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Frontiers in Molecular Biosciences 2020The genus sensu lato is composed of a diverse and metabolically versatile group of bacterial species. One characteristic thought to be unique for the genus is the...
The genus sensu lato is composed of a diverse and metabolically versatile group of bacterial species. One characteristic thought to be unique for the genus is the presence of two forms each (with and without 2-hydroxylation) of the membrane lipids phosphatidylethanolamine (PE) and ornithine lipids (OLs). Here, we show that only sensu stricto strains constitutively form OLs, whereas all other analyzed strains belonging to the sensu lato group constitutively form the two forms of PE, but no OLs. We selected two model bacteria to study the function of OL in sensu lato: (1) wild-type which constitutively forms OLs and its mutant deficient in the formation of OLs and (2) (formerly ) which does not form OL constitutively, and a derived strain constitutively forming OLs. Both were characterized under free-living conditions and during pathogenic interactions with their respective hosts. The absence of OLs in slightly affected bacterial growth under specific abiotic stress conditions such as high temperature and low pH. lacking OLs caused lower mortality in larvae while constitutively forming OLs triggers an increased formation of reactive oxygen species immediately after infection of maize leaves, suggesting that OLs can have an important role during the activation of the innate immune response of eukaryotes.
PubMed: 33469548
DOI: 10.3389/fmolb.2020.610932 -
Clinical Microbiology and Infection :... Jul 2010Burkholderia cepacia complex (Bcc) bacteria have gained notoriety as pathogens in cystic fibrosis (CF) because they are difficult to identify and treat, and also have... (Review)
Review
Burkholderia cepacia complex (Bcc) bacteria have gained notoriety as pathogens in cystic fibrosis (CF) because they are difficult to identify and treat, and also have the ability to spread between CF individuals. Of the 17 formally named species within the complex, Burkholderia multivorans and Burkholderia cenocepacia dominate in CF. Multilocus sequence typing has proven to be a very useful tool for tracing the global epidemiology of Bcc bacteria and has shown that B. cenocepacia strains with high transmissibility, such as the ET-12 strain (ST-28) and the Czech strain (ST-32), have spread epidemically within CF populations in Canada and Europe. The majority of research on the molecular pathogenesis of Bcc bacteria has focused on the B. cenocepacia ET-12 epidemic lineage, with gene mutation, genome sequence analysis and, most recently, global gene expression studies shedding considerable light on the virulence and antimicrobial resistance of this pathogen. These studies demonstrate that the ability of B. cenocepacia to acquire foreign DNA (genomic islands, insertion sequences and other mobile elements), regulate gene expression via quorum sensing, compete for iron during infection, and mediate antimicrobial resistance and inflammation via its membrane and surface polysaccharides are key features that underpin the virulence of different strains. With the wealth of molecular knowledge acquired in the last decade on B. cenocepacia strains, we are now in a much better position to develop strategies for the treatment of pathogenic colonization with Bcc and to answer key questions on pathogenesis concerning, for example, the factors that trigger the rapid clinical decline in CF patients.
Topics: Burkholderia Infections; Burkholderia cenocepacia; Burkholderia cepacia complex; Canada; Cystic Fibrosis; Drug Resistance, Bacterial; Europe; Gene Expression; Humans; Interspersed Repetitive Sequences; Molecular Epidemiology; Multilocus Sequence Typing; Mutation; Polysaccharides, Bacterial; Quorum Sensing; Respiratory Tract Infections; Virulence
PubMed: 20880411
DOI: 10.1111/j.1469-0691.2010.03237.x -
Carbohydrate Research Jan 2021Burkholderia cenocepacia belongs to the Burkholderia Cepacia Complex, a group of 22 closely related species both of clinical and environmental origin, infecting cystic...
Burkholderia cenocepacia belongs to the Burkholderia Cepacia Complex, a group of 22 closely related species both of clinical and environmental origin, infecting cystic fibrosis patients. B. cenocepacia accounts for the majority of the clinical isolates, comprising the most virulent and transmissible strains. The capacity to form biofilms is among the many virulence determinants of B. cenocepacia, a characteristic that confers enhanced tolerance to some antibiotics, desiccation, oxidizing agents, and host defenses. Exopolysaccharides are a major component of biofilm matrices, particularly providing mechanical stability to biofilms. Recently, a water-insoluble exopolysaccharide produced by B. cenocepacia H111 in biofilm was characterized. In the present study, a water-soluble exopolysaccharide was extracted from B. cenocepacia H111 biofilm, and its structure was determined by GLC-MS, NMR and ESI-MS. The repeating unit is a linear rhamno-tetrasaccharide with 50% replacement of a 3-α-L-Rha with a α-3-L-Man. [2)-α-L-Rhap-(1→3)-α-L-[Rhap or Manp]-(1→3)-α-L-Rhap-(1→2)-α-L-Rhap-(1→] Molecular modelling was used to obtain information about local structural motifs which could give information about the polysaccharide conformation.
