The Third Replicon of Members of the Burkholderia cepacia Complex, Plasmid pC3, Plays a Role in Stress Tolerance

Agnoli, Kirsty; Frauenknecht, Carmen; Freitag, Roman; Schwager, Stephan; Jenul, Christian; Vergunst, Annette C.; Carlier, Aurélien; Eberl, Leo

doi:10.1128/aem.03330-13

Cited by 33 publications

(49 citation statements)

References 29 publications

(43 reference statements)

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“…To test this hypothesis, we used an established strategy to confirm the presence of the third replicon based on a PCR screen with primer pairs used sequentially and designed to anneal to the highly conserved region concerning its replication origin. 27 With the exception of IST4129, all the other isolates gave a positive PCR result for the presence of this megaplasmid with the first set of primers (repAFor and repARev) ( Supplementary Fig. 2A).…”

Section: Resultsmentioning

confidence: 94%

“…26 This result strongly suggests, for the first time, the in vivo loss of the nonessential virulence third replicon in B. cenocepacia. Based on previous studies 26,27 and in the screening performed in this work comprising the 39 isolates examined throughout this study plus 20 5 additional isolates from patients AB and AN, all of them found to have the third replicon, it is possible to conclude that the in vivo loss of this megaplasmid, although possible, is a rare event.…”

Section: Discussionmentioning

confidence: 91%

“…The hypothesis put forward was that B. cenocepacia third replicon, previously described as encoding virulence factors, besides secondary metabolism and other accessory functions, 26,27 could be missing in IST4129, or could at least be missing a portion of this replicon that includes the aidA gene. To test this hypothesis, we used an established strategy to confirm the presence of the third replicon based on a PCR screen with primer pairs used sequentially and designed to anneal to the highly conserved region concerning its replication origin.…”

Section: Resultsmentioning

confidence: 99%

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Variation ofBurkholderia cenocepaciavirulence potential during cystic fibrosis chronic lung infection

et al. 2016

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During long-term lung infection in cystic fibrosis (CF) patients, Burkholderia cenocepacia faces multiple selective pressures in this highly stressful and fluctuating environment. As a consequence, the initial infecting strain undergoes genetic changes that result in the diversification of genotypes and phenotypes. Whether this clonal expansion influences the pathogenic potential is unclear. The virulence potential of 39 sequential B. cenocepacia (recA lineage IIIA) isolates, corresponding to 3 different clones retrieved from 3 chronically infected CF patients was compared in this study using the non-mammalian infection hosts Galleria mellonella and Caenorhabditis elegans. The isolates used in this retrospective study were picked randomly from selective agar plates as part of a CF Center routine, from the onset of infection until patients' death after 3.5 and 7.5 y or the more recent isolation date after 12.5 y of chronic infection. The infection models proved useful to assess virulence potential diversification, but for some isolates the relative values diverged in C. elegans and G. mellonella. Results also reinforce the concept of the occurrence of clonal diversification and co-existence of multiple phenotypes within the CF lungs, also with respect to pathogenicity. No clear trend of decrease (or increase) of the virulence potential throughout long-term infection was found but there is an apparent tendency for a clone/patient-dependent decrease of virulence when the G. mellonella model was used. The sole avirulent variant in both infection hosts was found to lack the small third replicon previously associated to virulence. Although possible, the in vivo loss of this nonessential megaplasmid was found to be a rare event (1 among a total of 64 isolates examined).

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Section: Resultsmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

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Variation ofBurkholderia cenocepaciavirulence potential during cystic fibrosis chronic lung infection

et al. 2016

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“…The Bcc genome is large (nearly 8 Mb for Burkholderia cenocepacia H111) and consists of at least three replicons; these are chromosomes 1 and 2 and the megaplasmid pC3. pC3 was previously known as chromosome 3 but has been found to be nonessential in every Bcc strain investigated so far (9,10). The large Bcc genome size and multireplicon structure enable Bcc strains to thrive in a range of different niches, both agricultural and medical.…”

mentioning

confidence: 99%

“…The less-conserved secondary chromosome contains genes important for niche adaptation of individual Bcc strains, whereas megaplasmid pC3 has roles in virulence and antifungal activity in various Bcc species, which are, to various degrees, dependent on the strain (9,10). It has also been shown to be important for stress tolerance in B. cenocepacia H111 (10). A number of wellcharacterized genes and clusters contributing to these phenotypes are carried by pC3.…”

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confidence: 99%

Use of Synthetic Hybrid Strains To Determine the Role of Replicon 3 in Virulence of the Burkholderia cepacia Complex

