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1.
Medicina (Kaunas) ; 60(3)2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38541225

RESUMO

Background and Objectives: Workplace burnout syndrome is often as sociated with particular aspects of certain job positions, especially those that entail working with people with special needs. The burnout syndrome in healthcare jobs is a serious problem that has grown into an epidemic among healthcare workers and associates. The aim of this research is to assess the presence of stress and burnout syndrome at work with healthcare workers, expert workers, professional associates, and associates in social service institutions in Belgrade. Materials and Methods: This research was conducted in the form of a cross-sectional study of a representative sample in social institutions in Belgrade. It was conducted from March to the end of June of 2023. The sample of the study had 491 participants. The questionnaires used were a structured instrument with social-demographic and social-economic characteristics, workplace characteristics, lifestyle characteristics, and the following questionnaires: DASS-21, Copenhagen, Brief Resilience Scale, and Brief Resilient Coping Scale. Results: The end results indicate the following to be significant risk factors for the occurrence of workplace burnout syndrome: overtime (OR = 2.62; CI = 1.50-4.56), BRS average score (OR = 0.28; CI = 0.17-0.44), DASS21 D heightened depression (OR = 2.09; CI = 1.1-4.04), DASS21 A heightened anxiety (OR = 2.38; CI = 1.34-4.21), and DASS21 S heightened stress (OR = 2.08; CI = 1.11-3.89). The only protective risk factor that stood out was the self-assessment of health levels (OR = 0.60; CI = 0.42-0.85). Conclusion: Overtime is a significant factor associated with workplace burnout. Apart from it, other significant factors associated with workplace burnout were heightened depression, anxiety, and stress levels.


Assuntos
Esgotamento Profissional , Pessoal de Saúde , Humanos , Estudos Transversais , Esgotamento Profissional/epidemiologia , Esgotamento Profissional/etiologia , Local de Trabalho , Inquéritos e Questionários , Serviço Social
2.
Chembiochem ; 23(10): e202100698, 2022 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-35298064

RESUMO

Termites live in a dynamic environment where colony health is strongly influenced by surrounding microbes. However, little is known about the mycobiomes of lower termites and their nests, and how these change in response to disease. Here we compared the individual and nest mycobiomes of a healthy subterranean termite colony (Coptotermes testaceus) to one infected and ultimately eradicated by a fungal pathogen. We identified Trichoderma species in the materials of both nests, but they were also abundant in the infected termites. Methanolic extracts of Trichoderma sp. FHG000531, isolated from the infected nest, were screened for secondary metabolites by UHPLC-HR MS/MS-guided molecular networking. We identified many bioactive compounds with potential roles in the eradication of the infected colony, as well as a cluster of six unknown peptides. The novel peptide FE011 was isolated and characterized by NMR spectroscopy. The function of this novel peptide family as well as the role of Trichoderma species in dying termite colonies therefore requires further investigation.


Assuntos
Isópteros , Micobioma , Trichoderma , Animais , Isópteros/microbiologia , Espectrometria de Massas em Tandem
3.
Environ Monit Assess ; 187(9): 599, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26314345

RESUMO

Despite the number of studies on antibiotic-resistant enterococci from Serbian clinical settings, there are no data about environmental contamination with these bacteria. Thus, this study investigated the prevalence of antibiotic-resistant enterococci in Belgrade, Serbia. Enterococcus species collected from ten surface water sites, including a lake, two major river systems, and springs, were tested. Among enterococci, we found single (21.7 %), double (17.4 %), and multiple antibiotic resistance patterns (56.3 %). Vancomycin-resistant strains were not found, indicating that their abundance in Belgrade is tightly linked to clinical settings. The multiple drug-resistant strains Enterococcus faecalis, Enterococcus faecium, and Enterococcus mundtii were frequently detected in the lake during the swimming season and in the rivers near industrial zones. We confirmed the presence of ermB, ermC, ant(6)-Ia, tetM, and tetL and mutations in gyrA genes. The phylogenetic analysis of 16S rRNA gene of E. faecium isolates that harbor esp gene classified them into two groups based on high-bootstraps scores in the tree analysis. Pulsed-field gel electrophoresis analysis of antibiotic-resistant enterococci revealed genomic similarity ranging from 75 to 100 %. This study indicates the importance of anthropogenic impact to the spread of antibiotic-resistant enterococci in environmental waters of Belgrade, Serbia.


