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1.
World J Microbiol Biotechnol ; 35(7): 105, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31267317

RESUMO

Pseudocercospora fijiensis causes black Sigatoka disease, the most important threat to banana. The cell wall is crucial for fungal biological processes, including pathogenesis. Here, we performed cell wall proteomics analyses of two P. fijiensis strains, the highly virulent Oz2b, and the less virulent C1233 strains. Strains were starved from nitrogen to mimic the host environment. Interestingly, in vitro cultures of the C1233 strain grew faster than Oz2b in PDB medium, suggesting that C1233 survives outside the host better than the highly virulent Oz2b strain. Both strains were submitted to nitrogen starvation and the cell wall proteins were isolated and subjected to nano-HPLC-MS/MS. A total of 2686 proteins were obtained from which only 240 had a known function and thus, bioinformatics analyses were performed on this group. We found that 90 cell wall proteins were shared by both strains, 21 were unique for Oz2b and 39 for C1233. Shared proteins comprised 24 pathogenicity factors, including Avr4 and Ecp6, two effectors from P. fijiensis, while the unique proteins comprised 16 virulence factors in C1233 and 11 in Oz2b. The P. fijiensis cell wall proteome comprised canonical proteins, but thirty percent were atypical, a feature which in other phytopathogens has been interpreted as contamination. However, a comparison with the identities of atypical proteins in other reports suggests that the P. fijiensis proteins we detected were not contaminants. This is the first proteomics analysis of the P. fijiensis cell wall and our results expands the understanding of the fundamental biology of fungal phytopathogens and will help to decipher the molecular mechanisms of pathogenesis and virulence in P. fijiensis.


Assuntos
Ascomicetos/genética , Ascomicetos/metabolismo , Parede Celular/genética , Parede Celular/metabolismo , Proteoma , Fatores de Virulência/genética , Fatores de Virulência/metabolismo , Ascomicetos/isolamento & purificação , Ascomicetos/patogenicidade , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Genes Fúngicos/genética , Genoma Fúngico , Musa/microbiologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Espectrometria de Massas em Tandem , Virulência
2.
Nat Commun ; 10(1): 2763, 2019 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-31235751

RESUMO

Multidrug resistant (MDR) Acinetobacter baumannii poses a growing threat to global health. Research on Acinetobacter pathogenesis has primarily focused on pneumonia and bloodstream infections, even though one in five A. baumannii strains are isolated from urinary sites. In this study, we highlight the role of A. baumannii as a uropathogen. We develop the first A. baumannii catheter-associated urinary tract infection (CAUTI) murine model using UPAB1, a recent MDR urinary isolate. UPAB1 carries the plasmid pAB5, a member of the family of large conjugative plasmids that represses the type VI secretion system (T6SS) in multiple Acinetobacter strains. pAB5 confers niche specificity, as its carriage improves UPAB1 survival in a CAUTI model and decreases virulence in a pneumonia model. Comparative proteomic and transcriptomic analyses show that pAB5 regulates the expression of multiple chromosomally-encoded virulence factors besides T6SS. Our results demonstrate that plasmids can impact bacterial infections by controlling the expression of chromosomal genes.


Assuntos
Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/patogenicidade , Infecções Relacionadas a Cateter/microbiologia , Plasmídeos/genética , Pneumonia Bacteriana/microbiologia , Infecções Urinárias/microbiologia , Infecções por Acinetobacter/epidemiologia , Acinetobacter baumannii/genética , Acinetobacter baumannii/isolamento & purificação , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Infecções Relacionadas a Cateter/epidemiologia , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla/genética , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica , Humanos , Camundongos , Pneumonia Bacteriana/epidemiologia , Proteômica , Estudos Retrospectivos , Sistemas de Secreção Tipo VI/genética , Sistemas de Secreção Tipo VI/metabolismo , Cateteres Urinários/efeitos adversos , Cateteres Urinários/microbiologia , Sistema Urinário/microbiologia , Infecções Urinárias/epidemiologia , Virulência/genética , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
3.
Microbiol Immunol ; 63(7): 251-260, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31166029

