A genetic screen in rodent malaria parasites identifies five new apicoplast putative membrane transporters, one of which is essential in human malaria parasites
Summary
The malaria‐causing parasite, Plasmodium, contains a unique non‐photosynthetic plastid known as the apicoplast. The apicoplast is an essential organelle bound by four membranes. Although membrane transporters are attractive drug targets, only two transporters have been characterised in the malaria parasite apicoplast membranes. We selected 27 candidate apicoplast membrane proteins, 20 of which are annotated as putative membrane transporters, and performed a genetic screen in P. berghei to determine blood stage essentiality and subcellular localisation. Eight apparently essential blood stage genes were identifie...
Source: Cellular Microbiology - September 13, 2017 Category: Microbiology Authors: Claire P. Sayers, Vanessa Mollard, Hayley D. Buchanan, Geoffrey I. McFadden, Christopher D. Goodman Tags: RESEARCH ARTICLE Source Type: research
Bcl10 synergistically links CEACAM3 and TLR ‐dependent inflammatory signalling
Summary
The neutrophil‐specific innate immune receptor CEACAM3 functions as a decoy to capture Gram‐negative pathogens, such as Neisseria gonorrhoeae, that exploit CEACAM family members to adhere to the epithelium. Bacterial binding to CEACAM3 results in their efficient engulfment and triggers activation of an NF‐κB‐dependent inflammatory response by human neutrophils. Herein, we report that CEACAM3 cross‐linking is not sufficient for induction of cytokine production, and show that the inflammatory response induced by N. gonorrhoeae infection is elicited by an integration of signals from CEACAM3 and Toll‐like ...
Source: Cellular Microbiology - September 9, 2017 Category: Microbiology Authors: Anna Sintsova, Cynthia X. Guo, Helen Sarantis, Tak W. Mak, Michael Glogauer, Scott D. Gray ‐Owen Tags: RESEARCH ARTICLE Source Type: research
N ‐(3‐oxo‐acyl)‐homoserine lactone induces apoptosis primarily through a mitochondrial pathway in fibroblasts
ABSTRACT
N‐(3‐oxododecanoyl)‐homoserine lactone (C12) is produced by Pseudomonas aeruginosa to function as a quorum‐sensing molecule for bacteria‐bacteria communication. C12 is also known to influence many aspects of human host cell physiology, including induction of cell death. However, the signaling pathway(s) leading to C12‐triggered cell death is (are) still not completely known. To clarify cell death signaling induced by C12, we examined mouse embryonic fibroblasts (MEFs) deficient in “initiator” caspases or “effector” caspases. Our data indicate that C12 selectively induces the mitochondria‐depe...
Source: Cellular Microbiology - September 6, 2017 Category: Microbiology Authors: Aaron M. Neely, Guoping Zhao, Christian Schwarzer, Nicole S. Stivers, Aaron G. Whitt, Shuhan Meng, Joseph A. Burlison, Terry E. Machen, Chi Li Tags: RESEARCH ARTICLE Source Type: research
Issue Information
No abstract is available for this article. (Source: Cellular Microbiology)
Source: Cellular Microbiology - September 6, 2017 Category: Microbiology Tags: ISSUE INFORMATION Source Type: research
Caveolin 1 restricts Group A Streptococcus invasion of nonphagocytic host cells
Abstract
Caveolae are composed of 2 major proteins, caveolin 1 (CAV1) and cavin 1 or polymerase transcript release factor I (CAVIN1). Here, we demonstrate that CAV1 levels modulate invasion of Group A Streptococcus (GAS) into nonphagocytic mammalian cells. GAS showed enhanced internalisation into CAV1‐knockout mouse embryonic fibroblasts and CAV1 knockdown human epithelial HEp‐2 cells, whereas overexpression of CAV1 in HEp‐2 cells reduced GAS invasion. This effect was not dependent on the expression of the GAS fibronectin binding protein SfbI, which had previously been implicated in caveolae‐mediated uptake. Nor wa...
Source: Cellular Microbiology - September 6, 2017 Category: Microbiology Authors: Jin Yan Lim, Timothy C. Barnett, Michele Bastiani, Kerrie ‐Ann McMahon, Charles Ferguson, Richard I. Webb, Robert G. Parton, Mark J. Walker Tags: RESEARCH ARTICLE Source Type: research
A novel in vitro model for hematogenous spreading of S. aureus device biofilms demonstrating clumping dispersal as an advantageous dissemination mechanism
Summary
Staphylococcus aureus is able to disseminate from vascular device biofilms to the blood and organs, resulting in life‐threatening infections such as endocarditis. The mechanisms behind spreading are largely unknown, especially how the bacterium escapes immune effectors and antibiotics in the process. Using an in vitro catheter infection model, we studied S. aureus biofilm growth, late‐stage dispersal, and reattachment to downstream endothelial cell layers. The ability of the released biofilm material to resist host response and disseminate in vivo was furthermore studied in whole blood‐ and phagocyte survival...
