Intramolecular phenotypic capacitance in a modular RNA molecule.

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Biochemistry

Background:

• Phenotypic capacitance describes the genome's capacity to harbor hidden mutations, revealed by environmental or genetic shifts.
• Existing research on capacitance mechanisms primarily focuses on complex, multi-protein systems.
• Understanding capacitance in simpler systems like RNA is crucial for evolutionary insights.

Purpose of the Study:

• To demonstrate phenotypic capacitance in a single catalytic RNA molecule (ribozyme).
• To investigate the role of modularity in enabling capacitance within a ribozyme.
• To explore the influence of environmental conditions on mutation manifestation.

Main Methods:

• Utilized a naturally occurring modular ribozyme with scaffold and catalytic modules.
• Experimentally perturbed magnesium ion concentration to create a stressful environment.
• Employed in vitro selection and deep sequencing to identify genotypes with altered catalytic activity.

Main Results:

• Identified conditional mutations affecting ribozyme phenotype under low magnesium conditions.
• These mutations preserved the wild-type phenotype under normal magnesium concentrations.
• The observed conditional buffering was localized to the scaffold module, impacting catalytic activity.

Conclusions:

• Demonstrated phenotypic capacitance within a single RNA molecule, challenging previous complexity assumptions.
• Highlighted the role of modularity in facilitating capacitance and buffering phenotypes.
• Suggests that phenotypic capacitance in RNA may have played a significant role since the origin of life.