation. Many such effectors are secreted into host cells via specialized bacterial secretion systems. Here, the intracellular pathogenic bacterium Edwardsiella tarda was demonstrated to activate NLRC4 and NLRP3 inflammasomes via a type III secretion system (T3SS), and to inhibit NLRP3 inflammasome via a type VI secretion system (T6SS), indicating the antagonistic roles of these systems in inflammasome signaling...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28081442/mapping-and-role-of-the-cd8-t-cell-response-during-primary-zika-virus-infection-in-mice
#6
Annie Elong Ngono, Edward A Vizcarra, William W Tang, Nicholas Sheets, Yunichel Joo, Kenneth Kim, Matthew J Gorman, Michael S Diamond, Sujan Shresta
CD8(+) T cells may play a dual role in protection against and pathogenesis of flaviviruses, including Zika virus (ZIKV). We evaluated the CD8(+) T cell response in ZIKV-infected LysMCre(+)IFNAR(fl/fl) C57BL/6 (H-2(b)) mice lacking the type I interferon receptor in a subset of myeloid cells. In total, 26 and 15 CD8(+) T cell-reactive peptides for ZIKV African (MR766) and Asian (FSS13025) lineage strains, respectively, were identified and validated. CD8(+) T cells from infected mice were polyfunctional and mediated cytotoxicity...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28081441/warfare-between-host-immunity-and-bacterial-weapons
#7
Manda Yu, Erh-Min Lai
Bacterial pathogens deploy protein secretion systems to facilitate infection and colonization of their hosts. In this issue of Cell Host & Microbe, Chen et al. (2017) report a new role for a type VI secretion effector in promoting bacterial colonization by preventing inflammasome activation induced by a type III secretion system.
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28081440/a-knockout-screen-of-apiap2-genes-reveals-networks-of-interacting-transcriptional-regulators-controlling-the-plasmodium-life-cycle
#8
Katarzyna Modrzynska, Claudia Pfander, Lia Chappell, Lu Yu, Catherine Suarez, Kirsten Dundas, Ana Rita Gomes, David Goulding, Julian C Rayner, Jyoti Choudhary, Oliver Billker
A family of apicomplexa-specific proteins containing AP2 DNA-binding domains (ApiAP2s) was identified in malaria parasites. This family includes sequence-specific transcription factors that are key regulators of development. However, functions for the majority of ApiAP2 genes remain unknown. Here, a systematic knockout screen in Plasmodium berghei identified ten ApiAP2 genes that were essential for mosquito transmission: four were critical for the formation of infectious ookinetes, and three were required for sporogony...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28081439/knotty-zika-virus-blocks-exonuclease-to-produce-subgenomic-flaviviral-rnas
#9
Nandan S Gokhale, Stacy M Horner
In a recent issue of Science, Akiyama et al. (2016) prove the existence of a pseudoknot that stabilizes a nuclease-resistant RNA structure in the 3' untranslated region of Zika virus. This reinforced structure blocks the 5'→3' exonuclease Xrn1 for the production of pathogenic subgenomic flaviviral RNAs.
