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1.
Proc Natl Acad Sci U S A ; 113(13): 3639-44, 2016 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-26957597

RESUMO

The human gut microbiome is a dynamic and densely populated microbial community that can provide important benefits to its host. Cooperation and competition for nutrients among its constituents only partially explain community composition and interpersonal variation. Notably, certain human-associated Bacteroidetes--one of two major phyla in the gut--also encode machinery for contact-dependent interbacterial antagonism, but its impact within gut microbial communities remains unknown. Here we report that prominent human gut symbionts persist in the gut through continuous attack on their immediate neighbors. Our analysis of just one of the hundreds of species in these communities reveals 12 candidate antibacterial effector loci that can exist in 32 combinations. Through the use of secretome studies, in vitro bacterial interaction assays and multiple mouse models, we uncover strain-specific effector/immunity repertoires that can predict interbacterial interactions in vitro and in vivo, and find that some of these strains avoid contact-dependent killing by accumulating immunity genes to effectors that they do not encode. Effector transmission rates in live animals can exceed 1 billion events per minute per gram of colonic contents, and multiphylum communities of human gut commensals can partially protect sensitive strains from these attacks. Together, these results suggest that gut microbes can determine their interactions through direct contact. An understanding of the strategies human gut symbionts have evolved to target other members of this community may provide new approaches for microbiome manipulation.


Assuntos
Microbioma Gastrointestinal/fisiologia , Animais , Bacteroides fragilis/genética , Bacteroides fragilis/imunologia , Bacteroides fragilis/fisiologia , Feminino , Microbioma Gastrointestinal/genética , Microbioma Gastrointestinal/imunologia , Genoma Bacteriano , Vida Livre de Germes , Humanos , Masculino , Camundongos , Modelos Animais , Filogenia , Simbiose/genética , Simbiose/imunologia , Simbiose/fisiologia , Sistemas de Secreção Tipo VI/genética , Sistemas de Secreção Tipo VI/imunologia , Sistemas de Secreção Tipo VI/fisiologia
2.
J Bacteriol ; 195(2): 287-96, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23144243

RESUMO

Pseudomonas syringae pv. tomato DC3000 produces the phytotoxin coronatine, a major determinant of the leaf chlorosis associated with DC3000 pathogenesis. The DC3000 PSPTO4723 (cmaL) gene is located in a genomic region encoding type III effectors; however, it promotes chlorosis in the model plant Nicotiana benthamiana in a manner independent of type III secretion. Coronatine is produced by the ligation of two moieties, coronafacic acid (CFA) and coronamic acid (CMA), which are produced by biosynthetic pathways encoded in separate operons. Cross-feeding experiments, performed in N. benthamiana with cfa, cma, and cmaL mutants, implicate CmaL in CMA production. Furthermore, analysis of bacterial supernatants under coronatine-inducing conditions revealed that mutants lacking either the cma operon or cmaL accumulate CFA rather than coronatine, supporting a role for CmaL in the regulation or biosynthesis of CMA. CmaL does not appear to regulate CMA production, since the expression of proteins with known roles in CMA production is unaltered in cmaL mutants. Rather, CmaL is needed for the first step in CMA synthesis, as evidenced by the fact that wild-type levels of coronatine production are restored to a ΔcmaL mutant when it is supplemented with 50 µg/ml l-allo-isoleucine, the starting unit for CMA production. cmaL is found in all other sequenced P. syringae strains with coronatine biosynthesis genes. This characterization of CmaL identifies a critical missing factor in coronatine production and provides a foundation for further investigation of a member of the widespread DUF1330 protein family.


Assuntos
Aminoácidos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Indenos/metabolismo , Isoleucina/metabolismo , Pseudomonas syringae/enzimologia , Deleção de Genes , Redes e Vias Metabólicas/genética , Doenças das Plantas/microbiologia , Pseudomonas syringae/genética , Pseudomonas syringae/metabolismo , Nicotiana/microbiologia
3.
J Am Soc Mass Spectrom ; 33(6): 1073-1076, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35545232

RESUMO

The gastrointestinal tract, including luminal content, harbors a complex mixture of microorganisms, host dietary content, and immune factors. Existing imaging approaches remove luminal content and only visualize small regions of the GI tract. Here, we demonstrate a workflow for multimodal imaging using matrix-assisted laser desorption/ionization imaging mass spectrometry, autofluorescence, and bright field microscopy for mapping intestinal tissue and luminal content. Results comparing tissue and luminal content in control murine tissue show both unique molecular and elemental distributions and abundances using multimodal protein, lipid, and elemental imaging. For instance, lipid PC(42:1) is 2× higher intensity in luminal content than tissue, while PC(32:0) is 80× higher intensity in tissue. Additionally, some ions such as the protein at m/z 3443 and the element manganese are only detected in luminal content, while the protein at m/z 8564 was only detected in tissue and phosphorus had 2× higher abundance in tissue. These data highlight the robust molecular information that can be gained from the gastrointestinal tract with the inclusion of luminal content.


