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1.
Microbiol Spectr ; 6(1)2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29327679

RESUMO

Conjugative plasmids are the main carriers of transmissible antibiotic resistance (AbR) genes. For that reason, strategies to control plasmid transmission have been proposed as potential solutions to prevent AbR dissemination. Natural mechanisms that bacteria employ as defense barriers against invading genomes, such as restriction-modification or CRISPR-Cas systems, could be exploited to control conjugation. Besides, conjugative plasmids themselves display mechanisms to minimize their associated burden or to compete with related or unrelated plasmids. Thus, FinOP systems, composed of FinO repressor protein and FinP antisense RNA, aid plasmids to regulate their own transfer; exclusion systems avoid conjugative transfer of related plasmids to the same recipient bacteria; and fertility inhibition systems block transmission of unrelated plasmids from the same donor cell. Artificial strategies have also been designed to control bacterial conjugation. For instance, intrabodies against R388 relaxase expressed in recipient cells inhibit plasmid R388 conjugative transfer; pIII protein of bacteriophage M13 inhibits plasmid F transmission by obstructing conjugative pili; and unsaturated fatty acids prevent transfer of clinically relevant plasmids in different hosts, promoting plasmid extinction in bacterial populations. Overall, a number of exogenous and endogenous factors have an effect on the sophisticated process of bacterial conjugation. This review puts them together in an effort to offer a wide picture and inform research to control plasmid transmission, focusing on Gram-negative bacteria.


Assuntos
Conjugação Genética/fisiologia , Farmacorresistência Bacteriana Múltipla/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Transferência Genética Horizontal/fisiologia , Plasmídeos/fisiologia , Antibacterianos/farmacologia , Anticorpos Monoclonais/imunologia , Proteínas de Bactérias/imunologia , Conjugação Genética/genética , Endodesoxirribonucleases/imunologia , Ácidos Graxos Insaturados/química , Pili Sexual/imunologia , Pili Sexual/fisiologia , Plasmídeos/genética
2.
Mol Microbiol ; 107(3): 298-311, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29194812

RESUMO

Archaea are ubiquitously present in nature and colonize environments with broadly varying growth conditions. Several surface appendages support their colonization of new habitats. A hallmark of archaea seems to be the high abundance of type IV pili (T4P). However, some unique non T4 filaments are present in a number of archaeal species. Archaeal surface structures can mediate different processes such as cellular surface adhesion, DNA exchange, motility and biofilm formation and represent an initial attachment site for infecting viruses. In addition to the functionally characterized archaeal T4P, archaeal genomes encode a large number of T4P components that might form yet undiscovered surface structures with novel functions. In this review, we summarize recent advancement in structural and functional characterizations of known archaeal surface structures and highlight the diverse processes in which they play a role.


Assuntos
Archaea/fisiologia , Fímbrias Bacterianas/metabolismo , Archaea/metabolismo , Aderência Bacteriana/fisiologia , Biofilmes , Fímbrias Bacterianas/fisiologia , Proteínas de Membrana/metabolismo , Pili Sexual/fisiologia
3.
PLoS One ; 12(10): e0186248, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29023575

RESUMO

Self-transmissible plasmids are classified into two types based on their sex pili: short and rigid pili, and long and flexible pili. The transferability of two plasmids with different types of sex pili, pBP136 and pCAR1, was compared in stirring liquid conditions with different cell density. The most probable number method to count transconjugants could detect differences in the transfer frequency with higher resolution in comparison with the conventional CFU counting method. Both plasmids showed higher transfer frequency in high stirring rates than static liquid conditions when the donor and recipient density was 106-107 CFU mL-1. The probability of donor-initiated plasmid transfer was investigated by a single-cell-level analysis using a cell sorter. The probability was >36-fold higher for pBP136 than for pCAR1; thus, the simulated transfer frequency of pBP136 was much higher than that of pCAR1 in stirring liquid conditions. Nevertheless, the transfer frequency of pCAR1 was as high as that of pBP136 when the donor and recipient cell density was 106 CFU mL-1. This fact indicates that the lower probability of the donor pCAR1 to initiate transfer could be overcome by its high tolerance to the shearing force between donor and recipient cells under higher stirring liquid conditions. Our findings can explain the different survival strategies of these two types of plasmids based on their preferences of transfer conditions.


