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Christophe Zimmer @chzimmer.bsky.social · 10/09/2026

Work led by @danielkrentzel.bsky.social, together with @kelvinkho.bsky.social and Julienne Petit. Great collaboration with the labs of @ivo-boneca.bsky.social, @awehenkel.bsky.social and Mark Brönstrup, with help from the microscopy and screening platforms of @pasteur.fr

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Simonetta Gribaldo @sgribaldo.bsky.social · 23/09/2026

We are particularly proud of this work given the upcoming 50th anniversary of the discovery of Archaea in 1977 (same year Punk broke 😉) They continue to hold big surprises impacting all aspects of microbiology and evolution. Hope it'll encourage more young scientists to join this exciting field! 9/9

A free "archaeal" re-interpretation of the famous slogan "Punk's not dead", made by AI and just meant to be funny ;-)

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Simonetta Gribaldo @sgribaldo.bsky.social · 23/09/2026

A big shoutout to co-first authors robsmith93.bsky.social and @nikapende.bsky.social! Huge thanks to the whole EBMC team and the many colleagues who helped all along, and also our funders @agencerecherche.bsky.social; @frm-officiel.bsky.social; Fondation Bettencourt Schueller; @pasteur.fr 8/9

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Simonetta Gribaldo @sgribaldo.bsky.social · 23/09/2026

Building upon the legacy of Kandler and König, our findings reshape a 50-year-old view on archaeal PG structure. Given the importance of methanogens in ecology, biotechnology, and the animal&human microbiomes, these results open new avenues to study their biology and evolution 7/9 #ArchaeaSky

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Simonetta Gribaldo @sgribaldo.bsky.social · 23/09/2026

ArmA is conserved in all PG-bearing methanogens and beautifully localizes at the division site. Our deletion mutant confirms that this enzyme is required for cell division, hydrolysing archaeal PG to complete cytokinesis and cell separation 6/9

Epifluorescence microscopy showing ArmA localisation at the division site in Methanobrevibacter smithii at different stages of the cell cycle

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Simonetta Gribaldo @sgribaldo.bsky.social · 23/09/2026

Digestion of archaeal PG with ArmA and its analysis by NMR and LC-MS/MS reveals a new chemical structure ! It shows key novel features with respect to the current model, including a previously undescribed sugar that we name N-acetylarmosamine (ArmNAc) 5/9

The new structure of archaeal PG (left) as compared to the one by Kandler and Konig from the 70s (right)

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Simonetta Gribaldo @sgribaldo.bsky.social · 23/09/2026

Archaeal PG structure was characterized in the late 70s by pioneering work of Kandler and König on cell envelopes, which supported Woese’s proposal of Archaea as a third domain of life. It showed clear differences with bacterial PG, making it resistant to well-known enzymes (remember lysozyme?) 3/9

Three pioneers of the Archaea field. Carl Woese (left), Ralph Wolfe (middle) and Otto Kandler (right)
By Maya Kandler - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=69416862

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Simonetta Gribaldo @sgribaldo.bsky.social · 23/09/2026

While peptidoglycan (PG) is an essential and near-universal feature of Bacteria, it is largely absent in Archaea. A notable exception is a large clade of methane-producing archaea, which possess a cell wall with a distinct type of PG (also known as pseudomurein) 2/9

Scanning Electron Microscopy of Methanobrevibacter smithii, the main species of archaea from the human gut. Taken from https://doi.org/10.1016/j.tim.2025.10.003

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Simonetta Gribaldo @sgribaldo.bsky.social · 23/09/2026

Interested in #archaea, #methane, #cell-envelopes? New paper out @nature.com ! We discovered an enzyme that specifically cleaves the cell wall of methanogens, revealing a new chemical structure of archaeal peptidoglycan, 50 yrs after its first description www.nature.com/articles/s41... #MicroSky 🧵👇

nature.com

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Simonetta Gribaldo @sgribaldo.bsky.social · 23/09/2026

Our group teamed up with @ivo-boneca.bsky.social and Inaki Guijarro at the NMR facility @pasteur.fr to look at archaeal PG structure with modern approaches. Using a combination of bioinformatics, zymograms, and MS, we identified the first archaeal PG-cleaving glycosyl hydrolase that we name ArmA 4/9

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ivo-boneca.bsky.social @ivo-boneca.bsky.social · 08/04/2025

Easter is approaching but so is the abstract deadline for the Great Wall Symposium: May 1st! If you want a chance to present at the best conference, focused on the Bacterial Cell Envelope, crack on! thegreatwall-symposium.org Sicily, September 15-17th 2025

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