المؤلفون: Colleen M. Pike, Matthew H. Foley, Stephanie A. Montgomery, Casey M. Theriot, Alissa J. Rivera, Ruth J. Parsons, Michael R. McLaren, Joshua R. Fletcher

المصدر: Nature Communications, Vol 12, Iss 1, Pp 1-14 (2021)
Nature Communications

مصطلحات موضوعية: Male, 0301 basic medicine, Antibiotics, General Physics and Astronomy, Gut flora, medicine.disease_cause, Mice, Sigma factor, Bacteroides, RNA-Seq, Intestinal Mucosa, Pathogen, Regulation of gene expression, Multidisciplinary, Anti-Bacterial Agents, Extracellular Matrix, RNA, Bacterial, Host-Pathogen Interactions, Female, Pathogens, medicine.symptom, medicine.drug_class, Science, Bacterial Toxins, 030106 microbiology, Sigma Factor, Inflammation, Colonisation resistance, Biology, digestive system, Article, General Biochemistry, Genetics and Molecular Biology, Bacterial genetics, Microbiology, 03 medical and health sciences, Bacterial Proteins, medicine, Animals, Humans, Colonic diseases, Toxin, Clostridioides difficile, Gene Expression Regulation, Bacterial, Nutrients, General Chemistry, Pseudomembranous colitis, biology.organism_classification, Matrix Metalloproteinases, Gastrointestinal Microbiome, Disease Models, Animal, 030104 developmental biology, Proteolysis, Clostridium Infections, Microbiome, Transcriptome

الوصف: Clostridioides difficile is a bacterial pathogen that causes a range of clinical disease from mild to moderate diarrhea, pseudomembranous colitis, and toxic megacolon. Typically, C. difficile infections (CDIs) occur after antibiotic treatment, which alters the gut microbiota, decreasing colonization resistance against C. difficile. Disease is mediated by two large toxins and the expression of their genes is induced upon nutrient depletion via the alternative sigma factor TcdR. Here, we use tcdR mutants in two strains of C. difficile and omics to investigate how toxin-induced inflammation alters C. difficile metabolism, tissue gene expression and the gut microbiota, and to determine how inflammation by the host may be beneficial to C. difficile. We show that C. difficile metabolism is significantly different in the face of inflammation, with changes in many carbohydrate and amino acid uptake and utilization pathways. Host gene expression signatures suggest that degradation of collagen and other components of the extracellular matrix by matrix metalloproteinases is a major source of peptides and amino acids that supports C. difficile growth in vivo. Lastly, the inflammation induced by C. difficile toxin activity alters the gut microbiota, excluding members from the genus Bacteroides that are able to utilize the same essential nutrients released from collagen degradation.
The effects of antibiotics on the gut microbiota can lead to enhanced colonization of Clostridioides difficile (C. difficile) and toxin-mediated pathogenesis. Here, using defined toxin-mutant strains and a murine model, the authors provide insights into how toxin-induced inflammation alters C. difficile metabolism, host tissue gene expression and gut microbiota, together influencing a beneficial niche for infection.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::27f1dced314a70d0ed372007695ffe64Test
https://doaj.org/article/9e6aa7aed98f489781f33be6a4d04611Test

المؤلفون: Colleen M. Pike, Casey M. Theriot

المصدر: J Infect Dis

مصطلحات موضوعية: 0301 basic medicine, medicine.drug_class, 030106 microbiology, Antibiotics, Supplement Articles, Colonisation resistance, Biology, Clostridium difficile, Antimicrobial, biology.organism_classification, Microbiology, 03 medical and health sciences, 030104 developmental biology, Infectious Diseases, Bacteriocin, medicine, Immunology and Allergy, Microbiome, Bacteria, Clostridioides

الوصف: Clostridioides difficile is an urgent antimicrobial-resistant bacterium, causing mild to moderate and sometimes life-threatening disease. Commensal gut microbes are critical for providing colonization resistance against C difficile and can be leveraged as non-antibiotic alternative therapeutics for the prevention and treatment of C difficile infection.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3ef64ff2a487e1fdc5798a08208ffaa9Test
https://doi.org/10.1093/infdis/jiaa408Test

المؤلفون: Rebecca R. Noll, Stephanie S. Lehman, M. Ramona Neunuebel, Colleen M. Pike, Chad D. Williamson