RESUMO

Streptococcus mutans is a cariogenic bacterium that localizes in the oral cavity. Glycyrrhetinic acid (GRA) is a major component of licorice extract. GRA and several derivatives, including disodium succinoyl glycyrrhetinate (GR-SU), are known to have anti-inflammatory effects in humans. In this study, the antimicrobial effect of GRA and its derivatives against the S. mutans UA159 strain were investigated. Minimum inhibitory concentrations (MICs) of GRA and GR-SU showed antibacterial activity against the S. mutans strain, whereas other tested derivatives did not. Because GR-SU is more soluble than GRA, GR-SU was used for further experiments. The antibacterial activity of GR-SU against 100 S. mutans strains was evaluated and it was found that all strains are susceptible to GR-SU, with MIC values below 256 µg/mL. A cell viability assay showed that GR-SU has a bacteriostatic effect on S. mutans cells. As to growth kinetics, sub-MICs of GR-SU inhibited growth. The effect of GR-SU on S. mutans virulence was then investigated. GR-SU at sub-MICs suppresses biofilm formation. Additionally, GR-SU greatly suppresses the pH drop caused by the addition of glucose and glucose-induced expression of the genes responsible for acid production (ldh and pykF) and tolerance (aguD and atpD). Additionally, expression of enolase, which is responsible for the carbohydrate phosphotransferase system, was not increased in the presence of GR-SU, indicating that GR-SU suppresses incorporation of sugars into S. mutans. In conclusion, GR-SU has antibacterial activity against S. mutans and also decreases S. mutans virulence.


Assuntos
Antibacterianos/farmacologia , Ácido Glicirretínico/farmacologia , Glycyrrhiza/química , Extratos Vegetais/farmacologia , Streptococcus mutans/efeitos dos fármacos , Antibacterianos/química , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Genes Bacterianos/genética , Glucose/metabolismo , Ácido Glicirretínico/química , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Extratos Vegetais/química , Streptococcus mutans/genética , Streptococcus mutans/crescimento & desenvolvimento , Virulência , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
4.
Microbiol Res ; 223-225: 88-98, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31178056

RESUMO

CodY and (p)ppGpp synthetases are two important global regulators of bacteria. In some pathogens, such as Listeria monocytogenes, the GTP pool links these two regulatory systems, and introducing a codY mutant into the ΔrelA strain restored the pathogenicity of the attenuated ΔrelA mutant. In previous studies, we identified the (p)ppGpp synthetases (RelA and RelQ) and CodY of Streptococcus suis. To understand the interrelationships between these two regulators in S. suis, a ΔrelAΔrelQΔcodY mutant was constructed, and its growth, morphology, and pathogenicity were evaluated. Compared with ΔrelAΔrelQ, ΔcodY, its growth was very slow, but its chain length was partly restored to the wild-type length and its capsule became thick and rough. The adherence, invasion ability, and resistance to whole-blood killing in vitro of ΔrelAΔrelQΔcodY and its lethality and colonization ability in mice were clearly reduced, which differs from the effects of these mutations in L. monocytogenes. An analysis of gene expression showed that CodY interacted with the relA promoter in a GTP-independent manner to positively regulate the expression of relA. The introduction of a codY mutant into the ΔrelAΔrelQ strain further reduced the expression of virulence factors, which suggests a novel interaction between the (p)ppGpp synthetases and CodY. This study extends our understanding of the relationship between the (p)ppGpp-mediated stringent response and the regulation of CodY in S. suis.


Assuntos
Regulação Bacteriana da Expressão Gênica , Ligases/metabolismo , Streptococcus suis/citologia , Streptococcus suis/metabolismo , Streptococcus suis/patogenicidade , Fatores de Transcrição/metabolismo , Transcriptoma , Adesinas Bacterianas/genética , Animais , Proteínas de Bactérias/genética , Modelos Animais de Doenças , Feminino , Guanosina Trifosfato/metabolismo , Ligases/genética , Listeria monocytogenes/genética , Listeria monocytogenes/metabolismo , Listeria monocytogenes/patogenicidade , Camundongos , Mutação , Regiões Promotoras Genéticas , Infecções Estreptocócicas/microbiologia , Streptococcus suis/genética , Fatores de Transcrição/genética , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
5.
MBio ; 10(2)2019 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-31040242

RESUMO

Toxoplasma gondii is an obligate intracellular parasite that establishes a favorable environment in the host cells in which it replicates. We have previously reported that it uses MYR-dependent translocation of dense granule proteins to elicit a key set of host responses related to the cell cycle, specifically, E2F transcription factor targets, including cyclin E. We report here the identification of a novel Toxoplasma effector protein that is exported from the parasitophorous vacuole in a MYR1-dependent manner and localizes to the host's nucleus. Parasites lacking this inducer of host cyclin E (HCE1) are unable to modulate E2F transcription factor target genes and exhibit a substantial growth defect. Immunoprecipitation of HCE1 from infected host cells showed that HCE1 efficiently binds elements of the cyclin E regulatory complex, namely, DP1 and its partners E2F3 and E2F4. Expression of HCE1 in Neospora caninum, or in uninfected human foreskin fibroblasts (HFFs), showed localization of the expressed protein to the host nuclei and strong cyclin E upregulation. Thus, HCE1 is a novel effector protein that is necessary and sufficient to impact the E2F axis of transcription, resulting in co-opting of host functions to the advantage of Toxoplasma IMPORTANCE Like most Apicomplexan parasites, Toxoplasma gondii has the remarkable ability to invade and establish a replicative niche within another eukaryotic cell, in this case, any of a large number of cell types in almost any warm-blooded animals. Part of the process of establishing this niche is the export of effector proteins to co-opt host cell functions in favor of the parasite. Here we identify a novel effector protein, HCE1, that the parasites export into the nucleus of human cells, where it modulates the expression of multiple genes, including the gene encoding cyclin E, one of the most crucial proteins involved in controlling when and whether a human cell divides. We show that HCE1 works through binding to specific transcription factors, namely, E2F3, E2F4, and DP1, that normally carefully regulate these all-important pathways. This represents a new way in which these consummately efficient infectious agents co-opt the human cells that they so efficiently grow within.