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28041931/prior-dietary-practices-and-connections-to-a-human-gut-microbial-metacommunity-alter-responses-to-diet-interventions
#10
Nicholas W Griffin, Philip P Ahern, Jiye Cheng, Andrew C Heath, Olga Ilkayeva, Christopher B Newgard, Luigi Fontana, Jeffrey I Gordon
Ensuring that gut microbiota respond consistently to prescribed dietary interventions, irrespective of prior dietary practices (DPs), is critical for effective nutritional therapy. To address this, we identified DP-associated gut bacterial taxa in individuals either practicing chronic calorie restriction with adequate nutrition (CRON) or without dietary restrictions (AMER). When transplanted into gnotobiotic mice, AMER and CRON microbiota responded predictably to CRON and AMER diets but with variable response strengths...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28041929/the-chlamydia-trachomatis-inclusion-membrane-protein-cpos-counteracts-sting-mediated-cellular-surveillance-and-suicide-programs
#11
Barbara S Sixt, Robert J Bastidas, Ryan Finethy, Ryan M Baxter, Victoria K Carpenter, Guido Kroemer, Jörn Coers, Raphael H Valdivia
Evading cell death is critical for Chlamydia to maintain a replicative niche, but the underlying mechanisms are unknown. We screened a library of Chlamydia mutants for modulators of cell death. Inactivation of the inclusion membrane protein CpoS (Chlamydia promoter of survival) induced rapid apoptotic and necrotic death in infected cells. The protection afforded by CpoS is limited to the inclusion in which it resides, indicating that it counteracts a spatially restricted pro-death signal. CpoS-deficient Chlamydia induced an exacerbated type I interferon response that required the host cGAS/STING/TBK1/IRF3 signaling pathway...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28041928/positive-gene-regulation-by-a-natural-protective-mirna-enables-arbuscular-mycorrhizal-symbiosis
#12
Jean-Malo Couzigou, Dominique Lauressergues, Olivier André, Caroline Gutjahr, Bruno Guillotin, Guillaume Bécard, Jean-Philippe Combier
Arbuscular mycorrhizal (AM) symbiosis associates most plants with fungi of the phylum Glomeromycota. The fungus penetrates into roots and forms within cortical cell branched structures called arbuscules for nutrient exchange. We discovered that miR171b has a mismatched cleavage site and is unable to downregulate the miR171 family target gene, LOM1 (LOST MERISTEMS 1). This mismatched cleavage site is conserved among plants that establish AM symbiosis, but not in non-mycotrophic plants. Unlike other members of the miR171 family, miR171b stimulates AM symbiosis and is expressed specifically in root cells that contain arbuscules...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28017661/recent-h3n2-viruses-have-evolved-specificity-for-extended-branched-human-type-receptors-conferring-potential-for-increased-avidity
#13
Wenjie Peng, Robert P de Vries, Oliver C Grant, Andrew J Thompson, Ryan McBride, Buyankhishig Tsogtbaatar, Peter S Lee, Nahid Razi, Ian A Wilson, Robert J Woods, James C Paulson
Human and avian influenza viruses recognize different sialic acid-containing receptors, referred to as human-type (NeuAcα2-6Gal) and avian-type (NeuAcα2-3Gal), respectively. This presents a species barrier for aerosol droplet transmission of avian viruses in humans and ferrets. Recent reports have suggested that current human H3N2 viruses no longer have strict specificity toward human-type receptors. Using an influenza receptor glycan microarray with extended airway glycans, we find that H3N2 viruses have in fact maintained human-type specificity, but they have evolved preference for a subset of receptors comprising branched glycans with extended poly-N-acetyl-lactosamine (poly-LacNAc) chains, a specificity shared with the 2009 pandemic H1N1 (Cal/04) hemagglutinin...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28017660/prevotella-as-a-hub-for-vaginal-microbiota-under-the-influence-of-host-genetics-and-their-association-with-obesity
#14
Jiyeon Si, Hyun Ju You, Junsun Yu, Joohon Sung, GwangPyo Ko
While the vaginal ecosystem is maintained through mutualistic relationships between the host and the vaginal bacteria, the effect of host genetics on the vaginal microbiota has not been well characterized. We examined the heritability of vaginal microbiota and its association with obesity in 542 Korean females, including 222 monozygotic and 56 dizygotic twins. The vaginal microbiota significantly varied depending on host menopausal status and bacterial vaginosis. Lactobacillus and Prevotella, whose relative abundances are strongly associated with bacterial vaginosis, were the most heritable bacteria among the beneficial and potentially pathogenic vaginal microbiota, respectively...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28017659/the-ubiquitin-ligase-smurf1-functions-in-selective-autophagy-of-mycobacterium-tuberculosis-and-anti-tuberculous-host-defense
#15
Luis H Franco, Vidhya R Nair, Caitlyn R Scharn, Ramnik J Xavier, Jose R Torrealba, Michael U Shiloh, Beth Levine
During antibacterial autophagy, ubiquitination of intracellular bacteria recruits proteins that mediate bacterial delivery to the lysosome for degradation. Smurf1 is an E3 ubiquitin ligase whose role in selective bacterial autophagy is unknown. We show that Smurf1 facilitates selective autophagy of the human pathogen Mycobacterium tuberculosis (Mtb). Smurf1(-/-) macrophages are defective in recruiting polyubiquitin, the proteasome, the ubiquitin-binding autophagy adaptor NBR1, the autophagy protein LC3, and the lysosomal marker LAMP1 to Mtb-associated structures and are more permissive for Mtb growth...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/27978436/the-mtor-complex-controls-hiv-latency
#16
Emilie Besnard, Shweta Hakre, Martin Kampmann, Hyung W Lim, Nina N Hosmane, Alyssa Martin, Michael C Bassik, Erik Verschueren, Emilie Battivelli, Jonathan Chan, J Peter Svensson, Andrea Gramatica, Ryan J Conrad, Melanie Ott, Warner C Greene, Nevan J Krogan, Robert F Siliciano, Jonathan S Weissman, Eric Verdin
A population of CD4 T lymphocytes harboring latent HIV genomes can persist in patients on antiretroviral therapy, posing a barrier to HIV eradication. To examine cellular complexes controlling HIV latency, we conducted a genome-wide screen with a pooled ultracomplex shRNA library and in vitro system modeling HIV latency and identified the mTOR complex as a modulator of HIV latency. Knockdown of mTOR complex subunits or pharmacological inhibition of mTOR activity suppresses reversal of latency in various HIV-1 latency models and HIV-infected patient cells...
