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Virulence Aug 2017
Topics: Burkholderia Infections; Burkholderia cenocepacia; Burkholderia cepacia complex; Cystic Fibrosis; Humans; Lung; Virulence
PubMed: 27786605
DOI: 10.1080/21505594.2016.1253660 -
Applied Microbiology and Biotechnology Jun 2023Small non-coding RNAs (sRNAs) are key regulators of post-transcriptional gene expression in bacteria. Despite the identification of hundreds of bacterial sRNAs, their...
Small non-coding RNAs (sRNAs) are key regulators of post-transcriptional gene expression in bacteria. Despite the identification of hundreds of bacterial sRNAs, their roles on bacterial physiology and virulence remain largely unknown, as is the case of bacteria of the Burkholderia cepacia complex (Bcc). Bcc is a group of opportunistic pathogens with relatively large genomes that can cause lethal lung infections amongst cystic fibrosis (CF) patients. To characterise sRNAs expressed by Bcc bacteria when infecting a host, the nematode Caenorhabditis elegans was used as an infection model by the epidemic CF strain B. cenocepacia J2315. A total of 108 new and 31 previously described sRNAs with a predicted Rho independent terminator were identified, most of them located on chromosome 1. RIT11b, a sRNA downregulated under C. elegans infection conditions, was shown to directly affect B. cenocepacia virulence, biofilm formation, and swimming motility. RIT11b overexpression reduced the expression of the direct targets dusA and pyrC, involved in biofilm formation, epithelial cell adherence, and chronic infections in other organisms. The in vitro direct interaction of RIT11b with the dusA and pyrC messengers was demonstrated by electrophoretic mobility shift assays. To the best of our knowledge this is the first report on the functional characterization of a sRNA directly involved in B. cenocepacia virulence. KEY POINTS: • 139 sRNAs expressed by B. cenocepacia during C. elegans infection were identified • The sRNA RIT11b affects B. cenocepacia virulence, biofilm formation, and motility • RIT11b directly binds to and regulates dusA and pyrC mRNAs.
Topics: Animals; Humans; Burkholderia cenocepacia; Caenorhabditis elegans; Burkholderia cepacia complex; RNA, Small Untranslated; Burkholderia Infections
PubMed: 37097504
DOI: 10.1007/s00253-023-12530-3 -
MicrobiologyOpen Jul 2019Burkholderia cenocepacia is an opportunistic bacterial pathogen that poses a significant threat to individuals with cystic fibrosis by provoking a strong inflammatory...
Burkholderia cenocepacia is an opportunistic bacterial pathogen that poses a significant threat to individuals with cystic fibrosis by provoking a strong inflammatory response within the lung. It possesses a type VI secretion system (T6SS), a secretory apparatus that can perforate the cellular membrane of other bacterial species and/or eukaryotic targets, to deliver an arsenal of effector proteins. The B. cenocepacia T6SS (T6SS-1) has been shown to be implicated in virulence in rats and contributes toward actin rearrangements and inflammasome activation in B. cenocepacia-infected macrophages. Here, we present bioinformatics evidence to suggest that T6SS-1 is the archetype T6SS in the Burkholderia genus. We show that B. cenocepacia T6SS-1 is active under normal laboratory growth conditions and displays antibacterial activity against other Gram-negative bacterial species. Moreover, B. cenocepacia T6SS-1 is not required for virulence in three eukaryotic infection models. Bioinformatics analysis identified several candidate T6SS-dependent effectors that may play a role in the antibacterial activity of B. cenocepacia T6SS-1. We conclude that B. cenocepacia T6SS-1 plays an important role in bacterial competition for this organism, and probably in all Burkholderia species that possess this system, thereby broadening the range of species that utilize the T6SS for this purpose.