Assuntos
Cidades , Farmacorresistência Bacteriana Múltipla/genética , Enterococcus/genética , Monitoramento Ambiental/estatística & dados numéricos , Lagos/microbiologia , Rios/microbiologia , Sequência de Bases , Eletroforese em Gel de Campo Pulsado , Monitoramento Ambiental/métodos , Genes Bacterianos/genética , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Mutação/genética , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Sérvia
4.
Food Microbiol ; 39: 27-38, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24387849

RESUMO

The aim of this study was to investigate the composition of lactic acid bacteria (LAB) in autochthonous young cheeses, sweet creams and sweet kajmaks produced in the Vlasic mountain region of central Bosnia and Herzegovina near the town of Travnik over a four season period. These three products were made from cow's milk by a traditional method without the addition of a starter culture. Preliminary characterization with phenotype-based assays and identification using rep-PCR with a (GTG)5 primer and 16S rDNA sequence analysis were undertaken for 460 LAB isolates obtained from all the examined samples. Fifteen species were identified as follows: Lactococcus lactis, Lactococcus raffinolactis, Lactococcus garviae, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus helveticus, Enterococcus faecium, Enterococcus durans, Enterococcus faecalis, Enterococcus italicus, Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides, Leuconostoc lactis, Streptococcus thermophilus and Streptococcus mitis. A wide genotypic and phenotypic heterogeneity of the species was observed, particularly within the Lc. lactis strains. In all of the tested dairy products across four seasons, a significantly positive correlation (r = 0.690) between the presence of lactococci and enterococci and a negative correlation (r = 0.722) between the presence of lactococci and leuconostocs were recorded. Forty-five percent of the lactobacilli and 54.4% of the lactococci exhibited proteolytic activity, whereas 18.7% of the total LAB isolates exhibited antimicrobial activity.


Assuntos
Queijo/microbiologia , Laticínios/microbiologia , Lactobacillaceae/isolamento & purificação , Animais , Biodiversidade , Bovinos , Ácido Láctico/metabolismo , Lactobacillaceae/classificação , Lactobacillaceae/genética , Lactobacillaceae/metabolismo , Leite/microbiologia , Dados de Sequência Molecular , Filogenia , Estações do Ano , Sérvia
5.
Case Rep Oncol Med ; 2024: 6699698, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38765733

RESUMO

Li-Fraumeni syndrome (LFS) is a cancer predisposition syndrome associated with a high, lifetime risk of a broad spectrum of cancers caused by pathogenic germline TP53 mutations. Numerous different germline TP53 mutations have been associated with LFS, which has an exceptionally diverse clinical spectrum in terms of tumor type and age of onset. Our patient has developed six asynchronous tumors to date: a phyllode tumor of the breast, a pheochromocytoma, a rosette-forming glioneuronal tumor (RGNT), an adrenocortical carcinoma (ACC), a ductal carcinoma of the breast, and a thymoma. The occurrence of such a number of rare tumors is sporadic even among in the population of patients living with cancer predisposition syndromes. In this instance, the omission of pretest genetic counseling and thorough family tree analysis prior to selecting the test led to the oversight of an underlying TP53 likely pathogenic mutation (classified as Class 4). This emphasizes the necessity for such counseling to prevent overlooking crucial genetic information. Neglecting this step could have had profound implications on the patient's treatment, particularly considering the early onset and occurrence of multiple tumors, which typically raise suspicion of a hereditary component. The implications for family members must be considered.