Assuntos
Ciclina E/biossíntese , Regulação da Expressão Gênica , Interações Hospedeiro-Patógeno , Miosina Tipo I/metabolismo , Proteínas de Protozoários/metabolismo , Toxoplasma/fisiologia , Fatores de Virulência/metabolismo , Células Cultivadas , Fatores de Transcrição E2F/metabolismo , Fibroblastos/parasitologia , Humanos , Ligação Proteica , Transporte Proteico
6.
Nat Commun ; 10(1): 1967, 2019 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-31036849

RESUMO

Autotransporters are the largest family of outer membrane and secreted proteins in Gram-negative bacteria. Most autotransporters are localised to the bacterial surface where they promote colonisation of host epithelial surfaces. Here we present the crystal structure of UpaB, an autotransporter that is known to contribute to uropathogenic E. coli (UPEC) colonisation of the urinary tract. We provide evidence that UpaB can interact with glycosaminoglycans and host fibronectin. Unique modifications to its core ß-helical structure create a groove on one side of the protein for interaction with glycosaminoglycans, while the opposite face can bind fibronectin. Our findings reveal far greater diversity in the autotransporter ß-helix than previously thought, and suggest that this domain can interact with host macromolecules. The relevance of these interactions during infection remains unclear.


Assuntos
Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Glicosaminoglicanos/metabolismo , Escherichia coli Uropatogênica/metabolismo , Adesinas Bacterianas/química , Adesinas Bacterianas/metabolismo , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/metabolismo , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Fatores de Virulência/química , Fatores de Virulência/metabolismo
7.
Nat Commun ; 10(1): 2334, 2019 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-31133642

RESUMO

Pseudomonas aeruginosa, a significant opportunistic pathogen, can participate in inter-species communication through signaling by cis-2-unsaturated fatty acids of the diffusible signal factor (DSF) family. Sensing these signals leads to altered biofilm formation and increased tolerance to various antibiotics, and requires the histidine kinase PA1396. Here, we show that the membrane-associated sensory input domain of PA1396 has five transmembrane helices, two of which are required for DSF sensing. DSF binding is associated with enhanced auto-phosphorylation of PA1396 incorporated into liposomes. Further, we examined the ability of synthetic DSF analogues to modulate or inhibit PA1396 activity. Several of these analogues block the ability of DSF to trigger auto-phosphorylation and gene expression, whereas others act as inverse agonists reducing biofilm formation and antibiotic tolerance, both in vitro and in murine infection models. These analogues may thus represent lead compounds to develop novel adjuvants improving the efficacy of existing antibiotics.


Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Ácidos Graxos Insaturados/metabolismo , Histidina Quinase/metabolismo , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/fisiologia , Animais , Antibacterianos/uso terapêutico , Proteínas de Bactérias/genética , Biofilmes/efeitos dos fármacos , Modelos Animais de Doenças , Farmacorresistência Bacteriana , Feminino , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/imunologia , Histidina Quinase/genética , Humanos , Lipossomos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Testes de Sensibilidade Microbiana , Mutagênese , Fosforilação , Polimixinas/farmacologia , Polimixinas/uso terapêutico , Infecções por Pseudomonas/imunologia , Infecções por Pseudomonas/microbiologia , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
8.
Fungal Biol ; 123(5): 423-430, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31053331

RESUMO

Plant pathogens employ effectors as molecular weapons to manipulate host immunity and facilitate colonization. Fusarium oxysporum f. sp. cubense is the agent of wilt disease in banana plantlets and four races of the pathogen have been identified based on the cultivar specificity. A total of 9 SIX genes have been detected in the genome of Foc TR4 and 6 genes detected in Foc1. Among these SIX genes, SIX2 and SIX8 are only detected in Foc TR4, not identified in Foc1. Expression profiles analysis revealed that SIX genes of Foc TR4 are highly induced after inoculation to Cavendish banana plantlets. Virulence analysis of the SIX2 and SIX8 knock-out mutants showed that SIX8 is required for the virulence of Foc TR4 while SIX2 has no obvious functions. Over expression of SIX8-FLAG proteins in the SIX8 knock-out mutant partly restored the virulence. Western blot analysis suggested that SIX8 could be secreted into the extracellular space and a signal peptide resided the N-terminal polypeptide sequence. This study provides some clues for further research on mechanism of SIX8 in regulating virulence of Foc TR4.