PubMed: 30628184
DOI: 10.1002/mbo3.774 -
Boletin Medico Del Hospital Infantil de... 2022Cystic fibrosis is an autosomal recessive inherited disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). CFTR is a protein... (Review)
Review
Cystic fibrosis is an autosomal recessive inherited disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). CFTR is a protein that transports ions across the membrane of lung epithelial cells. Loss of its function leads to the production of thick sticky mucus, where various bacterial pathogens can establish and adapt, contributing to the gradual loss of lung function. In this review, evidence of the molecular mechanisms used by Pseudomonas aeruginosa and Burkholderia cenocepacia to survive and persist in the pulmonary environment will be provided. Additionally, new therapeutic strategies based on CFTR function modulators will be described.
Topics: Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Epithelial Cells; Fibrosis; Humans; Pseudomonas aeruginosa
PubMed: 36100204
DOI: 10.24875/BMHIM.21000128 -
BMC Genomics Nov 2019Burkholderia cenocepacia is a human opportunistic pathogen causing devastating symptoms in patients suffering from immunodeficiency and cystic fibrosis. Out of the 303...
BACKGROUND
Burkholderia cenocepacia is a human opportunistic pathogen causing devastating symptoms in patients suffering from immunodeficiency and cystic fibrosis. Out of the 303 B. cenocepacia strains with available genomes, the large majority were isolated from a clinical context. However, several isolates originate from other environmental sources ranging from aerosols to plant endosphere. Plants can represent reservoirs for human infections as some pathogens can survive and sometimes proliferate in the rhizosphere. We therefore investigated if B. cenocepacia had the same potential.
RESULTS
We selected genome sequences from 31 different strains, representative of the diversity of ecological niches of B. cenocepacia, and conducted comparative genomic analyses in the aim of finding specific niche or host-related genetic determinants. Phylogenetic analyses and whole genome average nucleotide identity suggest that strains, registered as B. cenocepacia, belong to at least two different species. Core-genome analyses show that the clade enriched in environmental isolates lacks multiple key virulence factors, which are conserved in the sister clade where most clinical isolates fall, including the highly virulent ET12 lineage. Similarly, several plant associated genes display an opposite distribution between the two clades. Finally, we suggest that B. cenocepacia underwent a host jump from plants/environment to animals, as supported by the phylogenetic analysis. We eventually propose a name for the new species that lacks several genetic traits involved in human virulence.
CONCLUSION
Regardless of the method used, our studies resulted in a disunited perspective of the B. cenocepacia species. Strains currently affiliated to this taxon belong to at least two distinct species, one having lost several determining animal virulence factors.
Topics: Adaptation, Physiological; Burkholderia cenocepacia; Evolution, Molecular; Host-Pathogen Interactions; Humans; Phylogeny; Plants; Virulence
PubMed: 31684866
DOI: 10.1186/s12864-019-6186-z -
Thorax Nov 2004Burkholderia cepacia infection has been associated with a poor prognosis for patients with cystic fibrosis (CF). It is now recognised that organisms classified as B...
INTRODUCTION
Burkholderia cepacia infection has been associated with a poor prognosis for patients with cystic fibrosis (CF). It is now recognised that organisms classified as B cepacia comprise a number of distinct genomic species each known as a genomovar of the B cepacia complex (BCC). The outcome of infection for CF patients with individual genomovars is unknown. The clinical outcome of infection with the two most commonly isolated genomovars (B cenocepacia and B multivorans) was studied at a specialist CF centre between 1982 and 2003.
METHODS
The numbers of patients who progressed from initial to chronic infection were assessed. Control groups were created by matching patients with chronic BCC infection by percentage forced expiratory volume in 1 second with patients with Pseudomonas aeruginosa infection. Outcome measures were survival time, deaths from "cepacia syndrome", rate of decline in spirometry and body mass index (BMI), and treatment requirements.
RESULTS
Forty nine patients had an initial infection with either B multivorans (n = 16) or B cenocepacia (n = 33); 8/16 and 31/33, respectively, developed chronic infection (p<0.001). Deaths from "cepacia syndrome" occurred in both BCC groups. Patients with B cenocepacia infection had a shorter survival than patients with P aeruginosa infection (p = 0.01). There was no difference in survival between CF patients infected with B multivorans and P aeruginosa. There were no observed differences in changes in spirometry and BMI or treatment requirements between the BCC groups and respective controls.