6.
Microbiol Resour Announc ; 13(6): e0129723, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38988209

RESUMO

Galbibacter sp. PAP.153 was isolated from a marine sponge. Here, we report its 4.12 Mbp draft genome sequence and rate its specialized metabolite production capacity with specific focus on the chemotaxonomic marker flexirubin.

7.
Microbiol Resour Announc ; 13(4): e0118523, 2024 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-38411067

RESUMO

The genomes of 21 Pedobacter strains isolated from the European salamander Salamandra salamandra and different Madagascan frog species were sequenced using Illumina sequencing. Here, we report their draft genome sequences (~4.7-7.2 Mbp in size) to allow comparative genomics and taxonomic assignment of these strains.

8.
Microbiol Resour Announc ; 12(4): e0126822, 2023 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-36943053

RESUMO

Sinomicrobium sp. strain PAP.21 (EXT111902) was isolated from the coast of Cenderawasih Bay National Park in West Papua, Indonesia. Its genome was assembled into 151 contigs with a total size of 5.439 Mbp, enabling the prediction of its specialized metabolite production capacity.

9.
Microbiol Resour Announc ; 12(4): e0126422, 2023 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-36927116

RESUMO

Algoriphagus sp. strain PAP.12 (EXT111900) and Roseivirga sp. strain PAP.19 (EXT111901) were isolated from marine samples. Here, we report their draft genome sequences, 5.032 Mbp and 4.583 Mbp in size, respectively, and rate their specialized metabolite production capacity. Taxonomic ranks established by genome-based analysis indicate that Algoriphagus sp. strain PAP.12 represents a candidate new species.

10.
Microbiol Spectr ; 11(1): e0443722, 2023 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-36692293

RESUMO

The emergence and spread of antimicrobial resistance (AMR) in Gram-negative pathogens, such as carbapenem-resistant Pseudomonas aeruginosa, pose an increasing threat to health care. Patients with immunodeficiencies or chronic pulmonary disease, like cystic fibrosis (CF), are particularly vulnerable to Pseudomonas infections and depend heavily on antibiotic therapy. To broaden limited treatment options, this study evaluated the potency of the recently licensed drugs ceftazidime-avibactam (CZA), ceftolozane-tazobactam (C/T), and cefiderocol (FDC) as well as two novel preclinical antibiotics, darobactins B (DAR B) and B9 (DAR B9), against clinical P. aeruginosa isolates derived from respiratory samples of CF patients. We observed high levels of resistance to all three newly licensed drugs, with cefiderocol exhibiting the best activity. From the 66 investigated P. aeruginosa isolates, a total of 53% were resistant to CZA, 49% to C/T, and 30% to FDC. Strikingly, 52 of the evaluated isolates were obtained from CF patients prior to market introduction of the drugs. Thus, our results suggest that resistance to CZA, C/T, and FDC may be due to preexisting resistance mechanisms. On the other hand, our two novel preclinical compounds performed better than (CZA and C/T) or close to (FDC) the licensed drugs-most likely due to the novel mode of action. Thus, our results highlight the necessity of global consistency in the area of antibiotic stewardship to prevent AMR from further impairing the potency of antibiotics in clinical practice. Ultimately, this study demonstrates the urgency to support the development of novel antimicrobials, preferably with a new mode of action such as darobactins B and B9, two very promising antimicrobial compounds for the treatment of critically ill patients suffering from multidrug-resistant Gram-negative (MRGN) infections. IMPORTANCE Antimicrobial resistance (AMR) represents an ever increasing threat to the health care system. Even recently licensed drugs are often not efficient for the treatment of infections caused by Gram-negative bacteria, like Pseudomonas aeruginosa, a causative agent of lung infections. To address this unmet medical need, innovative antibiotics, which possess a new mode of action, need to be developed. Here, the antibiogram of clinical isolates derived from cystic fibrosis patients was generated and new bicyclic heptapeptides, which inhibit the outer membrane protein BamA, exhibited strong activity, also against multidrug-resistant isolates.