Assuntos
Proteínas Fúngicas/metabolismo , Fusarium/patogenicidade , Musa/microbiologia , Doenças das Plantas/microbiologia , Fatores de Virulência/metabolismo , Proteínas Fúngicas/genética , Fusarium/genética , Fusarium/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Técnicas de Inativação de Genes , Teste de Complementação Genética , Fatores de Virulência/genética
9.
J Microbiol ; 57(7): 618-625, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31054133

RESUMO

Quorum sensing (QS) regulates virulence factor expression in Pseudomonas aeruginosa. Inhibiting the QS-controlled virulence factors without inhibiting the growth of P. aeruginosa is a promising approach for overcoming the widespread resistance of P. aeruginosa. This study was proposed to investigate the effects of two novel synthetic peptides on the biofilm development and virulence factor production of P. aeruginosa. The tested strain was P. aeruginosa PAO1. The results indicated that both of the synthetic peptides (LIVRHK and LIVRRK) inhibited (P < 0.05) the formation of biofilms and the production of virulence factors, including pyocyanin, protease, and rhamnolipids, without inhibiting the growth of PAO1. Additionally, we detected transcriptional changes related to QS and found a significant reduction in the levels of gene expression of lasI, lasR, rhlI, and rhlR. This study demonstrates that LIVRRK and LIVRHK are novel synthetic peptides that can act as potent inhibitors of QS-regulated virulence factors in P. aeruginosa. Moreover, these synthetic peptides have potential applications in the treatment of biofilmrelated diseases. Both peptides may be able to control chronic infections and biofilm-associated problems of P. aeruginosa.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Peptídeos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Percepção de Quorum/efeitos dos fármacos , Fatores de Virulência/metabolismo
10.
Emerg Microbes Infect ; 8(1): 734-748, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31130074

RESUMO

Many pathogens infect hosts through various immune evasion strategies. However, the molecular mechanisms by which pathogen proteins modulate and evade the host immune response remain unclear. Enterohemorrhagic Escherichia coli (EHEC) is a pathological strain that can induce mitogen-activated protein (MAP) kinase (Erk, Jnk and p38 MAPK) and NF-κB pathway activation and proinflammatory cytokine production, which then causes diarrheal diseases such as hemorrhagic colitis and hemolytic uremic syndrome. Transforming growth factor ß-activated kinase-1 (TAK1) is a key regulator involved in distinct innate immune signalling pathways. Here we report that EHEC translocated intimin receptor (Tir) protein inhibits the expression of EHEC-induced proinflammatory cytokines by interacting with the host tyrosine phosphatase SHP-1, which is dependent on the phosphorylation of immunoreceptor tyrosine-based inhibition motifs (ITIMs). Mechanistically, the association of EHEC Tir with SHP-1 facilitated the recruitment of SHP-1 to TAK1 and inhibited TAK1 phosphorylation, which then negatively regulated K63-linked polyubiquitination of TAK1 and downstream signal transduction. Taken together, these results suggest that EHEC Tir negatively regulates proinflammatory responses by inhibiting the activation of TAK1, which is essential for immune evasion and could be a potential target for the treatment of bacterial infection.


Assuntos
Escherichia coli Êntero-Hemorrágica/patogenicidade , Infecções por Escherichia coli/fisiopatologia , Proteínas de Escherichia coli/metabolismo , Interações Hospedeiro-Patógeno , Evasão da Resposta Imune , MAP Quinase Quinase Quinases/antagonistas & inibidores , Receptores de Superfície Celular/metabolismo , Fatores de Virulência/metabolismo , Animais , Infecções por Escherichia coli/microbiologia , Células HEK293 , Humanos , Macrófagos Peritoneais , Camundongos , Camundongos Endogâmicos C57BL , Ligação Proteica , Proteína Tirosina Fosfatase não Receptora Tipo 6/metabolismo , Células RAW 264.7
11.
MBio ; 10(2)2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-31015326

