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Posts by Calum H. G. Johnston

PREreview of “The broad-spectrum RumC1 bacteriocin targets a transient peptidoglycan intermediate of the nascent cell wall” Authored by Alizée Malnoë and 5 other authors

Here’s our second @iubiology.bsky.social public review of the semester! #PreprintReview via
@prereview.bsky.social
@asapbio.bsky.social
Looking forward to discussion 🧫 🔬
@polardlab.bsky.social
@chgjohnston.bsky.social
& all authors! #Microsky #Streptococcus
prereview.org/reviews/1963...

4 days ago 7 2 0 0
Advancing microbiology through foundational science - Nature Microbiology Microorganisms have tremendous potential to impact humanity, but such revelations are only possible in the light of foundational, discovery-based microbiology research.

A welcome editorial message.

www.nature.com/articles/s41...

1 week ago 21 10 1 0

Pleased to share a collaorative study into the mode of action of the novel bacteriocin RumC1 - led in the lab by Anne Boyeldieu. This study reveals that RumC1 targets nascent peptidoglycan to kill monoderm bacteria.

www.biorxiv.org/content/10.6...

1 month ago 2 2 0 0

Great talk from @nfrk92.bsky.social (from the TacC lab) at the CBI today, telling us about the mechanisms behind early expression of leading strand genes during conjugation. Cool work!

1 month ago 1 0 0 0
Two D-loop resolution systems enable natural genetic transformation in bacteria Natural transformation is a widespread mechanism driving genetic exchanges in bacteria. It proceeds by the capture and internalization of exogenous DNA in linear single strands, ultimately integrated in the genome by homologous recombination. It is unknown how the RecA-directed D-loop intermediate of this dedicated recombination pathway is processed. We report that resolution of the transformation D-loop depends on two endonucleases of opposing phylogenetic distribution in bacteria. One is YraN, which has co-evolved and interacts with the ComM helicase, known to extend DNA recombination at the transformation D-loop. The other is CoiA, which is restricted to the Bacillota. CoiA is shown to be a resolvase of the transformation D-loop, extended by the RadA helicase in these species. We demonstrate that both YraN and CoiA act synergistically with their cognate helicases. These findings reveal that bacteria have evolved two helicase/nuclease pairs for the maturation and recombination extension of the transformation D-loop. ### Competing Interest Statement The authors have declared no competing interest. Agence Nationale de la Recherche, https://ror.org/00rbzpz17, ANR-20-CE12-0004, ANR-10-BLAN-1331, ANR-17-CE13-0031, ANR-22-CE44-0044, ANR-10-LABX-62-IBEID, PIA/ANR-16-CONV-0005 Fondation pour la Recherche Médicale, https://ror.org/04w6kn183, FDT202001010890 European Union's Horizon research and innovation programme. Marie Skłodowska-Curie Postdoctoral Fellowships, 101208987 National Institute of Health, USA, R35GM128674

#microsky
Massive update of preprint with @polardlab.bsky.social!
Bacteria have evolved two systems to recombine extracellular DNA
www.biorxiv.org/content/10.1...
Kudos to lead authors Léo Hardy, Violette Morales and Clothilde Rousseau, and to outstanding Dalia's lab and @epcrocha.bsky.social
🧵⬇️

3 months ago 18 8 1 0
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A toxin/antitoxin system targeting the replication sliding-clamp induces competence in Streptococcus pneumoniae Author summary The environment in which bacteria live puts them under a great deal of stress, forcing them to adapt constantly, either temporarily or permanently. Streptococcus pneumoniae, a pathogeni...

Delighted to share a new paper from our lab, a study led by Mathieu Bergé looking at how an endogenous toxin targets replication to induce competence in the pneumococcus. dx.plos.org/10.1371/jour...

3 months ago 15 10 1 1
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Rescuing the bacterial replisome at a nick requires recombinational repair and helicase reloading - Nature Communications DNA damage can lead to cell death. Here, the authors show that a simple cut on either strand of DNA can inactivate bacterial chromosome replication. Surprisingly, only a core set of recombination prot...

A cool genetic system to study site-pecific replication fork collapse and repair from the brilliant @winterhalterlab.bsky.social

www.nature.com/articles/s41...

3 months ago 28 9 0 2
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New pub. from the lab !

We discovered that potato tubers exert intense selective pressure during Dickeya solani infection, driving the rapid emergence of mutations in the sRNA ArcZ. These mutations lead to the appearance of "social cheaters" that sweep through the pop. in as few as 30 generations.

3 months ago 7 2 1 0
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UK to rejoin EU’s Erasmus student exchange programme Exclusive: British students will be able to participate in EU-wide scheme from January 2027, sources say

Great news! 🎊

www.theguardian.com/world/2025/d...

4 months ago 8 2 0 0
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Le CNRS s’émancipe du Web of Science À partir du 1er janvier 2026, le CNRS coupera l’accès à l’une des plus importantes bases bibliométriques commerciales : le

Le 1er janvier 2026, le CNRS coupera l’accès au Web of Science, Core Collection et Journal Citation Reports. Une nouvelle étape de sa politique en faveur de la science ouverte pour promouvoir des alternatives ouvertes, transparentes et responsables.

