Sprecher
Beschreibung
Dina Grohmann
Recent research has established archaea as the closest known relatives of eukaryotes and thus central to understanding the origin of complex life. Often thriving in extreme or chemically unusual environments, archaea provide insight into how life persists under conditions resembling early Earth [1,2] and how the first complex cellular systems may have evolved. In this talk, I focus on two molecular aspects that illuminate this transition.
(1) The rRNA modification landscape of hyperthermophilic archaea:
Systematic comparison of hyperthermophilic and mesophilic archaea with bacteria and eukaryotes revealed that nearly 50% of RNA modifications in extreme hyperthermophiles are temperature‑dependent and induced at high temperatures via temperature‑regulated enzymes. These rRNA modifications are required for growth at elevated temperatures, and cryo‑EM analyses of ribosomes from wild‑type and enzyme‑deficient strains show that they stabilize ribosomal structure through recurrent interactions [3]. Together, dynamic rRNA modifications are a key contributor to robust information processing in extreme environments and suggest a potential role in RNA‑world chemistry on early Earth.
(2) Unique archaeal membrane chemistry and behaviour:
Archaeal membranes are built from ether lipids, fundamentally distinct from the ester lipids of bacteria and eukaryotes. In hyperthermophiles, membrane‑spanning tetraether lipids support survival at extreme temperatures. Yet, the biophysical properties of archaeal membranes have remained poorly understood. We characterized the lipid compositions of four hyperthermophilic archaea and established them as in vitro model membranes. Their composition governs membrane fluidity and phase behavior and strongly differentiates archaeal membranes from bacterial ones. We further observed a tendency for archaeal giant unilamellar vesicles to form tubular and multilamellar structures, pointing to a high capacity for membrane remodelling and adaptation. These in vitro findings are supported by in vivo data: for one of the model archaea, we discovered an unusual cell‑division cycle, in which an ESCRT‑III cytokinetic ring repeatedly constricts the inner membrane to generate multiple daughter cells within a shared periplasm; the outer membrane then ruptures, releasing daughters that reestablish the parental architecture through membrane duplication.
Together, these findings suggest that archaea may have provided molecular innovations that helped pave the way for the emergence of complex life.
References:
1. Helmbrecht V, Reichelt R, Grohmann D, Orsi WD. Simulated early Earth geochemistry fuels a hydrogen-dependent primordial metabolism. Nat Ecol Evol. 2025, doi: 10.1038/s41559-025-02676-w.
2. Grünberger F, Schmid G, El Ahmad Z, Fenk M, Vogl K, Reichelt R, Hausner W, Urlaub H, Lenz C, Grohmann D. Uncovering the temporal dynamics and regulatory networks of thermal stress response in a hyperthermophile using transcriptomics and proteomics. mBio. 2023. doi: 10.1128/mbio.02174-23.
3. Garcia-Campos MA, Georgeson J, Nir R, Reichelt R, Fluke KA, Matzov D, Iyer V, Burkhart BW, Lui L, Kustanovich A, Grünberger F, Gamage ST, Howpay S, Gerovac M, Alexandre N, Nobe Y, Nowak YS, Glatt S, Jona G, Ferreira-Cerca S, Vogel J, Taoka M, Meier J, Westhof E, Santangelo TJ, Grohmann D, Shalev-Benami M#, Schwartz S# . Pan-modification profiling facilitates a cross-evolutionary dissection of the thermoregulated ribosomal epitranscriptome. Cell. 2025. doi: 10.1016/j.cell.2025.09.014