An experimental framework to assess biomolecular condensates in bacteria

Area of Science:

• Cell Biology
• Biophysics
• Microbiology

Background:

• High-resolution imaging of biomolecular condensates in living cells is crucial for linking in vitro observations to in vivo behavior.
• Studying bacterial biomolecular condensates is challenging due to inherent resolution limitations in bacterial systems.

Approach:

• Developed an experimental framework to probe the formation, reversibility, and dynamics of condensate-forming proteins in Escherichia coli.
• Utilized sub-micron scale imaging to observe condensate behavior within living bacterial cells.
• Employed the established marker IbpA (Inclusion body protein A) to differentiate between bacterial condensates and insoluble protein aggregates in vivo.

Key Points:

• Bacterial biomolecular condensates form above a critical concentration threshold and retain a soluble fraction.
• Condensates exhibit dynamic properties, including internal rearrangement and exchange between condensed and soluble phases.
• IbpA shows distinct colocalization patterns with condensates versus aggregates, serving as a reliable in vivo reporter.

Conclusions:

• The presented framework offers a generalizable, accessible, and rigorous method for investigating biomolecular condensates in bacteria at the sub-micron level.
• This research provides critical insights into the nature and behavior of bacterial condensates, bridging the gap between in vitro and in vivo studies.
• The findings enhance our understanding of cellular organization and protein aggregation in prokaryotic systems.