Assuntos
Plasmídeos/genética , Conjugação Genética , Transferência Genética Horizontal , Pili Sexual/fisiologia , Pseudomonas putida/genética
4.
Microbiol Spectr ; 3(3)2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26185067

RESUMO

Many Gram-positive and Gram-negative bacteria can become naturally competent to take up extracellular DNA from the environment via a dedicated uptake apparatus. The genetic material that is acquired can (i) be used for nutrients, (ii) aid in genome repair, and (iii) promote horizontal gene transfer when incorporated onto the genome by homologous recombination, the process of "transformation." Recent studies have identified multiple environmental cues sufficient to induce natural transformation in Vibrio cholerae and several other Vibrio species. In V. cholerae, nutrient limitation activates the cAMP receptor protein regulator, quorum-sensing signals promote synthesis of HapR-controlled QstR, chitin stimulates production of TfoX, and low extracellular nucleosides allow CytR to serve as an additional positive regulator. The network of signaling systems that trigger expression of each of these required regulators is well described, but the mechanisms by which each in turn controls competence apparatus genes is poorly understood. Recent work has defined a minimal set of genes that encode apparatus components and begun to characterize the architecture of the machinery by fluorescence microscopy. While studies with a small set of V. cholerae reference isolates have identified regulatory and competence genes required for DNA uptake, future studies may identify additional genes and regulatory connections, as well as revealing how common natural competence is among diverse V. cholerae isolates and other Vibrio species.


Assuntos
Competência de Transformação por DNA/genética , DNA Bacteriano/genética , Transferência Genética Horizontal/genética , Vibrio cholerae/genética , Transporte Biológico/genética , Quitina/metabolismo , Proteína Receptora de AMP Cíclico/metabolismo , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Ativação Enzimática , Proteínas de Fímbrias/genética , Regulação Bacteriana da Expressão Gênica , Pili Sexual/genética , Percepção de Quorum/genética , Percepção de Quorum/fisiologia , Transdução de Sinais/genética , Vibrio cholerae/patogenicidade
5.
Mol Oral Microbiol ; 29(5): 185-93, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24899524

RESUMO

Porphyromonas gingivalis is one of the main etiological organisms in periodontal disease. On oral surfaces P. gingivalis is a component of multispecies biofilm communities and can modify the pathogenic potential of the community as a whole. Accumulation of P. gingivalis in communities is facilitated by interspecies binding and communication with the antecedent colonizer Streptococcus gordonii. In this study we screened a library of small molecules to identify structures that could serve as lead compounds for the development of inhibitors of P. gingivalis community development. Three small molecules were identified that effectively inhibited accumulation of P. gingivalis on a substratum of S. gordonii. The structures of the small molecules are derived from the marine alkaloids oroidin and bromoageliferin and contain a 2-aminoimidazole or 2-aminobenzimidazole moiety. The most active compounds reduced expression of mfa1 and fimA in P. gingivalis, genes encoding the minor and major fimbrial subunits, respectively. These fimbrial adhesins are necessary for P. gingivalis co-adhesion with S. gordonii. These results demonstrate the potential for a small molecular inhibitor-based approach to the prevention of diseases associated with P. gingivalis.


Assuntos
Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Porphyromonas gingivalis/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/efeitos dos fármacos , Benzimidazóis/farmacologia , Liases de Carbono-Enxofre/efeitos dos fármacos , Proteínas de Fímbrias/antagonistas & inibidores , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imidazóis/farmacologia , Interações Microbianas , Microscopia Confocal/métodos , Pili Sexual/efeitos dos fármacos , Porphyromonas gingivalis/fisiologia , Pirróis/farmacologia , Streptococcus gordonii/fisiologia
6.
PLoS One ; 9(5): e96419, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24797914

RESUMO

The PilE pilin subunit protein of the gonococcal Type IV pilus (Tfp) colonization factor undergoes multisite, covalent modification with the zwitterionic phospho-form modification phosphoethanolamine (PE). In a mutant lacking the pilin-like PilV protein however, PilE is modified with a mixture of PE and phosphocholine (PC). Moreover, intrastrain variation of PilE PC modification levels have been observed in backgrounds that constitutively express PptA (the protein phospho-form transferase A) required for both PE and PC modification. The molecular basis underlying phospho-form microheterogeneity in these instances remains poorly defined. Here, we examined the effects of mutations at numerous loci that disrupt or perturb Tfp assembly and observed that these mutants phenocopy the pilV mutant vis a vis phospho-form modification status. Thus, PC modification appears to be directly or indirectly responsive to the efficacy of pilin subunit interactions. Despite the complexity of contributing factors identified here, the data favor a model in which increased retention in the inner membrane may act as a key signal in altering phospho-form modification. These results also provide an alternative explanation for the variation in PilE PC levels observed previously and that has been assumed to be due to phase variation of pptA. Moreover, mass spectrometry revealed evidence for mono- and di-methylated forms of PE attached to PilE in mutants deficient in pilus assembly, directly implicating a methyltransferase-based pathway for PC synthesis in N. gonorrhoeae.


