Ordered processing of Escherichia coli 23S rRNA in vitro

Area of Science:

• Molecular Biology
• Microbiology
• Biochemistry

Background:

• 23S precursor ribosomal RNA (pre-rRNA) processing is crucial for ribosome biogenesis.
• RNase III deficiency in E. coli leads to unprocessed 23S pre-rRNA accumulation in ribosomes.

Purpose of the Study:

• To investigate the in vitro processing pathway of 23S rRNA.
• To elucidate the roles of RNase III and other enzymes in rRNA maturation.
• To explore the coordination between rRNA processing and translation.

Main Methods:

• Utilized RNase III-deficient E. coli strains for substrate preparation.
• Employed in vitro processing reactions with 50S ribosomes.
• Analyzed processing products using S1 nuclease protection assays.

Main Results:

• Demonstrated an ordered 23S rRNA processing pathway.
• Identified RNase III as an initiator cleaving the double-stranded stem into intermediates.
• Showed that mature termini are generated by other enzymes, with 3' end maturation being exonucleolytic.
• Observed coordination between 5' end cleavage and 3' end maturation.
• Found that mature termini formation is efficient with protein synthesis additives.
• Detected processing intermediates in polysomes, suggesting a link to translation.

Conclusions:

• 23S rRNA processing is an ordered, multi-step pathway initiated by RNase III.
• Post-RNase III maturation involves other enzymes and is coordinated with translation.
• The findings provide insights into the intricate regulation of ribosome biogenesis.