Assuntos
Fibrose Cística , Infecções por Pseudomonas , Humanos , Adolescente , Criança , Pseudomonas aeruginosa , Fibrose Cística/complicações , Cefalosporinas/farmacologia , Cefalosporinas/uso terapêutico , Tazobactam/farmacologia , Tazobactam/uso terapêutico , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Infecções por Pseudomonas/tratamento farmacológico , Infecções por Pseudomonas/microbiologia , Testes de Sensibilidade Microbiana , Farmacorresistência Bacteriana Múltipla , Cefiderocol
11.
ChemMedChem ; 17(6): e202100644, 2022 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-34699131

RESUMO

Tuberculosis represents one of the ten most common courses of death worldwide and the emergence of multidrug-resistant M. tuberculosis makes the discovery of novel anti-tuberculosis active structures an urgent priority. Here, we show that (+)-floyocidin B representing the first example of a novel dihydroisoquinoline class of fungus-derived natural products, displays promising antitubercular hit properties. (+)-Floyocidin B was identified by activity-guided extract screening and its structure was unambiguously determined by total synthesis. The absolute configuration was deduced from a key synthesis intermediate by single crystal X-ray diffraction analysis. A hit series was generated by the isolation of further natural congeners and the synthesis of analogs of (+)-floyocidin B. Extensive biological and physicochemical profiling of this series revealed first structure-activity relationships and set the basis for further optimization and development of this novel antitubercular scaffold.


Assuntos
Produtos Biológicos , Mycobacterium tuberculosis , Tuberculose , Antituberculosos/química , Produtos Biológicos/farmacologia , Humanos , Testes de Sensibilidade Microbiana , Relação Estrutura-Atividade
12.
Microb Biotechnol ; 15(2): 415-430, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34165868

RESUMO

High-throughput platforms facilitating screening campaigns of environmental samples are needed to discover new products of natural origin counteracting the spreading of antimicrobial resistances constantly threatening human and agricultural health. We applied a combination of droplet microfluidics and fluorescence-activated cell sorting (FACS)-based technologies to access and assess a microbial environmental sample. The cultivation performance of our microfluidics workflow was evaluated in respect to the utilized cultivation media by Illumina amplicon sequencing of a pool of millions of droplets, respectively. This enabled the rational selection of a growth medium supporting the isolation of microbial diversity from soil (five phyla affiliated to 57 genera) including a member of the acidobacterial subgroup 1 (genus Edaphobacter). In a second phase, the entire diversity covered by 1071 cultures was used for an arrayed bioprospecting campaign, resulting in > 6000 extracts tested against human pathogens and agricultural pests. After redundancy curation by using a combinatorial chemical and genomic fingerprinting approach, we assigned the causative agents present in the extracts. Utilizing UHPLC-QTOF-MS/MS-guided fractionation and microplate-based screening assays in combination with molecular networking the production of bioactive ionophorous macrotetrolides, phospholipids, the cyclic lipopetides massetolides E, F, H and serratamolide A and many derivatives thereof was shown.


Assuntos
Produtos Biológicos , Microfluídica , Citometria de Fluxo/métodos , Ensaios de Triagem em Larga Escala/métodos , Humanos , Microfluídica/métodos , Extratos Vegetais , Espectrometria de Massas em Tandem
13.
J Antibiot (Tokyo) ; 75(10): 576-582, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36056265