Assuntos
Proteínas de Fímbrias/metabolismo , Neisseria gonorrhoeae/metabolismo , Cromatografia Líquida , Eletroforese em Gel de Poliacrilamida , Etanolaminas/química , Etanolaminas/metabolismo , Proteínas de Fímbrias/química , Proteínas de Fímbrias/genética , Regulação Bacteriana da Expressão Gênica , Glicosilação , Immunoblotting , Espectrometria de Massas , Modelos Moleculares , Mutação de Sentido Incorreto , Fosforilcolina/química , Fosforilcolina/metabolismo , Pili Sexual/metabolismo , Processamento de Proteína Pós-Traducional
7.
J Periodontol ; 85(1): 150-9, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23646850

RESUMO

BACKGROUND: The microbiologic feature of aggressive periodontitis (AgP) in Chinese patients has not yet been determined. This study aims to investigate the prevalence of eight periodontal microorganisms and the distribution of the Porphyromonas gingivalis fimA genotype in a cohort of Chinese patients with AgP. METHODS: Saliva and pooled subgingival plaque samples were collected from 81 patients with AgP (25 with incisor-first molar type and 56 with generalized type [GAgP]) and 34 periodontally healthy controls. Eight periodontal microorganisms, including Aggregatibacter actinomycetemcomitans, P. gingivalis, Tannerella forsythia, Treponema denticola, Campylobacter rectus, Prevotella intermedia, Prevotella nigrescens, and Fusobacterium nucleatum were detected in these samples by the polymerase chain reaction (PCR). In addition, the distribution of fimA genotypes was assessed in P. gingivalis-positive individuals by PCR. RESULTS: The prevalence of P. gingivalis, T. forsythia, T. denticola, C. rectus, P. intermedia, F. nucleatum, and A. actinomycetemcomitans in patients with AgP was significantly higher than that in healthy controls. The prevalence of A. actinomycetemcomitans in patients with GAgP was relatively low (30.4%) compared with other pathogens. Results of logistic regression analysis showed that younger patients were more likely to harbor A. actinomycetemcomitans (odds ratio = 2.85). Type II was the most prevalent fimA genotype of P. gingivalis in patients with AgP. CONCLUSIONS: P. gingivalis, T. forsythia, T. denticola, C. rectus, P. intermedia, and F. nucleatum were the predominant periodontal pathogens of patients with GAgP in China. Type II of fimA was the most prevalent genotype of P. gingivalis in patients with AgP. The prevalence of A. actinomycetemcomitans in patients with GAgP was relatively low.


Assuntos
Periodontite Agressiva/microbiologia , Bactérias/classificação , Proteínas de Fímbrias/genética , Pili Sexual/genética , Porphyromonas gingivalis/classificação , Adulto , Fatores Etários , Aggregatibacter actinomycetemcomitans/isolamento & purificação , Periodontite Agressiva/classificação , Carga Bacteriana , Bacteroides/isolamento & purificação , Campylobacter rectus/isolamento & purificação , Estudos de Coortes , Placa Dentária/microbiologia , Feminino , Fusobacterium nucleatum/isolamento & purificação , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Prevotella intermedia/isolamento & purificação , Prevotella nigrescens/isolamento & purificação , Saliva/microbiologia , Treponema denticola/isolamento & purificação , Adulto Jovem
8.
J Periodontol ; 85(6): 837-44, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24147843

RESUMO

BACKGROUND: Cigarette smokers are more susceptible to periodontal diseases and are more likely to be infected with Porphyromonas gingivalis than non-smokers. Furthermore, smoking is known to alter the expression of P. gingivalis surface components and compromise immunoglobulin (Ig)G generation. The aim of this study is to evaluate whether the overall IgG response to P. gingivalis is suppressed in smokers in vivo and whether previously established in vitro tobacco-induced phenotypic P. gingivalis changes would be reflected in vivo. METHODS: The authors examined the humoral response to several P. gingivalis strains as well as specific tobacco-regulated outer membrane proteins (FimA and RagB) by enzyme-linked immunosorbent assay in biochemically validated (salivary cotinine) smokers and non-smokers with chronic periodontitis (CP: n = 13) or aggressive periodontitis (AgP: n = 20). The local and systemic presence of P. gingivalis DNA was also monitored by polymerase chain reaction. RESULTS: Smoking was associated with decreased total IgG responses against clinical (10512, 5607, and 10208C; all P <0.05) but not laboratory (ATCC 33277, W83) P. gingivalis strains. Smoking did not influence IgG produced against specific cell-surface proteins, although a non-significant pattern toward increased total FimA-specific IgG in patients with CP, but not AgP, was observed. Seropositive smokers were more likely to be infected orally and systemically with P. gingivalis (P <0.001), as determined by 16S RNA analysis. CONCLUSION: Smoking alters the humoral response against P. gingivalis and may increase P. gingivalis infectivity, strengthening the evidence that mechanisms of periodontal disease progression in smokers may differ from those of non-smokers with the same disease classification.