مصطلحات موضوعية: Ubiquitin, biology, Effector, Autophagy, biology.protein, Cellular homeostasis, Secretion, biology.organism_classification, Pathogen, Legionella pneumophila, Intracellular, Cell biology

الوصف: Autophagy is a fundamental eukaryotic process that mediates clearance of unwanted molecules and facilitates nutrient release. The bacterial pathogen Legionella pneumophila establishes an intracellular niche within phagocytes by manipulating host cellular processes, such as autophagy. Effector proteins translocated by L. pneumophila’s Dot/Icm type IV secretion system have been shown to suppress autophagy. However evidence suggests that overall inhibition of autophagy may be detrimental to the bacterium. As autophagy contributes to cellular homeostasis and nutrient acquisition, L. pneumophila may translocate effectors that promote autophagy for these benefits. Here, we show that effector protein Lpg2411 binds phosphatidylinositol-3-phosphate lipids and preferentially binds autophagosomes. Translocated Lpg2411 accumulates late during infection and co-localizes with the autophagy receptor p62 and ubiquitin. Furthermore, autophagy is inhibited to a greater extent in host cells infected with a mutant strain lacking Lpg2411 compared to those infected with wild-type L. pneumophila, indicating that Lpg2411 stimulates autophagy to support the bacterium’s intracellular lifestyle.SummaryLegionella pneumophila translocates several effector proteins that inhibit autophagic processes. In this study, we find that the effector protein Lpg2411 targets autophagosomes during late stages of infection and promotes autophagy.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::c8cb3861ebab4bfd7b7c6098c54907d5Test
https://doi.org/10.1101/2021.07.08.451723Test

المؤلفون: Rebecca Boyer-Andersen, Lisa N. Kinch, Colleen M. Pike, M. Ramona Neunuebel, Jeffrey L. Caplan

المصدر: Journal of Biological Chemistry. 294:6405-6415

مصطلحات موضوعية: 0301 basic medicine, Endosome, Endosomes, Vacuole, Microbiology, Biochemistry, Legionella pneumophila, Phosphatidylinositol 3-Kinases, 03 medical and health sciences, chemistry.chemical_compound, Bacterial Proteins, Phosphatidylinositol Phosphates, Lysosome, medicine, Humans, Molecular Biology, Late endosome, Cellular localization, rab5 GTP-Binding Proteins, 030102 biochemistry & molecular biology, biology, Chemistry, Effector, Macrophages, Phosphatidylinositol 3-phosphate, Lysosome-Associated Membrane Glycoproteins, U937 Cells, Cell Biology, biology.organism_classification, Cell biology, HEK293 Cells, 030104 developmental biology, medicine.anatomical_structure, Vacuoles, Legionnaires' Disease, Lysosomes, Wortmannin, HeLa Cells

الوصف: Upon phagocytosis into macrophages, the intracellular bacterial pathogen Legionella pneumophila secretes effector proteins that manipulate host cell components, enabling it to evade lysosomal degradation. However, the bacterial proteins involved in this evasion are incompletely characterized. Here we show that the L. pneumophila effector protein RavD targets host membrane compartments and contributes to the molecular mechanism the pathogen uses to prevent encounters with lysosomes. Protein–lipid binding assays revealed that RavD selectively binds phosphatidylinositol-3-phosphate (PI(3)P) in vitro. We further determined that a C-terminal RavD region mediates the interaction with PI(3)P and that this interaction requires Arg-292. In transiently transfected mammalian cells, mCherry-RavD colocalized with the early endosome marker EGFP-Rab5 as well as the PI(3)P biosensor EGFP-2×FYVE. However, treatment with the phosphoinositide 3-kinase inhibitor wortmannin did not disrupt localization of mCherry-RavD to endosomal compartments, suggesting that RavD's interaction with PI(3)P is not necessary to anchor RavD to endosomal membranes. Using superresolution and immunogold transmission EM, we observed that, upon translocation into macrophages, RavD was retained onto the Legionella-containing vacuole and was also present on small vesicles adjacent to the vacuole. We also report that despite no detectable effects on intracellular growth of L. pneumophila within macrophages or amebae, the lack of RavD significantly increased the number of vacuoles that accumulate the late endosome/lysosome marker LAMP-1 during macrophage infection. Together, our findings suggest that, although not required for intracellular replication of L. pneumophila, RavD is a part of the molecular mechanism that steers the Legionella-containing vacuole away from endolysosomal maturation pathways.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7cee221ce4e6f655dc3155350cb034a0Test
https://doi.org/10.1074/jbc.ra118.007086Test