CONCLUSION
In CF, the genomovar status of BCC may influence both the likelihood of progression from initial to chronic infection and the overall survival of the patients.
Topics: Adult; Burkholderia Infections; Burkholderia cepacia; Burkholderia cepacia complex; Cystic Fibrosis; Female; Forced Expiratory Volume; Humans; Male; Prognosis; Survival Analysis; Vital Capacity
PubMed: 15516469
DOI: 10.1136/thx.2003.017210 -
AMB Express May 2019The inability of the yeast Saccharomyces cerevisiae to produce ethanol from xylose has hampered the biofuel production from lignocellulosic biomass. However, prior...
The inability of the yeast Saccharomyces cerevisiae to produce ethanol from xylose has hampered the biofuel production from lignocellulosic biomass. However, prior studies reveal that functional expression of xylose isomerase (XI) from Burkholderia cenocepacia (XylA) in S. cerevisiae has remarkably improved xylose consumption and ethanol productivity. Yet, little is known about kinetic and structural properties of this enzyme. Hereby, a purified recombinant XylA was assayed in vitro, showing optimal enzyme activity at 37 °C and pH 7.2. The K of XylA for D-xylose was at least threefold lower than the K results for any XI published to date (e.g. XylA from Piromyces sp.). In addition, oligomerization behavior as a tetramer was observed for XylA in solution. Functional and structural comparative analyses amongst three microbial XIs were further performed as theoretical models, showing that xylose orientation at the active site was highly conserved among the XIs. Mg ions anchor the sugar and guide its pyranoside oxygen towards a histidine residue present at the active site, allowing an acid-base reaction, linearizing xylose. Electrostatic surface analyses showed that small variations in the net charge distribution and dipole moment could directly affect the way the substrate interacts with the protein, thus altering its kinetic properties. Accordingly, in silico modeling suggested the tetramer may be the major functional form. These analyses and the resulting model promote a better understanding of this protein family and pave the way to further protein engineering and application of XylA in the ethanol industry.
PubMed: 31127459
DOI: 10.1186/s13568-019-0795-4 -
Cellular Microbiology Mar 2014Selective autophagy functions to specifically degrade cellular cargo tagged by ubiquitination, including bacteria. Strains of the Burkholderia cepacia complex (Bcc) are...
Selective autophagy functions to specifically degrade cellular cargo tagged by ubiquitination, including bacteria. Strains of the Burkholderia cepacia complex (Bcc) are opportunistic pathogens that cause life-threatening infections in patients with cystic fibrosis (CF) and chronic granulomatous disease (CGD). While there is evidence that defective macrophage autophagy in a mouse model of CF can influence B. cenocepacia susceptibility, there have been no comprehensive studies on how this bacterium is sensed and targeted by the host autophagy response in human macrophages. Here, we describe the intracellular life cycle of B. cenocepacia J2315 and its interaction with the autophagy pathway in human cells. Electron and confocal microscopy analyses demonstrate that the invading bacteria interact transiently with the endocytic pathway before escaping to the cytosol. This escape triggers theselective autophagy pathway, and the recruitment of ubiquitin, the ubiquitin-binding adaptors p62 and NDP52 and the autophagosome membrane-associated protein LC3B, to the bacterial vicinity. However, despite recruitment of these key autophagy pathway effectors, B. cenocepacia blocks autophagosome completion and replicates in the host cytosol. We find that a pre-infection increase in cellular autophagy flux can significantly inhibit B. cenocepacia replication and that lower autophagy flux in macrophages from immunocompromised CGD patients could contribute to increased B. cenocepacia susceptibility, identifying autophagy manipulation as a potential therapeutic approach to reduce bacterial burden in B. cenocepacia infections.
