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Viroids: survivors from the RNA world?
Ricardo Flores1, Selma Gago-Zachert, Pedro Serra
1Instituto de Biología Molecular y Celular de Plantas (UPV-CSIC), 46022 València, Spain;
Annual Review of Microbiology
|July 9, 2014
Summary
Viroids exhibit characteristics of primitive RNA replicons, suggesting they may be relics of the RNA world. Their properties, like small size and high G+C content, support this RNA world hypothesis.
Area of Science:
- Origin of life studies
- Molecular biology
- Virology
Background:
- The RNA world hypothesis posits that RNA preceded DNA and proteins as the primary carrier of genetic information and catalytic activity.
- Relics of this early RNA-dominated era may exist in modern biological systems.
Purpose of the Study:
- To identify potential survivors of the RNA world and examine their characteristics.
- To evaluate viroids as candidates for relics of the RNA world.
Main Methods:
- Comparative analysis of viroid properties against expected characteristics of primitive RNA replicons.
- Examination of structural and functional attributes of viroids.
Main Results:
- Viroids possess several key properties aligning with primitive RNA replicons: small size, high G+C content for fidelity, circular structure for complete replication, structural periodicity for genome expansion, lack of protein-coding ability, and ribozyme-mediated replication.
- These features suggest viroids could be evolutionary descendants of RNA world entities.
Conclusions:
- Viroids display compelling evidence supporting their role as survivors from the RNA world.
- The properties of viroids provide insights into the transition from an RNA-centric to a DNA- and protein-centric biological system.
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