4 months ago 93 53 3 3
Rescuing the bacterial replisome at a nick requires recombinational repair and helicase reloading - Nature Communications DNA damage can lead to cell death. Here, the authors show that a simple cut on either strand of DNA can inactivate bacterial chromosome replication. Surprisingly, only a core set of recombination prot...

Cool work from Heath Murray's lab where they use Cas9 nickase to study how ssDNA breaks are repaired in Bacillus subtilis #MicroSky www.nature.com/articles/s41...

4 months ago 16 8 0 1

New paper alert 🚨
I am super happy about it, for many reasons!
👥 It was a great collaborative project with Calum @chgjohnston.bsky.social and J. Pablo Radicella, designed a long time ago (in the pre-AlphaFold era - can you imagine?) together with @polardlab.bsky.social and @raphguerois.bsky.social

4 months ago 14 7 2 0

Thanks Eric! 🙂

4 months ago 0 0 0 0

Thanks Xavier! :)

4 months ago 1 0 0 0

Congratulations, really nice work!

4 months ago 1 0 0 0
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A tripartite protein complex promotes DNA transport during natural transformation in Firmicutes | PNAS Natural genetic transformation is a conserved mechanism of bacterial horizontal gene transfer, which is directed entirely by the recipient cell and...

Pleased to share our recent article in PNAS - a collaboration with @jessicaandreani.bsky.social & Pablo Radicella, with important roles played by many members of each team.

A tripartite protein complex promotes DNA transport during natural transformation in Firmicutes www.pnas.org/doi/10.1073/...

4 months ago 37 15 2 3
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Thanks for the kind words Rémi! :)

4 months ago 1 0 0 0
University of Glasgow - Postgraduate study - Centres for Doctoral Training - NorthWest Biosciences - Our Projects - Underpinning Bioscience - Paul A Hoskisson

Come and work with me and @ariannebabina.bsky.social on #Streptomyces evolution and antibiotic production

Origins of a tangled bank: Adaptation and evolution in antibiotic-producing Streptomyces

www.gla.ac.uk/postgraduate...

please repost

6 months ago 36 56 0 3

New paper from our lab up on Biorxiv, showing how a toxin targets replication to induce competence. 👇

7 months ago 2 3 0 0
Elucider le rôle des messagers secondaires (p)ppGpp et c-di-GMP dans la coordination des réponses bactériennes au stress et à l'adhésion à une surface // Decoding the role of intracellular messengers ... Comprendre comment les bactéries modulent leur croissance face à des changements environnementaux est essentiel pour développer de nouvelles stratégies de lutte contre les infections. Dans notre labo...

Offre de thèse disponible dans notre équipe au @mmsb-lyon.bsky.social
Si vous êtes étudiant(e) en Master 2 et intéressé(e) par la génétique bactérienne, microscopie à épifluorescence et biochimie, contactez-nous et postulez à l'offre!
Dossier pour le 13/06
Concours école doctorale E2M2: 8 et 9/07.

10 months ago 4 10 0 0
6th Zoom on Griffiths Legacy - 2025 - Sciencesconf.org

For those who are interested in all things 'transformation', here is a link to registration for the 6th edition of the Zoom on Griffith's Legacy, the 4th and 5th June 2025.

griffiths2025.sciencesconf.org

It has been fun co-organising this with Luisa Hiller. We hope to see you there!

11 months ago 0 0 0 0
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A tripartite protein complex promotes DNA transport during natural transformation in firmicutes. Natural genetic transformation is a conserved mechanism of bacterial horizontal gene transfer, which is directed entirely by the recipient cell and facilitates the acquisition of new genetic traits su...

Pleased to share a new preprint - a great collaboration with @jessicaandreani.bsky.social and the Guerois lab at I2BC, and the Radicella lab at the CEA. Using stuctural modelling, we reveal & validate a 3 protein complex involved in DNA import during transformation.

www.biorxiv.org/content/10.1...

11 months ago 14 8 0 1
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Let's start the Bsky adventure with a job post. Still about two weeks to apply to this postdoc position on "Molecular and Structural Biology of Membrane Biogenesis" in the labs @raffaeleieva.bsky.social ky.social and @fronzeslab.bsky.social slab.bsky.social in beautiful south-west of France!

1 year ago 11 21 1 2
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Competence induction of homologous recombination genes protects pneumococcal cells from genotoxic stress | mBio Homologous recombination (HR) is a mechanism of DNA strand exchange important for both the maintenance and plasticity of bacterial genomes. Bacterial HR is driven by the recombinase RecA along with ma...

Really proud of our new paper, my first as last author. We explored the importance of homologous recombination genes in transformation and genotoxic stress tolerance during competence. Give it a read/like! 🙂

journals.asm.org/doi/10.1128/...

1 year ago 17 5 2 1
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