Topics: Adaptor Proteins, Signal Transducing; Animals; Autophagy; Burkholderia Infections; Burkholderia cenocepacia; Cell Line; Cytosol; Disease Models, Animal; Endoplasmic Reticulum; Humans; Immune Evasion; Macrophages; Mice; Mice, Inbred C57BL; Microtubule-Associated Proteins; Nuclear Proteins; RNA Interference; RNA, Small Interfering; Sequestosome-1 Protein
PubMed: 24119232
DOI: 10.1111/cmi.12223 -
PloS One 2020Regulatory small RNAs play an essential role in maintaining cell homeostasis in bacteria in response to environmental stresses such as iron starvation. Prokaryotes...
Regulatory small RNAs play an essential role in maintaining cell homeostasis in bacteria in response to environmental stresses such as iron starvation. Prokaryotes generally encode a large number of RNA regulators, yet their identification and characterisation is still in its infancy for most bacterial species. Burkholderia cenocepacia is an opportunistic pathogen with high innate antimicrobial resistance, which can cause the often fatal cepacia syndrome in individuals with cystic fibrosis. In this study we characterise a small RNA which is involved in the response to iron starvation, a condition that pathogenic bacteria are likely to encounter in the host. BrrF is a small RNA highly upregulated in Burkholderia cenocepacia under conditions of iron depletion and with a genome context consistent with Fur regulation. Its computationally predicted targets include iron-containing enzymes of the tricarboxylic acid (TCA) cycle such as aconitase and succinate dehydrogenase, as well as iron-containing enzymes responsible for the oxidative stress response, such as superoxide dismutase and catalase. Phenotypic and gene expression analysis of BrrF deletion and overexpression mutants show that the regulation of these genes is BrrF-dependent. Expression of acnA, fumA, sdhA and sdhC was downregulated during iron depletion in the wild type strain, but not in a BrrF deletion mutant. TCA cycle genes not predicted as target for BrrF were not affected in the same manner by iron depletion. Likewise, expression of sodB and katB was dowregulated during iron depletion in the wild type strain, but not in a BrrF deletion mutant. BrrF overexpression reduced aconitase and superoxide dismutase activities and increased sensitivity to hydrogen peroxide. All phenotypes and gene expression changes of the BrrF deletion mutant could be complemented by overexpressing BrrF in trans. Overall, BrrF acts as a regulator of central metabolism and oxidative stress response, possibly as an iron-sparing measure to maintain iron homeostasis under conditions of iron starvation.
Topics: Aconitate Hydratase; Bacterial Proteins; Burkholderia cenocepacia; Catalase; Gene Expression Regulation, Bacterial; Humans; Hydrogen Peroxide; Iron; Oxidative Stress; RNA, Small Untranslated; Superoxide Dismutase
PubMed: 32702060
DOI: 10.1371/journal.pone.0236405 -
Journal of Bacteriology Oct 2016Microbial adaptation is conspicuous in essentially every environment, but the mechanisms of adaptive evolution are poorly understood. Studying evolution in the... (Review)
Review
Microbial adaptation is conspicuous in essentially every environment, but the mechanisms of adaptive evolution are poorly understood. Studying evolution in the laboratory under controlled conditions can be a tractable approach, particularly when new, discernible phenotypes evolve rapidly. This is especially the case in the spatially structured environments of biofilms, which promote the occurrence and stability of new, heritable phenotypes. Further, diversity in biofilms can give rise to nascent social interactions among coexisting mutants and enable the study of the emerging field of sociomicrobiology. Here, we review findings from laboratory evolution experiments with either Pseudomonas fluorescens or Burkholderia cenocepacia in spatially structured environments that promote biofilm formation. In both systems, ecotypes with overlapping niches evolve and produce competitive or facilitative interactions that lead to novel community attributes, demonstrating the parallelism of adaptive processes captured in the lab.
Topics: Biofilms; Burkholderia cenocepacia; Directed Molecular Evolution; Pseudomonas fluorescens
PubMed: 27044625
DOI: 10.1128/JB.01018-15