Source: Cellular Microbiology - September 5, 2017 Category: Microbiology Authors: R.B. Gr ønnemose, K.L. Saederup, H.J. Kolmos, S.W.K. Hansen, C.A. Asferg, K.J. Rasmussen, Y. Palarasah, T.E. Andersen Tags: RESEARCH ARTICLE Source Type: research
Borrelia burgdorferi outer surface protein C (OspC) binds complement component C4b and confers bloodstream survival.
Abstract
Borrelia burgdorferi (Bb) is the causative agent of Lyme disease in the US, a disease that can result in carditis, and chronic and debilitating arthritis and/or neurologic symptoms if left untreated. Bb survives in the midgut of the Ixodes scapularis tick, or within tissues of immunocompetent hosts. In the early stages of infection, the bacteria are present in the bloodstream where they must resist clearance by the innate immune system of the host. We have found a novel role for OspC from B. burgdorferi and B. garinii in interactions with the complement component C4b and bloodstream survival in vivo. Our data show...
Source: Cellular Microbiology - September 1, 2017 Category: Microbiology Authors: Jennifer A. Caine, Yi ‐Pin Lin, Julie R. Kessler, Hiromi Sato, John M. Leong, Jenifer Coburn Tags: RESEARCH ARTICLE Source Type: research
A role for host cell exocytosis in InlB ‐mediated internalisation of Listeria monocytogenes
Summary
The bacterial surface protein InlB mediates internalisation of Listeria monocytogenes into human cells through interaction with the host receptor tyrosine kinase, Met. InlB‐mediated entry requires localised polymerisation of the host actin cytoskeleton. Apart from actin polymerisation, roles for other host processes in Listeria entry are unknown. Here, we demonstrate that exocytosis in the human cell promotes InlB‐dependent internalisation. Using a probe consisting of VAMP3 with an exofacial green fluorescent protein tag, focal exocytosis was detected during InlB‐mediated entry. Exocytosis was dependent on Me...
Source: Cellular Microbiology - August 25, 2017 Category: Microbiology Authors: Hoan Van Ngo, Manmeet Bhalla, Da ‐Yuan Chen, Keith Ireton Tags: RESEARCH ARTICLE Source Type: research
Aspergillus fumigatus protein phosphatase PpzA is involved in iron assimilation, secondary metabolite production, and virulence
Summary
Metal restriction imposed by mammalian hosts during an infection is a common mechanism of defence to reduce or avoid the pathogen infection. Metals are essential for organism survival due to its involvement in several biological processes. Aspergillus fumigatus causes invasive aspergillosis, a disease that typically manifests in immunocompromised patients. A. fumigatus PpzA, the catalytic subunit of protein phosphatase Z (PPZ), has been recently identified as associated with iron assimilation. A. fumigatus has 2 high‐affinity mechanisms of iron acquisition during infection: reductive iron assimilation and sider...
Source: Cellular Microbiology - August 17, 2017 Category: Microbiology Authors: Adriana Oliveira Manfiolli, Patr ícia Alves Castro, Thaila Fernanda Reis, Stephen Dolan, Sean Doyle, Gary Jones, Diego M. Riaño Pachón, Mevlüt Ulaş, Luke M. Noble, Derek J. Mattern, Axel A. Brakhage, Vito Valiante, Rafael Silva‐Rocha, Ozgur Bayram, Tags: RESEARCH ARTICLE Source Type: research
Caveolin ‐1 restricts group A Streptococcus invasion of non‐phagocytic host cells
Summary
Caveolae are composed of two major proteins, caveolin‐1 (CAV1) and cavin‐1/polymerase transcript factor I (CAVIN1). Here we demonstrate that CAV1 levels modulate invasion of group A Streptococcus (GAS) into non‐phagocytic mammalian cells. GAS showed enhanced internalization into CAV1 knockout mouse embryonic fibroblasts (MEFs), and CAV1 knockdown human epithelial HEp‐2 cells, whereas over‐expression of CAV1 in HEp‐2 cells reduced GAS invasion. This effect was not dependent on the expression of the GAS fibronectin binding protein SfbI, which had previously been implicated in caveolae‐mediated uptake. N...
