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Large-scale Production of Recombinant RNAs on a Circular Scaffold Using a Viroid-derived System in Escherichia coli
Published on: November 30, 2018
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Viroids and Viroid-like Circular RNAs: Do They Descend from Primordial Replicators?
Benjamin D Lee1,2, Eugene V Koonin1
1National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
Life (Basel, Switzerland)
|January 21, 2022
Summary
Viroids are tiny infectious RNA molecules that replicate using a rolling circle mechanism. Their origin likely stems from mobile genetic elements, offering insights into early life evolution.
Area of Science:
- Virology
- Molecular Biology
- Evolutionary Biology
Background:
- Viroids are small, circular RNA pathogens lacking proteins, representing the smallest infectious agents.
- They replicate via rolling circle mechanism and are processed by ribozymes or host RNAses.
- Viroid-like RNAs include satellites of plant viruses and larger ribozyviruses like Hepatitis Delta Virus.
Purpose of the Study:
- To investigate the evolutionary origins of viroids.
- To challenge the hypothesis of viroids descending from primordial RNA replicators.
- To propose an alternative, more parsimonious evolutionary scenario for viroids.
Main Methods:
- Comparative analysis of viroid replication mechanisms.
- Examination of proposed evolutionary pathways from primordial RNA world.
- Evaluation of retrozymes as potential precursors to viroids.
Main Results:
- Viroids replicate using a rolling circle mechanism, producing multimeric intermediates.
- An alternative hypothesis suggests viroids evolved later from mobile genetic elements called retrozymes.
- Viroids and similar RNAs are minimal replicators, near the theoretical limit of size.
Conclusions:
- Viroids are unlikely direct descendants of primordial RNA replicators.
- The study of viroids provides insights into the emergence of replicators and early life evolution.
- Viroids serve as a paradigm for understanding the minimal requirements for life's emergence.
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