RESUMO

Chlamydia trachomatis is the most common bacterial cause of sexually transmitted infections. C. trachomatis sexually transmitted infections are commonly asymptomatic, implying a pathogenic strategy for the evasion of innate inflammatory immune responses, a paradox as the C. trachomatis outer membrane contains lipopolysaccharide (LPS), a known potent agonist of inflammatory innate immunity. Here, we studied the ability of chlamydial LPS to activate the proinflammatory canonical and noncanonical inflammasome pathways in mouse bone marrow-derived macrophages (BMDM). We show, in comparison to Escherichia coli LPS, that C. trachomatis LPS-treated BMDM produce significantly less IL-6, TNF, and type I interferon mRNA, indicating that downstream signaling through the canonical TLR4 myddosome and triffosome pathways was blocked. We confirmed this in C. trachomatis LPS-treated BMDM by showing the lack of NF-κB and IRF3 phosphorylation, respectively. Interestingly, C. trachomatis LPS bound CD14 and promoted its endocytosis; however; it did not promote efficient TLR4/MD-2 dimerization or endocytosis, known requirements for myddosome and triffosome signaling pathways. We further found that transfection of BMDM with C. trachomatis LPS did not cause pyroptotic cell ballooning, cytotoxicity, or IL-1ß secretion, all characteristic features of noncanonical inflammasome activation. Western blotting confirmed that cytosolic C. trachomatis LPS failed to signal through caspase-11, as shown by the lack of gasdermin D, caspase-1, or IL-1ß proteolytic cleavage. We propose that chlamydiae evolved a unique LPS structure as a pathogenic strategy to avoid canonical and noncanonical innate immune signaling and conclude that this strategy might explain the high incidence of asymptomatic infections.IMPORTANCE Chlamydia trachomatis is the most common bacterial cause of sexually transmitted infections (STI). C. trachomatis STI are commonly asymptomatic, implying a pathogenic strategy for the evasion of innate inflammatory immune responses, a paradox as the C. trachomatis outer membrane contains lipopolysaccharide (LPS), a known potent agonist of inflammatory innate immunity. Here, we found that C. trachomatis LPS is not capable of engaging the canonical TLR4/MD-2 or noncanonical caspase-11 inflammatory pathways. The inability of C. trachomatis LPS to trigger innate immunity inflammatory pathways is related to its unique fatty acid structure. Evolutionary modification of the LPS structure likely evolved as a pathogenic strategy to silence innate host defense mechanisms. The findings might explain the high incidence of asymptomatic chlamydial genital infection.


Assuntos
Chlamydia trachomatis/imunologia , Chlamydia trachomatis/patogenicidade , Evasão da Resposta Imune , Imunidade Inata , Lipopolissacarídeos/metabolismo , Fatores de Virulência/metabolismo , Animais , Citocinas/biossíntese , Escherichia coli/imunologia , Escherichia coli/patogenicidade , Perfilação da Expressão Gênica , Macrófagos/imunologia , Camundongos Endogâmicos C57BL
12.
MBio ; 10(2)2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-31015329

RESUMO

Escherichia coli is a major cause of bloodstream and urinary tract infections globally. The wide dissemination of multidrug-resistant (MDR) strains of extraintestinal pathogenic E. coli (ExPEC) poses a rapidly increasing public health burden due to narrowed treatment options and increased risk of failure to clear an infection. Here, we present a detailed population genomic analysis of the ExPEC ST131 clone, in which we seek explanations for its success as an emerging pathogenic strain beyond the acquisition of antimicrobial resistance (AMR) genes. We show evidence for evolution toward separate ecological niches for the main clades of ST131 and differential evolution of anaerobic metabolism, key colonization, and virulence factors. We further demonstrate that negative frequency-dependent selection acting across accessory loci is a major mechanism that has shaped the population evolution of this pathogen.IMPORTANCE Infections with multidrug-resistant (MDR) strains of Escherichia coli are a significant global public health concern. To combat these pathogens, we need a deeper understanding of how they evolved from their background populations. By understanding the processes that underpin their emergence, we can design new strategies to limit evolution of new clones and combat existing clones. By combining population genomics with modelling approaches, we show that dominant MDR clones of E. coli are under the influence of negative frequency-dependent selection, preventing them from rising to fixation in a population. Furthermore, we show that this selection acts on genes involved in anaerobic metabolism, suggesting that this key trait, and the ability to colonize human intestinal tracts, is a key step in the evolution of MDR clones of E. coli.


Assuntos
Farmacorresistência Bacteriana Múltipla , Infecções por Escherichia coli/microbiologia , Evolução Molecular , Escherichia coli Extraintestinal Patogênica/patogenicidade , Variação Genética , Seleção Genética , Fatores de Virulência/metabolismo , Escherichia coli Extraintestinal Patogênica/efeitos dos fármacos , Escherichia coli Extraintestinal Patogênica/genética , Genótipo , Humanos , Fatores de Virulência/genética
13.
Microbiol Spectr ; 7(2)2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30953429

RESUMO

Shigella is a genus of Gram-negative enteropathogens that have long been, and continue to be, an important public health concern worldwide. Over the past several decades, Shigella spp. have also served as model pathogens in the study of bacterial pathogenesis, and Shigella flexneri has become one of the best-studied pathogens on a molecular, cellular, and tissue level. In the arms race between Shigella and the host immune system, Shigella has developed highly sophisticated mechanisms to subvert host cell processes in order to promote infection, escape immune detection, and prevent bacterial clearance. Here, we give an overview of Shigella pathogenesis while highlighting innovative techniques and methods whose application has significantly advanced our understanding of Shigella pathogenesis in recent years.