Source: Cellular Microbiology - August 4, 2017 Category: Microbiology Authors: Jin Yan Lim, Timothy C. Barnett, Michele Bastiani, Kerrie ‐Ann McMahon, Charles Ferguson, Richard I. Webb, Robert G. Parton, Mark J. Walker Tags: RESEARCH ARTICLE Source Type: research
Issue Information
No abstract is available for this article. (Source: Cellular Microbiology)
Source: Cellular Microbiology - August 4, 2017 Category: Microbiology Tags: ISSUE INFORMATION Source Type: research
Helicobacter pylori Outer Inflammatory Protein A (OipA) suppresses apoptosis of AGS gastric cells in vitro
This study aims to elucidate the role of OipA in H. pylori infection using clinical strains harboring oipA “on” and “off” motifs. Proteomics analysis was performed on AGS cell pre and post‐infection with H. pylori oipA “on” and “off” strains, using liquid chromatography / mass spectrometry. AGS apoptosis and cell cycle assays were performed. Moreover, expression of vacuolating cytotoxin A (VacA) was screened using Western blotting. AGS proteins that have been suggested previously to play a role or associated with gastric disease were down‐regulated post‐infection with oipA “off” strains comparing ...
Source: Cellular Microbiology - August 1, 2017 Category: Microbiology Authors: Anis Rageh Al ‐Maleki, Mun Fai Loke, Sook Yin Lui, Nur Siti Khadijah Ramli, Yalda Khosravi, Chow Goon Ng, Gopinath Venkatraman, Khean‐Lee Goh, Bow Ho, Jamuna Vadivelu Tags: RESEARCH ARTICLE Source Type: research
Aspergillus fumigatus protein phosphatase PpzA is involved in iron assimilation, secondary metabolite production, and virulence
Abstract
Metal restriction imposed by mammalian hosts during an infection is a common mechanism of defense to reduce or avoid the pathogen infection. Metals are essential for organism survival due to its involvement in several biological processes. Aspergillus fumigatus causes invasive aspergillosis (IA), a disease that typically manifests in immunocompromised patients. A. fumigatus PpzA, the catalytic subunit of protein phosphatase Z (PPZ), has been recently identified as associated with iron assimilation. A. fumigatus has two high affinity mechanisms of iron acquisition during infection: reductive iron assimilation (RIA)...
Source: Cellular Microbiology - July 28, 2017 Category: Microbiology Authors: Adriana Oliveira Manfiolli, Patr ícia Alves Castro, Thaila Fernanda Reis, Stephen Dolan, Sean Doyle, Gary Jones, Diego M. Riaño Pachón, Mevlüt ulaş, Luke M. Noble, Derek J. Mattern, Axel A. Brakhage, Vito Valiante, Rafael Silva‐Rocha, Ozgur Bayram, Tags: RESEARCH ARTICLE Source Type: research
Subversion of innate immune responses by Francisella involves the disruption of TRAF3 and TRAF6 signaling complexes
Summary
The success of pathogens depends on their ability to circumvent immune defenses. Francisella tularensis is one of the most infectious bacteria known. The remarkable virulence of Francisella is believed to be due to its capacity to evade or subvert the immune system, but how remains obscure. Here we show that Francisella triggers but concomitantly inhibits the Toll‐like receptor (TLR), RIG‐I‐like receptor (RLR) and Cytoplasmic DNA (CDR) pathways. Francisella subverts these pathways at least in part by inhibiting K63‐linked polyubiquitination and assembly of TRAF6 and TRAF3 complexes that control the transcri...
Source: Cellular Microbiology - July 26, 2017 Category: Microbiology Authors: Daniela Putzova, Swarupa Panda, Anetta H ärtlova, Jiří Stulík, Nelson O. Gekara Tags: RESEARCH ARTICLE Source Type: research
Distinct roles of the 7 ‐transmembrane receptor protein Rta3 in regulating the asymmetric distribution of phosphatidylcholine across the plasma membrane and biofilm formation in Candida albicans
Abstract
Fungal pathogens like Candida albicans exhibit several survival mechanisms to evade attack by antifungals and colonize host tissues. Rta3, a member of the Rta1‐like family of lipid‐translocating exporters has a 7‐transmembrane domain (7TMD) topology, similar to the G‐protein‐coupled receptors (GPCR) and is unique to the fungal kingdom. Our findings point towards a role for the plasma membrane localized Rta3 in providing tolerance to miltefosine, an analog of alkylphosphocholine, by maintaining mitochondrial energetics. Concurrent with miltefosine susceptibility, the rta3Δ/Δ strain displays increased in...
Source: Cellular Microbiology - July 26, 2017 Category: Microbiology Authors: Archita Srivastava, Shabnam Sircaik, Farha Husain, Edwina Thomas, Shivani Ror, Sumit Rastogi, Darakshan Alim, Priyanka Bapat, David R. Andes, Clarissa J. Nobile, Sneh L. Panwar Tags: RESEARCH ARTICLE Source Type: research
