Determination of copy number and circularization ratio of Tn<i>916</i>-Tn<i>1545</i> family of conjugative transposons in oral streptococci by droplet digital PCR

Lunde, Tracy Munthali; Roberts, Adam P.; Al‐Haroni, Mohammed

doi:10.1080/20002297.2018.1552060

Cited by 6 publications

(6 citation statements)

References 42 publications

(53 reference statements)

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“…We suspect that having two copies of Tn 916 exacerbated the growth phenotypes following Tn 916 activation. It is likely that the activation and excision of one copy of Tn 916 leads to activation and excision of the second copy [ 36 , 59 , 60 ]. Thus, having two copies of Tn 916 in a host cell likely leads to higher expression levels of detrimental gene(s), which could be deleterious for the host.…”

Section: Resultsmentioning

confidence: 99%

Activation of the integrative and conjugative element Tn916 causes growth arrest and death of host bacteria

Bean

McLellan²,

Grossman³

2022

PLoS Genet

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Integrative and conjugative elements (ICEs) serve as major drivers of bacterial evolution. These elements often confer some benefit to host cells, including antibiotic resistance, metabolic capabilities, or pathogenic determinants. ICEs can also have negative effects on host cells. Here, we investigated the effects of the ICE (conjugative transposon) Tn916 on host cells. Because Tn916 is active in a relatively small subpopulation of host cells, we developed a fluorescent reporter system for monitoring activation of Tn916 in single cells. Using this reporter, we found that cell division was arrested in cells of Bacillus subtilis and Enterococcus faecalis (a natural host for Tn916) that contained an activated (excised) Tn916. Furthermore, most of the cells with the activated Tn916 subsequently died. We also observed these phenotypes on the population level in B. subtilis utilizing a modified version of Tn916 that can be activated in the majority of cells. We identified two genes (orf17 and orf16) in Tn916 that were sufficient to cause growth defects in B. subtilis and identified a single gene, yqaR, that is in a defective phage (skin) in the B. subtilis chromosome that was required for this phenotype. These three genes were only partially responsible for the growth defect caused by Tn916, indicating that Tn916 possesses multiple mechanisms to affect growth and viability of host cells. These results highlight the complex relationships that conjugative elements have with their host cells and the interplay between mobile genetic elements.

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Section: Resultsmentioning

confidence: 99%

Activation of the integrative and conjugative element Tn916 causes growth arrest and death of host bacteria

Bean

McLellan²,

Grossman³

2022

PLoS Genet

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“…The in vivo transferability of the Tn 916 -Tn 1545 family was investigated by filter mating experiments in which both laboratory and clinical isolates were used as donor strains. The strain B. subtilis BS49 was included in this study as a control strain for the transfer of Tn 916 as this element is known to be transferable with a CR of 9.7% [ 41 ], and exists as two copies [ 45 ]. To evaluate the transferability of Tn 916 -Tn 1545 elements in the clinical setting, we used clinical isolates harboring the wild type Tn 916 as donor strains in the conjugation experiments.…”

Section: Resultsmentioning

confidence: 99%

“…The primers used in this PCR are designed to produce an amplicon only when the element has been excised from the chromosome and the left and right junctions of the element join to form the CI. The CR was determined by ddPCR as previously described by Lunde et al [ 41 ] and expressed as a ratio of CI to the number of the Tn 916 -Tn 1545 family elements that were present in a bacterial population.…”

Section: Methodsmentioning

confidence: 99%

Prevalence, diversity and transferability of the Tn916-Tn1545 family ICE in oral streptococci

Lunde

Hjerde

Al‐Haroni

2021

Journal of Oral Microbiology

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Background: The Tn916-Tn1545 family of Integrative Conjugative Elements (ICE) are mobile genetic elements (MGEs) that play a role in the spread of antibiotic resistance genes. The Tn916 harbors the tetracycline resistance gene tet(M) and it has been reported in various bacterial species. The increase in the levels of tetracycline resistance among oral streptococci is of great concern primarily due to the abundance of these species in the oral cavity and their ability to act as reservoirs for antibiotic resistance genes. Methods: In the current study, we screened 100 Norwegian clinical oral streptococcal isolates for the presence and diversity of the Tn916-Tn1545 family. In addition, we investigated the transferability the elements, and the associated transfer frequencies. Results: We observed that 21 isolates harboured the Tn916-Tn1545 family and that two of these elements were the novel Tn6815 and Tn6816. The most prevalent member of the Tn916-Tn1545 family observed in the Norwegian clinical oral streptococcal isolates was the wild type Tn916. Conclusion: The detection of other members of this family of ICE and varying transfer frequencies suggests high versatility of the Tn916 element in oral streptococci in Norway.

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“…We predict that having two copies of Tn 916 exacerbates the growth phenotypes following Tn 916 activation. It is likely that the activation and excision of one copy of Tn 916 leads to activation and excision of the second copy (Flannagan and Clewell, 1991; Lunde et al, 2019; Manganelli et al, 1995). Thus, having two copies of Tn 916 in a host cell likely leads to higher expression levels of detrimental gene(s), which could be deleterious for the host.…”

Section: Host Cells Lacking Orf17-16 or Yqar Exhibit Growth Defects U...mentioning

confidence: 99%

Activation of the integrative and conjugative element Tn916causes growth arrest and death of host bacteria

Bean

McLellan

Grossman

2022

Preprint

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Integrative and conjugative elements (ICEs) serve as major drivers of bacterial evolution. These elements often confer some benefit to a host cell, including antibiotic resistance, metabolic capabilities, or pathogenic determinants. ICEs can also have negative impacts on their host cells. Here, we investigated the effects of the ICE (conjugative transposon) Tn916 on host cells. Because Tn916 is active in a relatively small subpopulation of host cells, we developed a fluorescent reporter system for monitoring activation of Tn916 in single cells. We found that when active in Bacillus subtilis and its natural host Enterococcus faecalis, Tn916 inhibited cell division and most cells died. We also observed these phenotypes on the population level in B. subtilis utilizing a modified version of Tn916 that can be activated in the majority of cells. We identified two genes (orf17 and orf16) in Tn916 that were sufficient to cause host growth defects and identified a single gene, yqaR, that is found in a defective phage (skin) in the B. subtilis chromosome that is required for this phenotype. However, these three genes are only partially responsible for the growth defect caused by Tn916, indicating that Tn916 possesses multiple mechanisms to affect growth and viability of host cells. These results highlight the complex relationships that conjugative elements have with their host cells and the interplay between mobile genetic elements.

show abstract

Determination of copy number and circularization ratio of Tn916-Tn1545 family of conjugative transposons in oral streptococci by droplet digital PCR

Cited by 6 publications

References 42 publications

Activation of the integrative and conjugative element Tn916 causes growth arrest and death of host bacteria

Activation of the integrative and conjugative element Tn916 causes growth arrest and death of host bacteria

Prevalence, diversity and transferability of the Tn916-Tn1545 family ICE in oral streptococci

Activation of the integrative and conjugative element Tn916causes growth arrest and death of host bacteria

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