Assuntos
Periodontite Agressiva/microbiologia , Antígenos de Bactérias/imunologia , Periodontite Crônica/microbiologia , Porphyromonas gingivalis/imunologia , Fumar/imunologia , Adulto , Periodontite Agressiva/imunologia , Anticorpos Antibacterianos/imunologia , Proteínas de Bactérias/imunologia , Infecções por Bacteroidaceae/imunologia , Infecções por Bacteroidaceae/microbiologia , Periodontite Crônica/imunologia , Cotinina/análise , DNA Bacteriano/análise , Índice de Placa Dentária , Feminino , Proteínas de Fímbrias/imunologia , Humanos , Imunoglobulina G/imunologia , Masculino , Pessoa de Meia-Idade , Índice Periodontal , Fenótipo , Pili Sexual/imunologia , Porphyromonas gingivalis/genética , Porphyromonas gingivalis/patogenicidade , Saliva/química , Tabaco
9.
J Investig Clin Dent ; 5(3): 201-7, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23447375

RESUMO

AIM: The objective of the present study was to detect the presence of Porphyromonas gingivalis (fimA), Aggregatibacter actinomycetemcomitans, and red complex in the coronary plaque of patients with coronary artery disease. METHODS: The study population consisted of 51 patients with chronic periodontitis undergoing coronary artery bypass grafting. DNA was extracted from subgingival and coronary atherosclerotic plaque samples. Polymerase chain reaction was used to amplify the part of 16S rRNA gene to detect the presence of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis (fimA), Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola. RESULTS: Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Porphyromonas gingivalis, Porphyromonas gingivalis (fimA), and Treponema denticola were detected in 0%, 31.4%, 45.1%, 39.2%, and 51% of the atherosclerotic plaque samples, respectively. In both subgingival and coronary atherosclerotic plaque samples, Tannerella forsythia was detected in 19.6%, Porphyromonas gingivalis in 39.2%, Porphyromonas gingivalis (fimA) in 33.3%, and Treponema denticola in 35.3% of the samples. CONCLUSION: The study confirmed the detection of red complex bacteria in coronary plaque samples. However Aggregatibacter actinomycetemcomitans could not be detected in these samples.


Assuntos
Aggregatibacter actinomycetemcomitans/genética , Doença da Artéria Coronariana/microbiologia , Proteínas de Fímbrias/genética , Pili Sexual/genética , Placa Aterosclerótica/microbiologia , Porphyromonas gingivalis/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Aggregatibacter actinomycetemcomitans/classificação , Bacteroides/classificação , Bacteroides/genética , Periodontite Crônica/complicações , Periodontite Crônica/microbiologia , Ponte de Artéria Coronária , Doença da Artéria Coronariana/cirurgia , DNA Bacteriano/análise , Placa Dentária/microbiologia , Índice de Placa Dentária , Feminino , Proteínas de Fímbrias/classificação , Humanos , Masculino , Pessoa de Meia-Idade , Pili Sexual/classificação , Placa Aterosclerótica/cirurgia , Reação em Cadeia da Polimerase , Porphyromonas gingivalis/classificação , RNA Bacteriano/análise , RNA Ribossômico 16S/análise , Treponema denticola/classificação , Treponema denticola/genética
10.
Immunol Res ; 57(1-3): 229-36, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24203442

RESUMO

Enterotoxigenic Escherichia coli is frequently associated with travelers' diarrhea and is a leading cause of infant and childhood mortality in developing countries. Disease is dependent upon the orchestrated expression of enterotoxins, flexible adhesive pili, and other virulence factors. Both the heat-labile (LT) and heat-stable (ST-H) enterotoxins are regulated at the level of transcription by cAMP-receptor protein which represses the expression of LT while activating expression of ST-H. The expression of many different serotypes of adhesive pili is regulated by Rns, a member of the AraC family that represents a subgroup of conserved virulence regulators from several enteric pathogens. These Rns-like regulators recognize similar DNA binding sites, and a compiled sequence logo suggests they may bind DNA through both major and minor groove interactions. These regulators are also tempting targets for novel therapeutics because they play pivotal roles during infection. To that end, high-throughput screens have begun to identify compounds that inhibit the activity of these regulators, predominately by interfering with DNA binding.