RESUMO

Nine new hydroxyphenyloxazolines, madurastatin B4, C2, D3 and D4, E1 and E2, F1 as well as G1 and G2 (8-16), along with two new enantiomers of madurastatin D1 (ent-6) and D2 (ent-7) and two known congeners, madurastatin B1 (2) and C1 (5), were isolated from the liquid culture of Actinomadura sp. ST100801 based on the initial activity against Escherichia coli screened in bicarbonate-supplemented Mueller Hinton II medium and identification via molecular networking. Structure elucidation was achieved by comprehensive 1D and 2D NMR as well as MS/MS fragmentation analyses. Their absolute configuration was determined by Marfey's analysis. Complemented with functionalized hydroxyphenyloxazolines (2, 4, 17-18) obtained by total synthesis, the isolated compounds were evaluated for antibacterial activities revealing MICs down to 4 µg ml-1 against Moraxella catarrhalis. Therefore, this study enlarges the family of madurastatin siderophores.


Assuntos
Actinomadura , Sideróforos , Antibacterianos/química , Escherichia coli , Testes de Sensibilidade Microbiana , Estrutura Molecular , Espectrometria de Massas em Tandem
14.
Mol Microbiol ; 78(6): 1539-55, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21143323

RESUMO

In preparation for transfer conjugative type IV secretion systems (T4SS) produce a nucleoprotein adduct containing a relaxase enzyme covalently linked to the 5' end of single-stranded plasmid DNA. The bound relaxase is expected to present features necessary for selective recognition by the type IV coupling protein (T4CP), which controls substrate entry to the envelope spanning secretion machinery. We prove that the IncF plasmid R1 relaxase TraI is translocated to the recipient cells. Using a Cre recombinase assay (CRAfT) we mapped two internally positioned translocation signals (TS) on F-like TraI proteins that independently mediate efficient recognition and secretion. Tertiary structure predictions for the TS matched best helicase RecD2 from Deinococcus radiodurans. The TS is widely conserved in MOB(F) and MOB(Q) families of relaxases. Structure/function relationships within the TS were identified by mutation. A key residue in specific recognition by T4CP TraD was revealed by a fidelity switch phenotype for an F to plasmid R1 exchange L626H mutation. Finally, we show that physical linkage of the relaxase catalytic domain to a TraI TS is necessary for efficient conjugative transfer.


Assuntos
Conjugação Genética , DNA Helicases/química , DNA Helicases/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimologia , Escherichia coli/genética , DNA Helicases/genética , Escherichia coli/química , Proteínas de Escherichia coli/genética , Família Multigênica , Sinais Direcionadores de Proteínas , Estrutura Terciária de Proteína , Transporte Proteico
15.
Microorganisms ; 9(8)2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-34442721

RESUMO

Black soldier fly larvae (BSFL) are fast-growing, resilient insects that can break down a variety of organic substrates and convert them into valuable proteins and lipids for applications in the feed industry. Decomposition is mediated by an abundant and versatile gut microbiome, which has been studied for more than a decade. However, little is known about the phylogeny, properties and functions of bacterial isolates from the BSFL gut. We therefore characterized the BSFL gut microbiome in detail, evaluating bacterial diversity by culture-dependent methods and amplicon sequencing of the 16S rRNA gene. Redundant strains were identified by genomic fingerprinting and 105 non-redundant isolates were then tested for their ability to inhibit pathogens. We cultivated representatives of 26 genera, covering 47% of the families and 33% of the genera detected by amplicon sequencing. Among these isolates, we found several representatives of the most abundant genera: Morganella, Enterococcus, Proteus and Providencia. We also isolated diverse members of the less-abundant phylum Actinobacteria, and a novel genus of the order Clostridiales. We found that 15 of the isolates inhibited at least one of the tested pathogens, suggesting a role in helping to prevent colonization by pathogens in the gut. The resulting culture collection of unique BSFL gut bacteria provides a promising resource for multiple industrial applications.