Assuntos
Trato Gastrointestinal , Proteínas , Animais , Trato Gastrointestinal/química , Íons , Lipídeos/análise , Camundongos , Imagem Multimodal , Proteínas/análise , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
4.
Cell Rep ; 36(10): 109683, 2021 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-34496241

RESUMO

Clostridioides difficile is the leading cause of nosocomial intestinal infections in the United States. Ingested C. difficile spores encounter host bile acids and other cues that are necessary for germinating into toxin-producing vegetative cells. While gut microbiota disruption (often by antibiotics) is a prerequisite for C. difficile infection (CDI), the mechanisms C. difficile employs for colonization remain unclear. Here, we pioneered the application of imaging mass spectrometry to study how enteric infection changes gut metabolites. We find that CDI induces an influx of bile acids into the gut within 24 h of the host ingesting spores. In response, the host reduces bile acid biosynthesis gene expression. These bile acids drive C. difficile outgrowth, as mice receiving the bile acid sequestrant cholestyramine display delayed colonization and reduced germination. Our findings indicate that C. difficile may facilitate germination upon infection and suggest that altering flux through bile acid pathways can modulate C. difficile outgrowth in CDI-prone patients.


Assuntos
Antibacterianos/farmacologia , Ácidos e Sais Biliares/metabolismo , Clostridioides difficile/patogenicidade , Infecções por Clostridium/microbiologia , Animais , Infecções por Clostridium/metabolismo , Microbioma Gastrointestinal/fisiologia , Intestino Delgado/metabolismo , Intestino Delgado/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL
5.
Cell Host Microbe ; 28(3): 411-421.e6, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32526159

RESUMO

Clostridioides difficile infection of the colon leads to severe inflammation and damage to the gastrointestinal epithelium due to the production of potent toxins. This inflammatory tissue damage causes the liberation of high concentrations of host heme at infection sites. Here, we identify the C. difficile heme-sensing membrane protein system (HsmRA) and show that this operon induces a protective response that repurposes heme to counteract antimicrobial oxidative stress responses. HsmR senses vertebrate heme, leading to increased expression of the hsmRA operon and subsequent deployment of HsmA to capture heme and reduce redox damage caused by inflammatory mediators of protection and antibiotic therapy. Strains with inactivated hsmR or hsmA have increased sensitivity to redox-active compounds and reduced colonization persistence in a murine model of relapse C. difficile infection. These results define a mechanism exploited by C. difficile to repurpose toxic heme within the inflamed gut as a shield against antimicrobial compounds.


Assuntos
Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Clostridioides difficile/genética , Clostridioides difficile/metabolismo , Heme/metabolismo , Animais , Antibacterianos/farmacologia , Células Cultivadas , Clostridioides difficile/efeitos dos fármacos , Infecções por Clostridium/microbiologia , Regulação Bacteriana da Expressão Gênica , Interações Hospedeiro-Patógeno , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Neutrófilos , Óperon/genética , Estresse Oxidativo , RNA Bacteriano , Análise de Sequência de RNA
6.
Elife ; 72018 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-30226189

RESUMO

Human gut Bacteroides use surface-exposed lipoproteins to bind and metabolize complex polysaccharides. Although vitamins and other nutrients are also essential for commensal fitness, much less is known about how commensal bacteria compete with each other or the host for these critical resources. Unlike in Escherichia coli, transport loci for vitamin B12 (cobalamin) and other corrinoids in human gut Bacteroides are replete with conserved genes encoding proteins whose functions are unknown. Here we report that one of these proteins, BtuG, is a surface-exposed lipoprotein that is essential for efficient B12 transport in B. thetaiotaomicron. BtuG binds B12 with femtomolar affinity and can remove B12 from intrinsic factor, a critical B12 transport protein in humans. Our studies suggest that Bacteroides use surface-exposed lipoproteins not only for capturing polysaccharides, but also to acquire key vitamins in the gut.