Assuntos
Escherichia coli Enterotoxigênica/genética , Escherichia coli Enterotoxigênica/patogenicidade , Regulon/genética , Animais , Aderência Bacteriana/genética , Sítios de Ligação , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Diarreia/microbiologia , Escherichia coli Enterotoxigênica/metabolismo , Enterotoxinas/genética , Enterotoxinas/metabolismo , Humanos , Pili Sexual/genética , Pili Sexual/metabolismo , Domínios e Motivos de Interação entre Proteínas , Transativadores/química , Transativadores/genética , Transativadores/metabolismo , Virulência
11.
Mol Oral Microbiol ; 28(5): 392-403, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23809984

RESUMO

The periodontal pathogen Porphyromonas gingivalis generally expresses two distinct fimbriae, FimA and Mfa1, which play a role in biofilm formation. The fimA gene that encodes FimA fimbrilin is polymorphic, and polymerase chain reaction analysis has identified six genotypes called types I-V and Ib. We found recently that fimbriae exhibit antigenic heterogeneity among the genotypes. In the present study, we analysed the fimA DNA sequences of 84 strains of P. gingivalis and characterized the antigenicity of FimA fimbriae. Strains analysed here comprised 10, 16, 29, 13, 10 and 6 strains of types I, Ib, II, III, IV and V, respectively. DNA sequencing revealed that type Ib does not represent a single cluster and that type II sequences are remarkably diverse. In contrast, the fimA sequences of the other types were relatively homogeneous. Antigenicity was investigated using antisera elicited by pure FimA fimbriae of types I-V. Antigenicity correlated generally with the respective genotype. Type Ib strains were recognized by type I antisera. However, some strains showed cross-reactivity, especially, many type II strains reacted with type III antisera. The levels of fimbrial expression were highly variable, and expression was positively correlated with ability of biofilm formation on a saliva-coated plate. Further, two strains without FimA and Mfa1 fimbriae expressed fimbrial structures, suggesting that the strains produce other types of fimbriae.


Assuntos
Antígenos de Bactérias/genética , Proteínas de Fímbrias/genética , Pili Sexual/genética , Porphyromonas gingivalis/genética , Variação Antigênica/genética , Antígenos de Bactérias/classificação , Antígenos de Bactérias/imunologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Biofilmes , Reações Cruzadas/imunologia , DNA Bacteriano/genética , Película Dentária/microbiologia , Proteínas de Fímbrias/classificação , Proteínas de Fímbrias/imunologia , Genótipo , Humanos , Fases de Leitura Aberta/genética , Pili Sexual/imunologia , Porphyromonas gingivalis/imunologia , Saliva/microbiologia , Análise de Sequência de DNA
12.
J Clin Pediatr Dent ; 37(3): 289-95, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23855174

RESUMO

UNLABELLED: The aim of this study was to characterize the main periodontal bacterial species in Down syndrome (DS) patients with and without periodontitis. METHOD: This cross-sectional study involved 75 DS patients, 45 with and 30 without periodontitis. Informed consent, health and dental questionnaires and periodontitis diagnosis were performed PCR and LAMP assays were performed on subgingival dental plaque sample. RESULTS: Tannerella forsythia was the most frequent bacteria detected in the group with and without periodontitis (95.5 and 63.3%) followed by Treponema denticola (88.8 and 50%) and Porphyromonas gingivalis (53.3 and 25% respectively). There were statistical differences between groups (p < 0.05). Pg fimA type I was the most frequent Porphyromonas gingivalis genotype. Two different sets of primers (Aa-F/Aa-R and ltx3/ltx4) were used to detect Aggregatibacter actinomycetemcomitans and different frequencies were obtained, (68% and 14.6% respectively), they had a weak correlation (Cohen Kappa = 0.16). After sequencing of PCR products, ltx3/ltx4 showed more specificity. JP2 clone of A. actinomycetemcomitans was not detected in any sample. CONCLUSIONS: The composition of oral biofilm is fundamental for the development of periodontal disease independently of immunological alterations associated with DS. The frequency of detection of A. actinomycetemcomitans reported in the literature has a wide range, because the primers and probes applied