Assuntos
Disenteria Bacilar/imunologia , Interações Hospedeiro-Patógeno/imunologia , Shigella/imunologia , Shigella/patogenicidade , Imunidade Adaptativa , Adesinas Bacterianas , Proteínas de Bactérias , Citosol/microbiologia , Disenteria Bacilar/microbiologia , Células Epiteliais/metabolismo , Células Epiteliais/microbiologia , Microbioma Gastrointestinal , Humanos , Evasão da Resposta Imune , Shigella flexneri/imunologia , Shigella flexneri/patogenicidade , Sistemas de Secreção Tipo III , Virulência , Fatores de Virulência/metabolismo
14.
Microbiol Res ; 222: 43-51, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30928029

RESUMO

Vibrio parahaemolyticus is a Gram-negative halophilic bacterium that is mainly distributed in the seafood such as fish, shrimps and shellfish throughout the world. V. parahaemolyticus can cause diseases in marine aquaculture, leading to huge economic losses to the aquaculture industry. More importantly, it is also the leading cause of seafood-borne diarrheal disease in humans worldwide. With the development of animal model, next-generation sequencing as well as biochemical and cell biological technologies, deeper understanding of the virulence factors and pathogenic mechanisms of V. parahaemolyticus has been gained. As a globally transmitted pathogen, the pathogenicity of V. parahaemolyticus is closely related to a variety of virulence factors. This article comprehensively reviewed the molecular mechanisms of eight types of virulence factors: hemolysin, type III secretion system, type VI secretion system, adhesion factor, iron uptake system, lipopolysaccharide, protease and outer membrane proteins. This review comprehensively summarized our current understanding of the virulence factors in V. parahaemolyticus, which are potentially new targets for the development of therapeutic and preventive strategies.


Assuntos
Vibrioses/microbiologia , Vibrio parahaemolyticus/patogenicidade , Fatores de Virulência/metabolismo , Adesinas Bacterianas , Animais , Proteínas da Membrana Bacteriana Externa , Proteínas de Bactérias , Proteínas Hemolisinas , Humanos , Ferro/metabolismo , Lipopolissacarídeos , Peptídeo Hidrolases , Alimentos Marinhos/microbiologia , Sistemas de Secreção Tipo III , Sistemas de Secreção Tipo VI , Vibrioses/transmissão , Vibrioses/veterinária , Virulência
15.
Microbiol Spectr ; 7(2)2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-31025624

RESUMO

Staphylococcus aureus is clearly the most pathogenic member of the Staphylococcaceae. This is in large part due to the acquisition of an impressive arsenal of virulence factors that are coordinately regulated by a series of dedicated transcription factors. What is becoming more and more appreciated in the field is the influence of the metabolic state of S. aureus on the activity of these virulence regulators and their roles in modulating metabolic gene expression. Here I highlight recent advances in S. aureus metabolism as it pertains to virulence. Specifically, mechanisms of nutrient acquisition are outlined including carbohydrate and non-carbohydrate carbon/energy sources as well as micronutrient (Fe, Mn, Zn and S) acquisition. Additionally, energy producing strategies (respiration versus fermentation) are discussed and put in the context of pathogenesis. Finally, transcriptional regulators that coordinate metabolic gene expression are outlined, particularly those that affect the activities of major virulence factor regulators. This chapter essentially connects many recent observations that link the metabolism of S. aureus to its overall pathogenesis and hints that the mere presence of a plethora of virulence factors may not entirely explain the extraordinary pathogenic potential of S. aureus.


Assuntos
Staphylococcus aureus/metabolismo , Staphylococcus aureus/patogenicidade , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Metabolismo dos Carboidratos , Fermentação , Humanos , Micronutrientes/metabolismo , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Fatores de Transcrição/metabolismo , Virulência , Fatores de Virulência/metabolismo
16.
BMC Genomics ; 20(1): 271, 2019 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-30953471