Agnoli

Freitag

Gomes

et al. 2017

Appl Environ Microbiol

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The Burkholderia cepacia complex (Bcc) displays a wealth of metabolic diversity with great biotechnological potential, but the utilization of these bacteria is limited by their opportunistic pathogenicity to humans. The third replicon of the Bcc, megaplasmid pC3 (0.5 to 1.4 Mb, previously chromosome 3), is important for various phenotypes, including virulence, antifungal, and proteolytic activities and the utilization of certain substrates. Approximately half of plasmid pC3 is well conserved throughout sequenced Bcc members, while the other half is not. To better locate the regions responsible for the key phenotypes, pC3 mutant derivatives of Burkholderia cenocepacia H111 carrying large deletions (up to 0.58 Mb) were constructed with the aid of the FLP-FRT (FRT, flippase recognition target) recombination system from Saccharomyces cerevisiae. The conserved region was shown to confer near-full virulence in both Caenorhabditis elegans and Galleria mellonella infection models. Antifungal activity was unexpectedly independent of the part of pC3 bearing a previously identified antifungal gene cluster, while proteolytic activity was dependent on the nonconserved part of pC3, which encodes the ZmpA protease. To investigate to what degree pC3-encoded functions are dependent on chromosomally encoded functions, we transferred pC3 from Burkholderia cenocepacia K56-2 and Burkholderia lata 383 into other pC3-cured Bcc members. We found that although pC3 is highly important for virulence, it was the genetic background of the recipient that determined the pathogenicity level of the hybrid strain. Furthermore, we found that important phenotypes, such as antifungal activity, proteolytic activity, and some substrate utilization capabilities, can be transferred between Bcc members using pC3. IMPORTANCEThe Burkholderia cepacia complex (Bcc) is a group of closely related bacteria with great biotechnological potential. Some strains produce potent antifungal compounds and can promote plant growth or degrade environmental pollutants. However, their agricultural potential is limited by their opportunistic pathogenicity, particularly for cystic fibrosis patients. Despite much study, their virulence remains poorly understood. The third replicon, pC3, which is present in all Bcc isolates and is important for pathogenicity, stress resistance, and the production of antifungal compounds, has recently been reclassified from a chromosome to a megaplasmid. In this study, we identified regions on pC3 important for virulence and antifungal activity and investigated the role of the chromosomal background for the function of pC3 by exchanging the megaplasmid between different Bcc members. Our results may open a new avenue for the construction of antifungal but nonpathogenic Burkholderia hybrids. Such strains may have great potential as biocontrol strains for protecting fungus-borne diseases of plant crops.

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Burkholderia

Vandamme¹,

Eberl²

2018

Bergey's Manual of Systematics of Archaea and Bacteria

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Burk.hol.de'ri.a. N.L. fem. n. Burkholderia named after W. H. Burkholder, American bacteriologist who discovered the etiological agent of onion rot. Proteobacteria / Betaproteobacteria / Burkholderiales / Burkholderiaceae / Burkholderia The genus Burkholderia now groups more than 100 species with extraordinary metabolic capacities, and which occupy a bewildering array of ecological niches. The sources from which Burkholderia species have been isolated are manifold, but the accumulated evidence suggests that soil, where Burkholderia can be associated with a wide range of plants and fungi, is its natural habitat. The genus comprises two class‐3 pathogens, Burkholderia mallei and Burkholderia pseudomallei , but a growing number of Burkholderia species has been reported as opportunistic pathogens in humans. Burkholderia bacteria appear to have a predilection for the respiratory tract as life‐threatening lung infections occur in individuals with cystic fibrosis or chronic granulomatous disease, and in patients requiring mechanical ventilation. Burkholderia bacteria have rightfully been referred to as both friend and foe to humans. While the first Burkholderia species were primarily known as plant, human, and animal pathogens, subsequent studies revealed their biotechnological potential for plant growth promotion, biocontrol of various plant pests, and bioremediation. Because of this wide interest, an unusual number of whole‐genome sequences has become available, yet generally failed to reveal the difference between good or bad, or alternatively, biotechnologically safe or unsafe, species or strains. The phylogenetic diversity within this genus was recently used as an argument to reclassify the large majority of Burkholderia species into Burkholderia sensu stricto and the novel genera Caballeronia, Paraburkholderia , and Robbsia . Except for the latter, each of genera consists of environmental species of which a growing number is reported to cause infections in humans. DNA G + C content (mol%) : 64–69. Type species : Burkholderia cepacia (Palleroni and Holmes 1981) Yabuuchi, Kosako, Oyaizu, Yano, Hotta, Hashimoto, Ezaki and Arakawa 1993, 398 VP (Effective publication: Yabuuchi, Kosako, Oyaizu, Yano, Hotta, Hashimoto, Ezaki and Arakawa 1992, 1271) ( Pseudomonas cepacia Palleroni and Holmes 1981, 479).

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The Third Replicon of Members of the Burkholderia cepacia Complex, Plasmid pC3, Plays a Role in Stress Tolerance

Cited by 33 publications

References 29 publications

Variation ofBurkholderia cenocepaciavirulence potential during cystic fibrosis chronic lung infection

Variation ofBurkholderia cenocepaciavirulence potential during cystic fibrosis chronic lung infection

Use of Synthetic Hybrid Strains To Determine the Role of Replicon 3 in Virulence of the Burkholderia cepacia Complex

Burkholderia

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