Assuntos
Biofilmes/classificação , Placa Dentária/microbiologia , Síndrome de Down/microbiologia , Periodontite/microbiologia , Aggregatibacter actinomycetemcomitans/classificação , Aggregatibacter actinomycetemcomitans/genética , Aggregatibacter actinomycetemcomitans/isolamento & purificação , Toxinas Bacterianas/genética , Bacteroides/isolamento & purificação , Estudos Transversais , Primers do DNA , DNA Bacteriano/análise , Exotoxinas/genética , Feminino , Proteínas de Fímbrias/análise , Genótipo , Humanos , Masculino , Consórcios Microbianos , Perda da Inserção Periodontal/classificação , Perda da Inserção Periodontal/microbiologia , Bolsa Periodontal/classificação , Bolsa Periodontal/microbiologia , Periodontite/classificação , Periodonto/microbiologia , Pili Sexual/genética , Porphyromonas gingivalis/genética , Porphyromonas gingivalis/isolamento & purificação , Perda de Dente/classificação , Treponema denticola/isolamento & purificação , Adulto Jovem
13.
Plasmid ; 70(2): 254-62, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23721858

RESUMO

Pseudomonas sp. GLE121 (a psychrophilic Antarctic strain) carries three plasmids: pGLE121P1 (6899 bp), pGLE121P2 (8330 bp) and pGLE121P3 (39,583 bp). Plasmids pGLE121P1 and pGLE121P2 show significant sequence similarity to members of the IncP-9 and IncP-7 incompatibility groups, respectively, while the largest replicon, pGLE121P3, is highly related to plasmid pNCPPB880-40 of Pseudomonas syringae pathovar tomato NCPPB880. All three plasmids have a narrow host range, limited to members of the genus Pseudomonas. Plasmid pGLE121P3 encodes a conjugal transfer system, while pGLE121P1 carries only a putative MOB module, conserved in many mobilizable plasmids. Plasmid pGLE121P3 contains an additional load of genetic information, including a pair of genes with homology to the rulAB operon, responsible for ultraviolet radiation (UVR) tolerance. Given the increasing UV exposure in Antarctic regions, the expression of these genes is likely to be an important adaptive response.


Assuntos
Camada de Gelo/microbiologia , Plasmídeos/genética , Pseudomonas/genética , Regiões Antárticas , Sequência de Bases , Biologia Computacional , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Transferência Genética Horizontal/genética , Dados de Sequência Molecular , Pili Sexual/genética , Análise de Sequência de DNA
14.
PLoS One ; 8(4): e62735, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23646138

RESUMO

The Pseudomonas aeruginosa fimbrial structures encoded by the cup gene clusters (cupB and cupC) contribute to its attachment to abiotic surfaces and biofilm formation. The P. aeruginosa pvcABCD gene cluster encodes enzymes that synthesize a novel isonitrile functionalized cumarin, paerucumarin. Paerucumarin has already been characterized chemically, but this is the first report elucidating its role in bacterial biology. We examined the relationship between the pvc operon and the cup gene clusters in the P. aeruginosa strain MPAO1. Mutations within the pvc genes compromised biofilm development and significantly reduced the expression of cupB1-6 and cupC1-3, as well as different genes of the cupB/cupC two-component regulatory systems, roc1/roc2. Adjacent to pvc is the transcriptional regulator ptxR. A ptxR mutation in MPAO1 significantly reduced the expression of the pvc genes, the cupB/cupC genes, and the roc1/roc2 genes. Overexpression of the intact chromosomally-encoded pvc operon by a ptxR plasmid significantly enhanced cupB2, cupC2, rocS1, and rocS2 expression and biofilm development. Exogenously added paerucumarin significantly increased the expression of cupB2, cupC2, rocS1 and rocS2 in the pvcA mutant. Our results suggest that pvc influences P. aeruginosa biofilm development through the cup gene clusters in a pathway that involves paerucumarin, PtxR, and different cup regulators.


Assuntos
Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Chaperonas Moleculares/genética , Óperon , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismo , Transdução de Sinais , Proteínas de Bactérias/metabolismo , Biofilmes , Flagelos/genética , Flagelos/metabolismo , Modelos Biológicos , Chaperonas Moleculares/metabolismo , Família Multigênica , Mutação , Pili Sexual/genética , Pili Sexual/metabolismo , Ligação Proteica , Pseudomonas aeruginosa/crescimento & desenvolvimento
15.
J Biol Chem ; 288(18): 12979-91, 2013 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-23486474

RESUMO

Infection of Escherichia coli by the filamentous phage fd starts with the binding of the N2 domain of the phage gene-3-protein to an F pilus. This interaction triggers partial unfolding of the gene-3-protein, cis → trans isomerization at Pro-213, and domain disassembly, thereby exposing its binding site for the ultimate receptor TolA. The trans-proline sets a molecular timer to maintain the binding-active state long enough for the phage to interact with TolA. We elucidated the changes in structure and local stability that lead to partial unfolding and thus to the activation of the gene-3-protein for phage infection. Protein folding and TolA binding experiments were combined with real-time NMR spectroscopy, amide hydrogen exchange measurements, and phage infectivity assays. In combination, the results provide a molecular picture of how a local unfolding reaction couples with prolyl isomerization not only to generate the activated state of a protein but also to maintain it for an extended time.