Topics: Biofilms; Burkholderia cenocepacia; Carbohydrate Conformation; Mannose; Models, Molecular; Polysaccharides, Bacterial; Rhamnose
PubMed: 33440288
DOI: 10.1016/j.carres.2020.108231 -
Microbiological Research Mar 2020Plant-growth promoting rhizobacteria benefit crop health and growth through various mechanisms including phosphate and potassium solubilisation, and antimicrobial...
Plant-growth promoting rhizobacteria benefit crop health and growth through various mechanisms including phosphate and potassium solubilisation, and antimicrobial activity. Previously, we sequenced the genome of bacterial strain Burkholderia cenocepacia CR318, which was isolated from the roots of the starch corn (Zea mays L.) in London, Ontario, Canada. In this work, the species identity of this isolate is confirmed by recA phylogeny and in silico DNA-DNA hybridization (isDDH), and its plant-growth promoting characteristics are described. B. cenocepacia CR318 exhibited strong activity of inorganic phosphate and potassium solubilization. It significantly promoted the growth of corn plants and roots by solubilizing inorganic tricalcium phosphate under greenhouse conditions. Functional analysis of the complete B. cenocepacia CR318 genome revealed genes associated with phosphate metabolism such as pstSCAB encoding a high affinity inorganic phosphate-specific transporter, and the pqqABCDE gene cluster involved in the biosynthesis of pyrroloquinoline quinone (PQQ), which is a required cofactor for quinoprotein glucose dehydrogenase (Gdh). However, it appears that B. cenocepacia CR318 lacks the quinoprotein Gdh which can produce gluconic acid to solubilize inorganic phosphate. Overall, these findings provide an important step in understanding the molecular mechanisms underlying the plant growth promotion trait of B. cenocepacia CR318.
Topics: Burkholderia cenocepacia; DNA, Bacterial; Genome, Bacterial; Glucose 1-Dehydrogenase; Ontario; PQQ Cofactor; Phosphates; Phylogeny; Plant Development; Plant Roots; Rhizosphere; Soil Microbiology; Solubility; Zea mays
PubMed: 31865096
DOI: 10.1016/j.micres.2019.126395 -
Applied and Environmental Microbiology May 2021Quorum-sensing (QS) signals are widely employed by bacteria to regulate biological functions in response to cell densities. Previous studies showed that Burkholderia...
Quorum-sensing (QS) signals are widely employed by bacteria to regulate biological functions in response to cell densities. Previous studies showed that Burkholderia cenocepacia mostly utilizes two types of QS systems, including the -acylhomoserine lactone (AHL) and -2-dodecenoic acid (BDSF) systems, to regulate biological functions. We demonstrated here that a LysR family transcriptional regulator, Bcal3178, controls the QS-regulated phenotypes, including biofilm formation and protease production, in B. cenocepacia H111. Expression of at the transcriptional level was obviously downregulated in both the AHL-deficient and BDSF-deficient mutant strains compared to the wild-type H111 strain. It was further identified that Bcal3178 regulated target gene expression by directly binding to the promoter DNA regions. We also revealed that Bcal3178 was directly controlled by the AHL system regulator CepR. These results show that Bcal3178 is a new downstream component of the QS signaling network that modulates a subset of genes and functions coregulated by the AHL and BDSF QS systems in B. cenocepacia. Burkholderia cenocepacia is an important opportunistic pathogen in humans that utilizes the BDSF and AHL quorum-sensing (QS) systems to regulate biological functions and virulence. We demonstrated here that a new downstream regulator, Bcal3178 of the QS signaling network, controls biofilm formation and protease production. Bcal3178 is a LysR family transcriptional regulator modulated by both the BDSF and AHL QS systems. Furthermore, Bcal3178 controls many target genes, which are regulated by the QS systems in B. cenocepacia. Collectively, our findings depict a novel molecular mechanism with which QS systems regulate some target gene expression and biological functions by modulating the expression level of a LysR family transcriptional regulator in B. cenocepacia.