RESUMO

BACKGROUND: Wild birds, in particular pigeons are considered a natural reservoir for stx2f-carrying E. coli. An extensive comparison of isolates from pigeons and humans from the same region is lacking, which hampers justifiable conclusions on the epidemiology of these pathogens. Over two hundred human and pigeon stx2f-carrying E. coli isolates predominantly from the Netherlands were analysed by whole genome sequencing and comparative genomic analysis including in silico MLST, serotyping, virulence genes typing and whole genome MLST (wgMLST). RESULTS: Serotypes and sequence types of stx2f-carrying E. coli showed a strong non-random distribution among the human and pigeon isolates with O63:H6/ST583, O113:H6/ST121 and O125:H6/ST583 overrepresented among the human isolates and not found among pigeons. Pigeon isolates were characterized by an overrepresentation of O4:H2/ST20 and O45:H2/ST20. Nearly all isolates harboured the locus of enterocyte effacement (LEE) but different eae and tir subtypes were non-randomly distributed among human and pigeon isolates. Phylogenetic core genome comparison demonstrated that the pigeon isolates and clinical isolates largely occurred in separated clusters. In addition, serotypes/STs exclusively found among humans generally were characterized by high level of clonality, smaller genome sizes and lack of several non-LEE-encoded virulence genes. A bundle-forming pilus operon, including bfpA, indicative for typical enteropathogenic E. coli (tEPEC) was demonstrated in 72.0% of the stx2f-carrying serotypes but with distinct operon types between the main pigeon and human isolate clusters. CONCLUSIONS: Comparative genomics revealed that isolates from mild human disease are dominated by serotypes not encountered in the pigeon reservoir. It is therefore unlikely that zoonotic transmission from this reservoir plays an important role in the contribution to the majority of human disease associated with stx2f-producing E. coli in the Netherlands. Unexpectedly, this study identified the common occurrence of STEC2f/tEPEC hybrid pathotype in various serotypes and STs. Further research should focus on the possible role of human-to-human transmission of Stx2f-producing E. coli.


Assuntos
Doenças das Aves/epidemiologia , Escherichia coli Enteropatogênica/patogenicidade , Infecções por Escherichia coli/epidemiologia , Proteínas de Escherichia coli/metabolismo , Genômica/métodos , Toxina Shiga/metabolismo , Fatores de Virulência/metabolismo , Animais , Columbidae , Escherichia coli Enteropatogênica/classificação , Infecções por Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Genoma Bacteriano , Humanos , Filogenia , Toxina Shiga/genética , Fatores de Virulência/genética
17.
Appl Microbiol Biotechnol ; 103(10): 4203-4215, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30972460

RESUMO

The TonB system functions in iron transport and has been identified in certain Gram-negative bacteria. Recently, we reported three TonB systems in the Aeromonas hydrophila Chinese epidemic strain NJ-35, but the functions of these systems have not been thoroughly elucidated to date. In this study, we investigated the role of these TonB systems in A. hydrophila iron utilization and virulence. We found that tonB1 and tonB2 were preferentially transcribed in iron-chelated conditions, where gene expression levels were approximately 8- and 68-fold higher compared with iron-rich conditions, respectively; tonB3 was consistently transcribed at a low level under iron-repleted and iron-depleted conditions. Only the TonB2 system was required to utilize iron-binding proteins. The tonB123 mutant showed increased susceptibility to erythromycin and roxithromycin. In addition, all three tonB genes were involved in A. hydrophila virulence in zebrafish, and various phenotypes associated with environmental survival were changed with varying degrees in each tonB mutant. TonB2 plays a relatively major role in adhesion, motility, and biofilm formation, while TonB3 is more involved in the anti-phagocytosis of A. hydrophila. In each observed phenotype, no significant difference was found between the single- and double-deletion mutants, whereas the triple-deletion mutant exhibited the most serious defects, indicating that all three TonB systems of A. hydrophila coordinately complement one another. In conclusion, this study elucidates the importance of TonB in iron acquisition and virulence of A. hydrophila, which lays the foundation for future studies regarding the survival mechanisms of this bacterium in iron-restricted environments.


Assuntos
Aeromonas hydrophila/isolamento & purificação , Aeromonas hydrophila/patogenicidade , Proteínas de Bactérias/metabolismo , Ferro/metabolismo , Proteínas de Membrana/metabolismo , Fatores de Virulência/metabolismo , Animais , Aquicultura , Proteínas de Bactérias/genética , China , Modelos Animais de Doenças , Deleção de Genes , Perfilação da Expressão Gênica , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Proteínas de Membrana/genética , Análise de Sobrevida , Oligoelementos/metabolismo , Virulência , Fatores de Virulência/genética , Peixe-Zebra
18.
EcoSal Plus ; 8(2)2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30942149

RESUMO

Type III protein secretion systems (T3SSs), or injectisomes, are multiprotein nanomachines present in many Gram-negative bacteria that have a sustained long-standing close relationship with a eukaryotic host. These secretion systems have evolved to modulate host cellular functions through the activity of the effector proteins they deliver. To reach their destination, T3SS effectors must cross the multibarrier bacterial envelope and the eukaryotic cell membrane. Passage through the bacterial envelope is mediated by the needle complex, a central component of T3SSs that expands both the inner and outer membranes of Gram-negative bacteria. A set of T3SS secreted proteins, known as translocators, form a channel in the eukaryotic plasma membrane through which the effector proteins are delivered to reach the host cell cytosol. While the effector proteins are tailored to the specific lifestyle of the bacterium that encodes them, the injectisome is conserved among the different T3SSs. The central role of T3SSs in pathogenesis and their high degree of conservation make them a desirable target for the development of antimicrobial therapies against several important bacterial pathogens.