Assuntos
Bacteriófago M13/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/virologia , Pili Sexual/metabolismo , Prolina/metabolismo , Desdobramento de Proteína , Proteínas Virais/metabolismo , Bacteriófago M13/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Ressonância Magnética Nuclear Biomolecular , Pili Sexual/genética , Prolina/genética , Proteínas Virais/genética
16.
IEEE Trans Nanobioscience ; 12(1): 47-59, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23392386

RESUMO

Molecular communication is a new paradigm for nanomachines to exchange information, by utilizing biological mechanism and/or components to transfer information (e.g., molecular diffusion, neuronal networks, molecular motors). One possible approach for molecular communication is through the use of bacteria, which can act as carriers for DNA-based information, i.e., plasmids. This paper analyzes multi-hop molecular nanonetworks that utilize bacteria as a carrier. The proposed approach combines different properties of bacteria to enable multi-hop transmission, such as conjugation and chemotaxis-based motility. Various analyses have been performed, including the correlation between the success rate of plasmid delivery to the destination node, and the role of conjugation in enabling this; as well as analyses on the impact of large topology shapes (e.g., Grid, Random, and Scale-free) on the success rate of plasmid delivery for multiple source-destination nanonetworks. A further solution proposed in this paper is the application of antibiotics to act as filters on illegitimate messages that could be delivered by the bacteria. Our evaluation, which has been conducted through a series of simulations, has shown that numerous bacteria properties fit to properties required for communication networking (e.g., packet filtering, routing, addressing).


Assuntos
Bactérias/genética , Computadores Moleculares , Conjugação Genética , Modelos Biológicos , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Comunicação Celular , Fatores Quimiotáticos/farmacologia , Comunicação , Simulação por Computador , Entropia , Interações Microbianas , Modelos Moleculares , Nanotecnologia , Pili Sexual , Plasmídeos/química , Plasmídeos/metabolismo
17.
Microbiol Mol Biol Rev ; 76(4): 740-72, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23204365

RESUMO

Type IV pili (T4P) are multifunctional protein fibers produced on the surfaces of a wide variety of bacteria and archaea. The major subunit of T4P is the type IV pilin, and structurally related proteins are found as components of the type II secretion (T2S) system, where they are called pseudopilins; of DNA uptake/competence systems in both Gram-negative and Gram-positive species; and of flagella, pili, and sugar-binding systems in the archaea. This broad distribution of a single protein family implies both a common evolutionary origin and a highly adaptable functional plan. The type IV pilin is a remarkably versatile architectural module that has been adopted widely for a variety of functions, including motility, attachment to chemically diverse surfaces, electrical conductance, acquisition of DNA, and secretion of a broad range of structurally distinct protein substrates. In this review, we consider recent advances in this research area, from structural revelations to insights into diversity, posttranslational modifications, regulation, and function.


Assuntos
Fenômenos Fisiológicos Bacterianos , Proteínas de Fímbrias , Fímbrias Bacterianas/metabolismo , Interações Hospedeiro-Patógeno , Subunidades Proteicas , Biofilmes/crescimento & desenvolvimento , Conjugação Genética , Proteínas de Fímbrias/química , Proteínas de Fímbrias/genética , Proteínas de Fímbrias/metabolismo , Variação Genética , Pili Sexual , Estrutura Secundária de Proteína , Subunidades Proteicas/química , Subunidades Proteicas/metabolismo , Transdução de Sinais , Transcrição Genética
18.
Mol Oral Microbiol ; 26(6): 388-95, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22053966

RESUMO

Porphyromonas gingivalis is a primary pathogen involved in the initiation and progression of adult chronic periodontitis. Its colonization on oral surfaces is a necessary first step leading to infection. FimA, a subunit protein of major (long) fimbriae, is a well-known virulence factor. Based on its nucleotide sequence, FimA is classified into several genotypes. We compared here the transcriptional levels of the fimA gene in several P. gingivalis strains using real-time polymerase chain reaction analysis, fimbrial display on the P. gingivalis surface using transmission electronic microscopy, and the adherence competencies of P. gingivalis strains carrying different types of FimAs towards saliva and Streptococcus gordonii surfaces using mutagenesis analysis. We demonstrated differential expression of each fimA gene in these P. gingivalis strains. A correlation of the transcription level of fimA and binding activity of P. gingivalis was revealed. We show that P. gingivalis strains with genotype I and II of FimA are efficient in interaction with saliva or S. gordonii. This work highlights the important role of FimA type I and II in P. gingivalis attachment to oral surfaces.