Topics: Bacterial Proteins; Biofilms; Burkholderia cenocepacia; Gene Expression Regulation, Bacterial; Mutation; Peptide Hydrolases; Phenotype; Quorum Sensing; Transcription Factors
PubMed: 33811025
DOI: 10.1128/AEM.00202-21 -
Frontiers in Cellular and Infection... 2021The genus contains over 80 different Gram-negative species including both plant and human pathogens, the latter of which can be classified into one of two groups: the... (Review)
Review
The genus contains over 80 different Gram-negative species including both plant and human pathogens, the latter of which can be classified into one of two groups: the complex (Bpc) or the complex (Bcc). Bpc pathogens and are highly virulent, and both have considerable potential for use as Tier 1 bioterrorism agents; thus there is great interest in the development of novel vaccines and therapeutics for the prevention and treatment of these infections. While Bcc pathogens , , and are not considered bioterror threats, the incredible impact these infections have on the cystic fibrosis community inspires a similar demand for vaccines and therapeutics for the prevention and treatment of these infections as well. Understanding how these pathogens interact with and evade the host immune system will help uncover novel therapeutic targets within these organisms. Given the important role of the complement system in the clearance of bacterial pathogens, this arm of the immune response must be efficiently evaded for successful infection to occur. In this review, we will introduce the species to be discussed, followed by a summary of the complement system and known mechanisms by which pathogens interact with this critical system to evade clearance within the host. We will conclude with a review of literature relating to the interactions between the herein discussed species and the host complement system, with the goal of highlighting areas in this field that warrant further investigation.
Topics: Burkholderia; Burkholderia Infections; Burkholderia pseudomallei; Complement System Proteins; Humans; Immune Evasion; Melioidosis
PubMed: 34660335
DOI: 10.3389/fcimb.2021.701362 -
Microbiology (Reading, England) Sep 2009Burkholderia cenocepacia is a member of the B. cepacia complex (Bcc), a group of opportunistic bacteria that infect the airways of patients with cystic fibrosis (CF) and... (Review)
Review
Burkholderia cenocepacia is a member of the B. cepacia complex (Bcc), a group of opportunistic bacteria that infect the airways of patients with cystic fibrosis (CF) and are extraordinarily resistant to almost all clinically useful antibiotics. Infections in CF patients with Bcc bacteria generally lead to a more rapid decline in lung function, and in some cases to the 'cepacia syndrome', a virtually deadly exacerbation of the lung infection with systemic manifestations. These characteristics of Bcc bacteria contribute to higher morbidity and mortality in infected CF patients. In the last 10 years considerable progress has been made in understanding the interactions between Bcc bacteria and mammalian host cells. Bcc isolates can survive either intracellularly within eukaryotic cells or extracellularly in host tissues. They survive within phagocytes and respiratory epithelial cells, and they have the ability to breach the respiratory epithelium layer. Survival and persistence of Bcc bacteria within host cells and tissues are believed to play a key role in pulmonary infection and to contribute to the persistent inflammation observed in patients with CF. This review summarizes recent findings concerning the interaction between Bcc bacteria and epithelial and phagocytic cells.
Topics: Animals; Burkholderia Infections; Burkholderia cepacia complex; Cystic Fibrosis; Epithelial Cells; Host-Pathogen Interactions; Humans; Phagocytes; Respiratory System; Virulence
PubMed: 19542002
DOI: 10.1099/mic.0.031344-0 -
Frontiers in Cellular and Infection... 2023complex (Bcc) clonal complex (CC) 31, the predominant lineage causing devastating outbreaks globally, has been a growing concern of infections in non-cystic fibrosis...
INTRODUCTION
complex (Bcc) clonal complex (CC) 31, the predominant lineage causing devastating outbreaks globally, has been a growing concern of infections in non-cystic fibrosis (NCF) patients in India. is very challenging to treat owing to its virulence determinants and antibiotic resistance. Improving the management of these infections requires a better knowledge of their resistance patterns and mechanisms.
METHODS
Whole-genome sequences of 35 CC31 isolates obtained from patient samples, were analyzed against available 210 CC31 genomes in the NCBI database to glean details of resistance, virulence, mobile elements, and phylogenetic markers to study genomic diversity and evolution of CC31 lineage in India.
RESULTS
Genomic analysis revealed that 35 isolates belonging to CC31 were categorized into 11 sequence types (ST), of which five STs were reported exclusively from India. Phylogenetic analysis classified 245 CC31 isolates into eight distinct clades (I-VIII) and unveiled that NCF isolates are evolving independently from the global cystic fibrosis (CF) isolates forming a distinct clade. The detection rate of seven classes of antibiotic-related genes in 35 isolates was 35 (100%) for tetracyclines, aminoglycosides, and fluoroquinolones; 26 (74.2%) for sulphonamides and phenicols; 7 (20%) for beta-lactamases; and 1 (2.8%) for trimethoprim resistance genes. Additionally, 3 (8.5%) NCF isolates were resistant to disinfecting agents and antiseptics. Antimicrobial susceptibility testing revealed that majority of NCF isolates were resistant to chloramphenicol (77%) and levofloxacin (34%). NCF isolates have a comparable number of virulence genes to CF isolates. A well-studied pathogenicity island of . , GI11 is present in ST628 and ST709 isolates from the Indian Bcc population. In contrast, genomic island GI15 (highly similar to the island found in . strain EY1) is exclusively reported in ST839 and ST824 isolates from two different locations in India. Horizontal acquisition of lytic phage ST79 of pathogenic . is demonstrated in ST628 isolates Bcc1463, Bcc29163, and BccR4654 amongst CC31 lineage.