16.
Sci Rep ; 10(1): 19614, 2020 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-33184304

RESUMO

The potential of sponge-associated bacteria for the biosynthesis of natural products with antibacterial activity was evaluated. In a preliminary screening 108 of 835 axenic isolates showed antibacterial activity. Active isolates were identified by 16S rRNA gene sequencing and selection of the most promising strains was done in a championship like approach, which can be done in every lab and field station without expensive equipment. In a competition assay, strains that inhibited most of the other strains were selected. In a second round, the strongest competitors from each host sponge competed against each other. To rule out that the best competitors selected in that way represent similar strains with the same metabolic profile, BOX PCR experiments were performed, and extracts of these strains were analysed using metabolic fingerprinting. This proved that the strains are different and have various metabolic profiles, even though belonging to the same genus, i.e. Bacillus. Furthermore, it was shown that co-culture experiments triggered the production of compounds with antibiotic activity, i.e. surfactins and macrolactin A. Since many members of the genus Bacillus possess the genetic equipment for the biosynthesis of these compounds, a potential synergism was analysed, showing synergistic effects between C14-surfactin and macrolactin A against methicillin-resistant Staphylococcus aureus (MRSA).


Assuntos
Antibacterianos/biossíntese , Antibacterianos/farmacologia , Bacillus/metabolismo , Poríferos/microbiologia , Animais , Bacillus/genética , Bacillus/isolamento & purificação , Farmacorresistência Bacteriana , Lipopeptídeos/biossíntese , Lipopeptídeos/farmacologia , Macrolídeos/metabolismo , Macrolídeos/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Peptídeos Cíclicos/biossíntese , Peptídeos Cíclicos/farmacologia
17.
Front Microbiol ; 11: 597628, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33240253

RESUMO

Microbial communities in the immediate environment of socialized invertebrates can help to suppress pathogens, in part by synthesizing bioactive natural products. Here we characterized the core microbiomes of three termite species (genus Coptotermes) and their nest material to gain more insight into the diversity of termite-associated bacteria. Sampling a healthy termite colony over time implicated a consolidated and highly stable microbiome, pointing toward the fact that beneficial bacterial phyla play a major role in termite fitness. In contrast, there was a significant shift in the composition of the core microbiome in one nest during a fungal infection, affecting the abundance of well-characterized Streptomyces species (phylum Actinobacteria) as well as less-studied bacterial phyla such as Acidobacteria. High-throughput cultivation in microplates was implemented to isolate and identify these less-studied bacterial phylogenetic group. Amplicon sequencing confirmed that our method maintained the bacterial diversity of the environmental samples, enabling the isolation of novel Acidobacteriaceae and expanding the list of cultivated species to include two strains that may define new species within the genera Terracidiphilus and Acidobacterium.

18.
J Bacteriol ; 191(22): 6888-99, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19767439

RESUMO

The mechanisms controlling progression of conjugative DNA processing from a preinitiation stage of specific plasmid strand cleavage at the transfer origin to a stage competent for unwinding the DNA strand destined for transfer remain obscure. Linear heteroduplex substrates containing double-stranded DNA binding sites for plasmid R1 relaxosome proteins and various regions of open duplex for TraI helicase loading were constructed to model putative intermediate structures in the initiation pathway. The activity of TraI was compared in steady-state multiple turnover experiments that measured the net production of unwound DNA as well as transesterase-catalyzed cleavage at nic. Helicase efficiency was enhanced by the relaxosome components TraM and integration host factor. The magnitude of stimulation depended on the proximity of the specific protein binding sites to the position of open DNA. The cytoplasmic domain of the R1 coupling protein, TraDDeltaN130, stimulated helicase efficiency on all substrates in a manner consistent with cooperative interaction and sequence-independent DNA binding. Variation in the position of duplex opening also revealed an unsuspected autoinhibition of the unwinding reaction catalyzed by full-length TraI. The activity reduction was sequence dependent and was not observed with a truncated helicase, TraIDeltaN308, lacking the site-specific DNA binding transesterase domain. Given that transesterase and helicase domains are physically tethered in the wild-type protein, this observation suggests that an intramolecular switch controls helicase activation. The data support a model where protein-protein and DNA ligand interactions at the coupling protein interface coordinate the transition initiating production and uptake of the nucleoprotein secretion substrate.