Assuntos
Aderência Bacteriana/genética , Proteínas de Fímbrias/genética , Pili Sexual/genética , Porphyromonas gingivalis/genética , Adulto , Carga Bacteriana , Película Dentária/microbiologia , Feminino , Genótipo , Humanos , Microscopia Eletrônica de Transmissão , Mutagênese/genética , Mutagênese Insercional/genética , Porphyromonas gingivalis/fisiologia , Reação em Cadeia da Polimerase em Tempo Real , Streptococcus gordonii/fisiologia , Transcrição Genética/genética
19.
J Biol Chem ; 286(51): 43601-10, 2011 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-22006923

RESUMO

The type IV secretion system (T4SS) encoded within the gonococcal genetic island (GGI) of Neisseria gonorrhoeae has homology to the T4SS encoded on the F plasmid. The GGI encodes the putative pilin protein TraA and a serine protease TrbI, which is homologous to the TraF protein of the RP4 plasmid involved in circularization of pilin subunits of P-type pili. TraA was processed to a 68-amino acid long circular peptide by leader peptidase and TrbI. Processing occurred after co-translational membrane insertion and was independent of other proteins. Circularization occurred after removal of three C-terminal amino acids. Mutational analysis of TraA revealed limited flexibility at the cleavage and joining sites. Mutagenesis of TrbI showed that the conserved Lys-93 and Asp-155 are essential, whereas mutagenesis of Ser-52, the putative catalytic serine did not influence circularization. Further mutagenesis of other serine residues did not identify a catalytic serine, indicating that TrbI either contains redundant catalytic serine residues or does not function via a serine-lysine dyad mechanism. In vitro studies revealed that circularization occurs via a covalent intermediate between the C terminus of TraA and TrbI. The intermediate is processed to the circular form after cleavage of the N-terminal signal sequence. This is the first demonstration of a covalent intermediate in the circularization mechanism of conjugative pili.


Assuntos
Proteínas de Fímbrias/química , Neisseria gonorrhoeae/metabolismo , Análise Mutacional de DNA , Escherichia coli/metabolismo , Proteínas de Escherichia coli/química , Espectrometria de Massas/métodos , Proteínas de Membrana/química , Modelos Genéticos , Mutação , Neisseria gonorrhoeae/genética , Pili Sexual/química , Plasmídeos/metabolismo , Estrutura Terciária de Proteína , Transporte Proteico , Serina Endopeptidases/química
20.
PLoS One ; 6(5): e19991, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21637841

RESUMO

Conjugation is the main mode of horizontal gene transfer that spreads antibiotic resistance among bacteria. Strategies for inhibiting conjugation may be useful for preserving the effectiveness of antibiotics and preventing the emergence of bacterial strains with multiple resistances. Filamentous bacteriophages were first observed to inhibit conjugation several decades ago. Here we investigate the mechanism of inhibition and find that the primary effect on conjugation is occlusion of the conjugative pilus by phage particles. This interaction is mediated primarily by phage coat protein g3p, and exogenous addition of the soluble fragment of g3p inhibited conjugation at low nanomolar concentrations. Our data are quantitatively consistent with a simple model in which association between the pili and phage particles or g3p prevents transmission of an F plasmid encoding tetracycline resistance. We also observe a decrease in the donor ability of infected cells, which is quantitatively consistent with a reduction in pili elaboration. Since many antibiotic-resistance factors confer susceptibility to phage infection through expression of conjugative pili (the receptor for filamentous phage), these results suggest that phage may be a source of soluble proteins that slow the spread of antibiotic resistance genes.


Assuntos
Bacteriófago M13/metabolismo , Conjugação Genética , Modelos Biológicos , Proteínas Virais/metabolismo , Bacteriófago M13/genética , Bacteriófago M13/fisiologia , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/virologia , Fator F/metabolismo , Genes Virais/genética , Pili Sexual/metabolismo , Fatores de Tempo , Replicação Viral
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