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Accession Number ADA571093
Title Thermodynamic Basis for the Emergence of Genomes during Prebiotic Evolution.
Publication Date May 2012
Media Count 20p
Personal Author H. Woo J. Reifman R. V. Satya
Abstract The RNA world hypothesis views modern organisms as descendants of RNA molecules. The earliest RNA molecules must have been random sequences, from which the first genomes that coded for polymerase ribozymes emerged. The quasispecies theory by Eigen predicts the existence of an error threshold limiting genomic stability during such transitions but does not address the spontaneity of changes. Following a recent theoretical approach, we applied the quasispecies theory combined with kinetic/thermodynamic descriptions of RNA replication to analyze the collective behavior of RNA replicators based on known experimental kinetics data. We find that, with increasing fidelity (relative rate of base-extension for Watson-Crick versus mismatched base pairs), replications without enzymes, with ribozymes, and with protein-based polymerases are above, near, and below a critical point, respectively. The prebiotic evolution therefore must have crossed this critical region. Over large regions of the phase diagram, fitness increases with increasing fidelity, biasing random drifts in sequence space toward 'crystallization.' This region encloses the experimental nonenzymatic fidelity value, favoring evolutions toward polymerase sequences with ever higher fidelity, despite error rates above the error catastrophe threshold. Our work shows that experimentally characterized kinetics and thermodynamics of RNA replication allow us to determine the physicochemical conditions required for the spontaneous crystallization of biological information. Our findings also suggest that among many potential oligomers capable of templated replication, RNAs may have evolved to form prebiotic genomes due to the value of their nonenzymatic fidelity.
Keywords Behavior
Experimental data
Phase diagrams
Physicochemical properties
Prebiotic evolution
Ribonucleic acids
Threshold effects

Source Agency Non Paid ADAS
NTIS Subject Category 57E - Clinical Medicine
57F - Cytology, Genetics, & Molecular Biology
99F - Physical & Theoretical Chemistry
Corporate Author Army Medical Research and Materiel Command (Provisional), Fort Detrick, MD. Telemedicine and Advanced Tech Research Center.
Document Type Journal article
Title Note Journal article.
NTIS Issue Number 1315
Contract Number N/A

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