المؤلفون: Rebecca R. Noll, Colleen M. Pike, M. Ramona Neunuebel

مصطلحات موضوعية: Intracellular pathogen, 0303 health sciences, 03 medical and health sciences, biology, 030306 microbiology, biology.organism_classification, Legionella pneumophila, 030304 developmental biology, Microbiology

الوصف: Manipulation of host phosphoinositide lipids has emerged as a key survival strategy utilized by pathogenic bacteria to establish and maintain a replication-permissive compartment within eukaryotic host cells. The human pathogen, Legionella pneumophila, infects and proliferates within the lung’s innate immune cells causing severe pneumonia termed Legionnaires’ disease. This pathogen has evolved strategies to manipulate specific host components to construct its intracellular niche termed the Legionella-containing vacuole (LCV). Paramount to LCV biogenesis and maintenance is the spatiotemporal regulation of phosphoinositides, important eukaryotic lipids involved in cell signaling and membrane trafficking. Through a specialized secretion system, L. pneumophila translocates multiple proteins that target phosphoinositides in order to escape endolysosomal degradation. By specifically binding phosphoinositides, these proteins can anchor to the cytosolic surface of the LCV or onto specific host membrane compartments, to ultimately stimulate or inhibit encounters with host organelles. Here, we describe the bacterial proteins involved in binding and/or altering host phosphoinositide dynamics to support intracellular survival of L. pneumophila.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::88689cbb3d76ef4dfcfa6a112b5d8ab2Test
https://doi.org/10.5772/intechopen.89158Test

المؤلفون: Sean Lein, M. Ramona Neunuebel, Samual C. Allgood, Barbara P. Romero Dueñas, Colleen M. Pike, Rebecca R. Noll

المصدر: Frontiers in Cellular and Infection Microbiology, Vol 7 (2017)
Frontiers in Cellular and Infection Microbiology

مصطلحات موضوعية: 0301 basic medicine, Microbiology (medical), Immunology, lcsh:QR1-502, Endocytic recycling, Vacuole, Endocytosis, Legionella pneumophila, Microbiology, lcsh:Microbiology, endocytic recycling, 03 medical and health sciences, AnkX, Phagosome maturation, L. pneumophila, Original Research, 030102 biochemistry & molecular biology, biology, Effector, phagosome maturation, RAB1, biology.organism_classification, Cell biology, phosphocholination, 030104 developmental biology, Infectious Diseases, Biochemistry, Rab

الوصف: The facultative intracellular bacterium Legionella pneumophila proliferates within amoebae and human alveolar macrophages, and it is the causative agent of Legionnaires' disease, a life-threatening pneumonia. Within host cells, L. pneumophila establishes a replicative haven by delivering numerous effector proteins into the host cytosol, many of which target membrane trafficking by manipulating the function of Rab GTPases. The Legionella effector AnkX is a phosphocholine transferase that covalently modifies host Rab1 and Rab35. However, a detailed understanding of the biological consequence of Rab GTPase phosphocholination remains elusive. Here, we broaden the understanding of AnkX function by presenting three lines of evidence that it interferes with host endocytic recycling. First, using immunogold transmission electron microscopy, we determined that GFP-tagged AnkX ectopically produced in mammalian cells localizes at the plasma membrane and tubular membrane compartments, sites consistent with targeting the endocytic recycling pathway. Furthermore, the C-terminal region of AnkX was responsible for association with the plasma membrane, and we determined that this region was also able to bind the phosphoinositide lipids PI(3)P and PI(4)P in vitro. Second, we observed that mCherry-AnkX co-localized with Rab35, a regulator of recycling endocytosis and with major histocompatibility class I protein (MHC-I), a key immunoregulatory protein whose recycling from and back to the plasma membrane is Rab35-dependent. Third, we report that during infection of macrophages, AnkX is responsible for the disruption of endocytic recycling of transferrin, and AnkX's phosphocholination activity is critical for this function. These results support the hypothesis that AnkX targets endocytic recycling during host cell infection. Finally, we have demonstrated that the phosphocholination activity of AnkX is also critical for inhibiting fusion of the Legionella-containing vacuole (LCV) with lysosomes.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::650b223572ae47645efa91457c3de910Test