Assuntos
Proteínas de Bactérias/metabolismo , Células Eucarióticas/microbiologia , Bactérias Gram-Negativas/patogenicidade , Interações Hospedeiro-Patógeno , Sistemas de Secreção Tipo III/metabolismo , Fatores de Virulência/metabolismo , Proteínas de Bactérias/genética , Transporte Proteico , Sistemas de Secreção Tipo III/genética , Fatores de Virulência/genética
19.
Microb Pathog ; 131: 186-196, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30980878

RESUMO

Acinetobacter baumannii and Pseudomonas aeruginosa are frequent multiresistant nosocomial pathogens that cause wound and pulmonary infections in hospitalized patients. As being increasingly resistant to most clinically available antibiotics, there is a constant need for exploration of new substances that could kill them or inhibit their growth, or alternatively inhibit some of their essential virulence factors. Chalcones are chemical compounds with well-documented antimicrobial potential. The aim of this study was to examine effectiveness of four newly-synthesized chalcones against the multiresistant clinical strains of A. baumannii and P. aeruginosa. Antibacterial activity of chalcones was investigated with broth-microdilution test and time-dependent killing assay. Synergistic effects of tested compounds with antibiotics (meropenem, amikacin and ciprofloxacin) were determined by checkerboard assay. The effects of chalcones on expression of virulence factors in P. aeruginosa (pyocyanin production, swimming and swarming motility) and A. baumannii (twitching and surface-associated motility), along with their biofilm production, were also examined. The obtained results indicate substantial antimicrobial activity of the tested chalcones (MICs = 100-175 µg/mL) and several synergistic interactions with antibiotics, as well as notable reduction in expression of all investigated virulence factors. These promising results may constitute a good basis for further research.


Assuntos
Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/efeitos dos fármacos , Anti-Infecciosos/farmacologia , Chalconas/farmacologia , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Fatores de Virulência/metabolismo , Amicacina/farmacologia , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Chalconas/química , Ciprofloxacino/farmacologia , Combinação de Medicamentos , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Sinergismo Farmacológico , Hospitais , Humanos , Meropeném/farmacologia , Testes de Sensibilidade Microbiana , Piocianina/metabolismo
20.
Int J Med Microbiol ; 309(3-4): 213-224, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31010630

RESUMO

Clinical isolates of Klebsiella pneumoniae are often resistant to beta-lactam antibiotics via the acquisition of extended spectrum beta lactamase (ESBL) enzymes paired with loss of one or both major outer membrane porins. It has been well established that loss of OmpK35 and/or OmpK36 correlates with increased minimum inhibitory concentrations of antibiotics that target the peptidoglycan. However, little is known concerning the downstream effects porin loss might have on other major virulence factors such as the polysaccharide capsule or LPS. Furthermore, it is unknown whether these cumulative changes impact pathogenesis. Therefore, the focus of this study was to identify alterations in production of the major virulence factors due to porin loss; and to investigate the effect these changes have on host pathogen interactions. Our data demonstrates that loss of a single porin is paired with reductions in capsule, increased LPS content, and up-regulated transcription of compensatory porin genes. In contrast, loss of both porins resulted in a significant increase in capsule production. Loss of OmpK35 alone or dual porin loss was further associated with reduced oxidative burst by macrophages and increased ability of the bacteria to survive phagocytic killing. These data indicate that porin loss is accompanied by a suite of changes in other virulence-associated factors. These cumulative changes act to nullify any negative fitness effect due to lack of the nonspecific porin proteins, allowing the bacteria to grow and survive phagocytic immune responses.


Assuntos
Klebsiella pneumoniae/fisiologia , Klebsiella pneumoniae/patogenicidade , Macrófagos/microbiologia , Porinas/deficiência , Fatores de Virulência/metabolismo , Animais , Cápsulas Bacterianas/metabolismo , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Interações Hospedeiro-Patógeno , Humanos , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Lipopolissacarídeos/metabolismo , Macrófagos/metabolismo , Camundongos , Viabilidade Microbiana , Porinas/genética , Células RAW 264.7 , Transcrição Genética , Fatores de Virulência/genética , beta-Lactamases/genética , beta-Lactamases/metabolismo
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