Abstracts (Kopie)
Short talk 3: Frosty Foci - The E. coli DEAD-box ATPase CsdA forms nucleoid-associated foci at cold temperature
Maria Hondele
University of Basel, Biozentrum, Spitalstrasse 41, 4056 Basel [CH], maria.hondele@unibas.ch
Author(s):
Michelle Jennifer Gut, Ruta Prakapaité, Alexia Loynton-Ferrand, Alexander Schmidt, Maria Hondele
Subcellular organization is essential for maintaining cellular homeostasis. Unlike eukaryotic cells, bacteria lack membranebound organelles and instead rely on alternative structures, including biomolecular condensates.
In eukaryotes, DEAD-box ATPases (DDXs) play crucial roles in many steps of RNA processing and have emerged as important regulators of condensate formation. Intriguingly, we found that three of the five E. coli DDXs form condensates in vitro, suggesting that bacteria also employ DDX-mediated condensation for cellular organization.
Of the E. coli DDXs, the ribosome biogenesis factor CsdA showed the highest condensation propensity and is the only DDX essential for growth at cold temperatures. Truncation studies indicated that CsdA condensation correlates with ATPase activity and influences growth at low temperatures.
Quantitative mass spectrometry showed that cold temperature significantly induces CsdA expression, raising its cellular concentration above its in vitro condensation threshold. Intriguingly, super-resolution microscopy revealed that endogenous CsdA forms prominent clusters in close proximity to the nucleoid, and that condensation-deficient mutants fail to form these foci.
Our data suggest that at low temperatures, CsdA clusters promote ribosome biogenesis. This function is reminisent of the eukaryotic nucleolus, a hierarchically organized condensate containing multiple DDXs, hinting at an evolutionarily conserved mechanism for ribosomal RNA processing.