Partial tRNA deacylation specifically triggers Escherichia coli cell volume reduction

Area of Science:

• Microbiology
• Molecular Biology
• Cell Biology

Background:

• Cell growth involves complex regulation of cell division and volume.
• Transfer RNA (tRNA) acylation, the attachment of amino acids to tRNA, is crucial for protein synthesis.

Purpose of the Study:

• To investigate the role of tRNA acylation in regulating Escherichia coli cell volume.
• To determine if tRNA acylation is a critical sensing mechanism for cellular nutrient status.

Main Methods:

• Escherichia coli were subjected to continuous 366 nm illumination or specific tRNA acylation inhibitors.
• Thermosensitive mutants of aminoacyl-tRNA synthetases and tRNA (divE strain) were utilized.
• Cellular responses, including stringent and SOS responses, were analyzed in relation to cell volume changes.

Main Results:

• Limiting tRNA acylation by illumination or inhibitors caused cell volume reduction while maintaining division rate.
• In contrast, inhibitors of DNA replication, transcription, or other protein synthesis steps did not reduce cell volume.
• Mutants defective in tRNA acylation confirmed that limiting acylation triggers cell volume reduction.
• The stringent response modulated, but was not essential for, the volume reduction effect.
• SOS response masked the cell volume reduction.

Conclusions:

• Limitation of tRNA acylation is the primary trigger for cell volume reduction in Escherichia coli.
• tRNA acylation acts as a significant cellular sensor for changes in the nutrient environment.
• Cell volume regulation is distinct from cell division rate control and is influenced by nutrient availability via tRNA acylation.