Ancient RNA stems that terminate transcription

Area of Science:

• Molecular Biology
• Biochemistry
• Evolutionary Biology

Background:

• Multi-subunit RNA polymerases are crucial for transcription across all domains of life.
• While catalytic cores are conserved, transcription termination mechanisms appear to have diverged.
• Eukaryotic RNA polymerase III (pol III) utilizes RNA secondary structures for termination, similar to bacterial RNA polymerase.

Purpose of the Study:

• To explore the similarities and differences in RNA-dependent transcription termination mechanisms.
• To investigate the evolutionary origins of transcription termination.

Main Methods:

• Comparative analysis of transcription termination mechanisms in bacteria and eukaryotes (pol III).
• Examination of the role of RNA secondary structures in termination processes.

Main Results:

• RNA secondary structures are involved in termination by both bacterial RNA polymerase and eukaryotic pol III.
• The terminating RNA structures for pol III are formed by transcript bodies, not dedicated hairpins.
• These structures suggest a link to the ancient RNA-protein world.

Conclusions:

• RNA-dependent termination mechanisms likely predated the divergence of bacterial and archaeal/eukaryotic life.
• Transcription termination in eukaryotes (pol III) retains features reminiscent of early RNA-based processes.