Ribosomal precursor particles of Bacillus megaterium

Area of Science:

• Molecular Biology
• Microbiology
• Biochemistry

Background:

• Understanding bacterial ribosome biogenesis is crucial for cellular function.
• Ribonucleoprotein (RNP) particles are key intermediates in ribosome assembly.
• Previous studies have identified precursor ribosomal subunits, but their in vivo forms remain under investigation.

Purpose of the Study:

• To characterize the in vivo structure of precursor ribosomal subunits in Bacillus megaterium.
• To investigate the influence of cell disruption methods on the observed precursor RNP particle profiles.

Main Methods:

• Pulse-labeling of Bacillus megaterium cells followed by protoplast formation.
• Analysis of protoplast lysates using sucrose gradient sedimentation.
• Polyacrylamide gel electrophoresis (PAGE) of ribosomal ribonucleic acid (rRNA) from isolated RNP particles.
• Comparison of sedimentation profiles after deoxycholate treatment or French press cell lysis.

Main Results:

• Sucrose gradient sedimentation revealed predominantly 50S and 30S precursor RNP particles in intact protoplast lysates.
• PAGE confirmed the precursor nature of these particles, containing 23S and 16S rRNA, respectively.
• Deoxycholate treatment or French press lysis altered the profile, diminishing 50S particles and increasing slower sedimenting species (e.g., 43S), suggesting particle breakdown or conformational changes.

Conclusions:

• The native in vivo forms of Bacillus megaterium precursor ribosomal subunits are likely 50S and 30S RNP particles.
• Cell disruption techniques, including detergent treatment and mechanical lysis, can artifactually alter the observed size and composition of precursor RNP particles.
• These findings highlight the importance of gentle cell lysis methods for accurately studying ribosome biogenesis intermediates.