Bacteria DNA Conjugation: from The Cellular to The Community Level

Virolle, Chloé; Goldlust, Kelly; Djermoun, Sarah; Bigot, Sarah; Lesterlin, Christian

doi:10.20944/preprints202009.0405.v1

Cited by 29 publications

(1 citation statement)

References 282 publications

(375 reference statements)

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“…The transfer of the PCR target regions used in detecting FRNAPH genogroups (RNA replicases, maturase, capsid, or assembly genes) through the F-plasmid may confound quantification of FRNAPH genogroups, especially as a single bacterium is likely to contain numerous copies of the plasmid. For example, F + coliphages may multiply in coliforms, including not only E. coli but also Salmonella, Shigella, Bacteroides, Caulobacter, Pseudomonas, and Acinetobacter providing an appropriate pili expressed on the bacterial surface (Leclerc et al, 2000;Cann, 2001;Virolle et al, 2020). The fragments of genetic material may be transferred along with F-plasmid, resulting in horizontal gene transfer, thereby transmitting genes (pathogenicity, metabolic properties, or antimicrobial resistance linked) among the bacteria across the water distribution network (Maganha de Almeida Kumlien et al, 2021).…”

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Coliphages as viral indicators of sanitary significance for drinking water

2022

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Coliphages are virus that infect coliform bacteria and are used in aquatic systems for risk assessment for human enteric viruses. This mini-review appraises the types and sources of coliphage and their fate and behavior in source waters and engineered drinking water treatment systems. Somatic (cell wall infection) and F+ (male specific) coliphages are abundant in drinking water sources and are used as indicators of fecal contamination. Coliphage abundances do not consistently correlate to human enteric virus abundance, but they suitably reflect the risks of exposure to human enteric viruses. Coliphages have highly variable surface characteristics with respect to morphology, size, charge, isoelectric point, and hydrophobicity which together interact to govern partitioning and removal characteristics during water treatment. The groups somatic and F+ coliphages are valuable for investigating the virus elimination during water treatment steps and as indicators for viral water quality assessment. Strain level analyses (e.g., Qβ or GA-like) provide more information about specific sources of viral pollution but are impractical for routine monitoring. Consistent links between rapid online monitoring tools (e.g., turbidity, particle counters, and flow cytometry) and phages in drinking water have yet to be established but are recommended as a future area of research activity. This could enable the real-time monitoring of virus and improve the process understanding during transient operational events. Exciting future prospects for the use of coliphages in aquatic microbiology are also discussed based on current scientific evidence and practical needs.

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Coliphages as viral indicators of sanitary significance for drinking water

2022

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CRISPR-Cas12a targeting of ssDNA plays no detectable role in immunity

Marino

Pinilla‐Redondo

Bondy‐Denomy

2022

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CRISPR-Cas12a (Cpf1) is a bacterial RNA-guided nuclease that cuts double-stranded DNA (dsDNA) at sites specified by a CRISPR RNA (crRNA) guide. Additional activities have been ascribed to this enzyme in vitro: site-specific (cis) single-stranded DNA (ssDNA) cleavage and indiscriminate (trans) degradation of ssDNA, RNA, and dsDNA after activation by a complementary target. The ability of Cas12a to cleave nucleic acids indiscriminately has been harnessed for many applications, including diagnostics, but it remains unknown if it contributes to bacterial immunity. Here, we provide evidence that cleavage of ssDNA in cis or in trans by Cas12a is insufficient to impact immunity. Using LbCas12a expressed in either Pseudomonas aeruginosa or Escherichia coli, we observed that cleavage of dsDNA targets did not elicit cell death or dormancy, suggesting insignificant levels of collateral damage against host RNA or DNA. Canonical immunity against invasive dsDNA also had no impact on the replicative fitness of co-infecting ssDNA phage or plasmid in trans. Lastly, crRNAs complementary to invasive ssDNA did not provide protection, suggesting that ssDNA cleavage does not occur in vivo or is insignificant. Overall, these results suggest that CRISPR-Cas12a immunity predominantly occurs via canonical targeting of dsDNA, and that the other activities are in vitro irregularities.

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Real time visualisation of conjugation reveals the molecular strategy evolved by the conjugative F plasmid to ensure the sequential production of plasmid factors during establishment in the new host cell

Couturier

Virolle

Goldlust

et al. 2022

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DNA conjugation is a contact-dependent horizontal gene transfer mechanism responsible for disseminating drug resistance among bacterial species. Conjugation remains poorly characterised at the cellular scale, particularly regarding the reactions occurring after the plasmid enters the new host cell. Here, we use live-cell microscopy to visualise the intracellular dynamics of conjugation in real time. We reveal that the transfer of the plasmid in single-stranded DNA (ssDNA) form followed by its conversion into double-stranded DNA (dsDNA) are fast and efficient processes that occur with specific timing and subcellular localisation. Notably, the ss-to-dsDNA conversion is the critical step that governs the timing of plasmid-encoded protein production. The leading region that first enters the recipient cell carries single-stranded promoters that allow the early and transient synthesis of leading proteins immediately upon entry of the ssDNA plasmid. The subsequent ss-to-dsDNA conversion turns off leading gene expression and licences the expression of the other plasmid genes under the control of conventional double-stranded promoters. This elegant molecular strategy evolved by the conjugative plasmid allows for the timely production of factors sequentially involved in establishing, maintaining and disseminating the plasmid.

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Bacteria DNA Conjugation: from The Cellular to The Community Level

Cited by 29 publications

References 282 publications

Coliphages as viral indicators of sanitary significance for drinking water

Coliphages as viral indicators of sanitary significance for drinking water

CRISPR-Cas12a targeting of ssDNA plays no detectable role in immunity

Real time visualisation of conjugation reveals the molecular strategy evolved by the conjugative F plasmid to ensure the sequential production of plasmid factors during establishment in the new host cell

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