December 14, 2016: Cell Host & Microbe
https://www.readbyqxmd.com/read/27978435/an-e3%C3%A2-ubiquitin-ligase-bag-protein-module-controls-plant-innate-immunity-and-broad-spectrum-disease-resistance
#17
Quanyuan You, Keran Zhai, Donglei Yang, Weibing Yang, Jingni Wu, Junzhong Liu, Wenbo Pan, Jianjun Wang, Xudong Zhu, Yikun Jian, Jiyun Liu, Yingying Zhang, Yiwen Deng, Qun Li, Yonggen Lou, Qi Xie, Zuhua He
Programmed cell death (PCD) and immunity in plants are tightly controlled to promote antimicrobial defense while preventing autoimmunity. However, the mechanisms contributing to this immune homeostasis are poorly understood. Here, we isolated a rice mutant ebr1 (enhanced blight and blast resistance 1) that shows enhanced broad-spectrum bacterial and fungal disease resistance, but displays spontaneous PCD, autoimmunity, and stunted growth. EBR1 encodes an E3 ubiquitin ligase that interacts with OsBAG4, which belongs to the BAG (Bcl-2-associated athanogene) family that functions in cell death, growth arrest, and immune responses in mammals...
December 14, 2016: Cell Host & Microbe
https://www.readbyqxmd.com/read/27978434/an-apicomplexan-actin-binding-protein-serves-as-a-connector-and-lipid-sensor-to-coordinate-motility-and-invasion
#18
Damien Jacot, Nicolò Tosetti, Isa Pires, Jessica Stock, Arnault Graindorge, Yu-Fu Hung, Huijong Han, Rita Tewari, Inari Kursula, Dominique Soldati-Favre
Apicomplexa exhibit a unique form of substrate-dependent gliding motility central for host cell invasion and parasite dissemination. Gliding is powered by rearward translocation of apically secreted transmembrane adhesins via their interaction with the parasite actomyosin system. We report a conserved armadillo and pleckstrin homology (PH) domain-containing protein, termed glideosome-associated connector (GAC), that mediates apicomplexan gliding motility, invasion, and egress by connecting the micronemal adhesins with the actomyosin system...
December 14, 2016: Cell Host & Microbe
https://www.readbyqxmd.com/read/27978433/exploiting-old-pathogens-to-create-new-therapeutics
#19
Tiffany Bouchery, Nicola L Harris
Intestinal worms are well known for their potent immuno-modulatory capacity. In a recent study, Navarro et al. (2016) identify a secreted hookworm protein that can suppress allergic responses in both mice and humans. This represents an exciting strategy for treating chronic inflammatory disorders such as allergy.
December 14, 2016: Cell Host & Microbe
https://www.readbyqxmd.com/read/27978432/retrovirus-integration-some-assembly-required
#20
Ibraheem Ali, Ryan J Conrad, Melanie Ott
Integration is a key feature of the retroviral life cycle. This process involves packaging of the viral genome into chromatin, which is often assumed to occur as a post-integration step. In this issue of Cell Host & Microbe, Wang and colleagues (Wang et al., 2016) show that chromatinization occurs before integration, raising new questions about the role of histones in retroviral integration and transcription.
December 14, 2016: Cell Host & Microbe
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