DISCUSSION
The study reveals a high diversity of CC31 lineages among isolates from India. The extensive information from this study will facilitate the development of rapid diagnostic and novel therapeutic approaches to manage . infections.
Topics: Humans; Burkholderia cenocepacia; Phylogeny; Burkholderia Infections; Burkholderia cepacia complex; Genomics; Anti-Infective Agents; Sepsis; Fibrosis
PubMed: 37153161
DOI: 10.3389/fcimb.2023.1151594 -
MSphere Aug 2022Interactions between different bacterial species shape bacterial communities and their environments. The opportunistic pathogens Pseudomonas aeruginosa and Burkholderia...
Interactions between different bacterial species shape bacterial communities and their environments. The opportunistic pathogens Pseudomonas aeruginosa and Burkholderia cenocepacia both can colonize the lungs of individuals affected by cystic fibrosis. Using the social surface behavior called swarming motility as a study model, we noticed intricate interactions between B. cenocepacia K56-2 and P. aeruginosa PA14. While strain K56-2 does not swarm under P. aeruginosa favorable swarming conditions, co-inoculation with a nonmotile PA14 flagellum-less Δ mutant restored spreading for both strains. We show that P. aeruginosa provides the wetting agent rhamnolipids allowing K56-2 to perform swarming motility, while aflagellated PA14 appears to "hitchhike" along with K56-2 cells in the swarming colony. Pseudomonas aeruginosa and Burkholderia cenocepacia are important opportunistic pathogens often found together in the airways of persons with cystic fibrosis. Laboratory cocultures of both species often ends with one taking over the other. We used a surface motility assay to study the social interactions between populations of these bacterial species. Under our conditions, B. cenocepacia cannot swarm without supplementation of the wetting agent produced by P. aeruginosa. In a mixed colony of both species, an aflagellated mutant of P. aeruginosa provides the necessary wetting agent to B. cenocepacia, allowing both bacteria to swarm and colonize a surface. We highlight this peculiar interaction where both bacteria set aside their antagonistic tendencies to travel together.
Topics: Burkholderia cenocepacia; Cystic Fibrosis; Flagella; Humans; Pseudomonas aeruginosa; Wetting Agents
PubMed: 35862793
DOI: 10.1128/msphere.00153-22 -
Current Research in Structural Biology 2021Epoxide hydrolases catalyze the conversion of epoxides to vicinal diols in a range of cellular processes such as signaling, detoxification, and virulence. These enzymes...
Epoxide hydrolases catalyze the conversion of epoxides to vicinal diols in a range of cellular processes such as signaling, detoxification, and virulence. These enzymes typically utilize a pair of tyrosine residues to orient the substrate epoxide ring in the active site and stabilize the hydrolysis intermediate. A new subclass of epoxide hydrolases that utilize a histidine in place of one of the tyrosines was established with the discovery of the CFTR Inhibitory Factor (Cif) from . Although the presence of such Cif-like epoxide hydrolases was predicted in other opportunistic pathogens based on sequence analyses, only Cif and its homolog aCif from have been characterized. Here we report the biochemical and structural characteristics of Cfl1 and Cfl2, two Cif-like epoxide hydrolases from . Cfl1 is able to hydrolyze xenobiotic as well as biological epoxides that might be encountered in the environment or during infection. In contrast, Cfl2 shows very low activity against a diverse set of epoxides. The crystal structures of the two proteins reveal quaternary structures that build on the well-known dimeric assembly of the α/β hydrolase domain, but broaden our understanding of the structural diversity encoded in novel oligomer interfaces. Analysis of the interfaces reveals both similarities and key differences in sequence conservation between the two assemblies, and between the canonical dimer and the novel oligomer interfaces of each assembly. Finally, we discuss the effects of these higher-order assemblies on the intra-monomer flexibility of Cfl1 and Cfl2 and their possible roles in regulating enzymatic activity.
PubMed: 34235487
DOI: 10.1016/j.crstbi.2021.02.002