Assuntos
Bacteroides/metabolismo , Membrana Celular/metabolismo , Trato Gastrointestinal/microbiologia , Lipoproteínas/metabolismo , Vitamina B 12/metabolismo , Sequência de Aminoácidos , Animais , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Transporte Biológico/genética , Corrinoides/metabolismo , Ligação Genética , Vida Livre de Germes , Humanos , Fator Intrínseco/metabolismo , Camundongos , Modelos Moleculares , Eletricidade Estática
7.
Nat Microbiol ; 2: 17026, 2017 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-28440278

RESUMO

Over the last decade, our appreciation for the contribution of resident gut microorganisms-the gut microbiota-to human health has surged. However, progress is limited by the sheer diversity and complexity of these microbial communities. Compounding the challenge, the majority of our commensal microorganisms are not close relatives of Escherichia coli or other model organisms and have eluded culturing and manipulation in the laboratory. In this Review, we discuss how over a century of study of the readily cultured, genetically tractable human gut Bacteroides has revealed important insights into the biochemistry, genomics and ecology that make a gut bacterium a gut bacterium. While genome and metagenome sequences are being produced at breakneck speed, the Bacteroides provide a significant 'jump-start' on uncovering the guiding principles that govern microbiota-host and inter-bacterial associations in the gut that will probably extend to many other members of this ecosystem.


Assuntos
Bacteroides , Metagenoma , Microbiota , Bacteroides/genética , Bacteroides/fisiologia , Firmicutes/genética , Firmicutes/fisiologia , Microbioma Gastrointestinal/genética , Microbioma Gastrointestinal/fisiologia , Trato Gastrointestinal/microbiologia , Trato Gastrointestinal/fisiologia , Genômica , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Simbiose
8.
Cell Host Microbe ; 16(2): 227-236, 2014 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-25070807

RESUMO

Bacteroidetes are a phylum of Gram-negative bacteria abundant in mammalian-associated polymicrobial communities, where they impact digestion, immunity, and resistance to infection. Despite the extensive competition at high cell density that occurs in these settings, cell contact-dependent mechanisms of interbacterial antagonism, such as the type VI secretion system (T6SS), have not been defined in this group of organisms. Herein we report the bioinformatic and functional characterization of a T6SS-like pathway in diverse Bacteroidetes. Using prominent human gut commensal and soil-associated species, we demonstrate that these systems localize dynamically within the cell, export antibacterial proteins, and target competitor bacteria. The Bacteroidetes system is a distinct pathway with marked differences in gene content and high evolutionary divergence from the canonical T6S pathway. Our findings offer a potential molecular explanation for the abundance of Bacteroidetes in polymicrobial environments, the observed stability of Bacteroidetes in healthy humans, and the barrier presented by the microbiota against pathogens.


Assuntos
Antibiose , Sistemas de Secreção Bacterianos , Flavobacterium/fisiologia , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Genes Bacterianos , Família Multigênica , Filogenia
9.
J Neuroimmunol ; 255(1-2): 60-9, 2013 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-23269203

RESUMO

Multiple sclerosis (MS) is an autoimmune disease that is mediated by myelin-reactive T cells resulting in CNS demyelination, however the mechanisms that control their activation are unclear. Mice that are transgenic for a myelin proteolipid protein (PLP)-specific TCR spontaneously develop experimental autoimmune encephalomyelitis (EAE), the animal model of MS. They mimic the spontaneous onset of MS and thus offer the unique opportunity to investigate the mechanisms that may contribute to the development of spontaneous CNS autoimmunity. MyD88 is an adaptor protein that mediates signal transduction by TLRs, IL-1R and IL-18R, resulting in the activation of innate immune cells, including DCs. We investigated the requirement of MyD88 in the pathogenesis of spontaneous EAE in PLP TCR transgenic SJL mice. We show that genetic loss of MyD88 does not intrinsically preclude development of spontaneous EAE and autoimmune demyelination in these mice. EAE was associated with functionally mature peripheral DCs that promoted superior PLP-specific Th1 and Th17 responses compared to those from disease-free mice. Together, our data suggest that MyD88-independent innate immune signaling critically contributes to priming of myelin-reactive T cells and development of spontaneous EAE in MyD88-deficient PLP TCR transgenic mice.


Assuntos
Encefalomielite Autoimune Experimental/imunologia , Encefalomielite Autoimune Experimental/metabolismo , Esclerose Múltipla/imunologia , Esclerose Múltipla/metabolismo , Fator 88 de Diferenciação Mieloide/fisiologia , Animais , Doenças Desmielinizantes/genética , Doenças Desmielinizantes/imunologia , Doenças Desmielinizantes/metabolismo , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/genética , Feminino , Imunidade Inata/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Esclerose Múltipla/genética , Fator 88 de Diferenciação Mieloide/deficiência , Fator 88 de Diferenciação Mieloide/genética
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