Assuntos
DNA Helicases/metabolismo , DNA Bacteriano/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Escherichia coli/metabolismo , Plasmídeos/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , DNA Helicases/genética , DNA Bacteriano/genética , Proteínas de Ligação a DNA/genética , Proteínas de Escherichia coli/genética , Fatores Hospedeiros de Integração/genética , Fatores Hospedeiros de Integração/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Modelos Biológicos
19.
J Bacteriol ; 191(22): 6877-87, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19767437

RESUMO

Selective substrate uptake controls initiation of macromolecular secretion by type IV secretion systems in gram-negative bacteria. Type IV coupling proteins (T4CPs) are essential, but the molecular mechanisms governing substrate entry to the translocation pathway remain obscure. We report a biochemical approach to reconstitute a regulatory interface between the plasmid R1 T4CP and the nucleoprotein relaxosome dedicated to the initiation stage of plasmid DNA processing and substrate presentation. The predicted cytosolic domain of T4CP TraD was purified in a predominantly monomeric form, and potential regulatory effects of this protein on catalytic activities exhibited by the relaxosome during transfer initiation were analyzed in vitro. TraDDeltaN130 stimulated the TraI DNA transesterase activity apparently via interactions on both the protein and the DNA levels. TraM, a protein interaction partner of TraD, also increased DNA transesterase activity in vitro. The mechanism may involve altered DNA conformation as TraM induced underwinding of oriT plasmid DNA in vivo (DeltaL(k) = -4). Permanganate mapping of the positions of duplex melting due to relaxosome assembly with TraDDeltaN130 on supercoiled DNA in vitro confirmed localized unwinding at nic but ruled out formation of an open complex compatible with initiation of the TraI helicase activity. These data link relaxosome regulation to the T4CP and support the model that a committed step in the initiation of DNA export requires activation of TraI helicase loading or catalysis.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Ligação a DNA/metabolismo , Plasmídeos/genética , Proteínas de Bactérias/genética , DNA Helicases/genética , DNA Helicases/metabolismo , DNA Bacteriano/química , DNA Bacteriano/metabolismo , Proteínas de Ligação a DNA/genética , Eletroforese em Gel de Ágar , Eletroforese em Gel Bidimensional , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Espectrometria de Massas , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Ligação Proteica
20.
Front Physiol ; 10: 438, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31057424

RESUMO

Aphids are economically important pest insects that damage plants by phloem feeding and the transmission of plant viruses. Their ability to feed exclusively on nutritionally poor phloem sap is dependent on the obligatory symbiotic bacterium Buchnera aphidicola, but additional facultative symbionts may also be present, a common example of which is Serratia symbiotica. Many Serratia species secrete extracellular enzymes, so we hypothesised that S. symbiotica may produce proteases that help aphids to feed on plants. Molecular analysis, including fluorescence in situ hybridization (FISH), revealed that S. symbiotica colonises the gut, salivary glands and mouthparts (including the stylet) of the pea aphid Acyrthosiphon pisum, providing a mechanism to transfer the symbiont into host plants. S. symbiotica was also detected in plant tissues wounded by the penetrating stylet and was transferred to naïve aphids feeding on plants containing this symbiont. The maintenance of S. symbiotica by repeated transmission via plants may explain the high frequency of this symbiont in aphid populations. Proteomic analysis of the supernatant from a related but cultivable S. symbiotica strain cultured in liquid medium revealed the presence of known and novel proteases including metalloproteases. The corresponding transcripts encoding these S. symbiotica enzymes were detected in A. pisum and in plants carrying the symbiont, although the mRNA was much more abundant in the aphids. Our data suggest that enzymes from S. symbiotica may facilitate the digestion of plant proteins, thereby helping to suppress plant defense, and that the symbionts are important mediators of aphid-plant interactions.

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