Related Experiment Videos
Real ribozymes suggest a relaxed error threshold.
Adám Kun1, Mauro Santos, Eörs Szathmáry
1Collegium Budapest, Institute for Advanced Study, Szentháromság u. 2. Budapest H-1014, Hungary.
Nature Genetics
|August 30, 2005
Summary
Replication fidelity significantly impacts genome length. Improved accuracy in RNA replication allows for larger genomes, supporting complex molecular systems like riboorganisms.
Area of Science:
- Molecular Biology
- Origin of Life Studies
- Genomics
Background:
- Replication fidelity is a key constraint on genome size in early life.
- The error threshold limits the length of genomes maintainable by selection.
- Early replicators are presumed to have been short due to error-prone replication.
Purpose of the Study:
- To investigate the phenotypic error threshold in RNA replication.
- To determine the potential genome size supportable by selection under specific fidelity conditions.
- To assess the implications for the emergence of complex early life forms.
Main Methods:
- Comparative analysis of two extensively mutagenized ribozymes.
- Experimental determination of copying fidelity and its effect on the phenotypic error threshold.
- Modeling of genome size maintenance based on observed fidelity.
Main Results:
- A copying fidelity of 0.999 per digit per replication raises the phenotypic error threshold above 7,000 nucleotides.
- This fidelity permits the selective maintenance of a riboorganism with a genome exceeding 100 genes.
- The required accuracy is an order of magnitude greater than current in vitro-generated polymerase ribozymes.
Conclusions:
- The error threshold is sensitive to the fitness landscape, allowing for larger genomes in an RNA world.
- A genome size comparable to tRNA is achievable with sufficient replication accuracy.
- This finding has significant implications for understanding the evolution of early cellular life and the potential for complex molecular systems.