Can the Origin of the Genetic Code Be Explained by Direct RNA Templating?

Motivated by the RNA world hypothesis, Michael Yarus and colleagues have proposed a model for the origin of the ‘universal’ genetic code, in which RNA aptamers directly template amino acids for protein assembly. Yarus et al. claim that this “direct RNA templating” (DRT) model provides a stereochemical basis for the origin of the code, as shown by the higher-thanexpected frequency of cognate coding triplets in aptamer amino acid-binding sites. However, the DRT model suffers from several defects. These include the selective use of data, incorrect null models, a weak signal even from positive results, an implausible geometry for the primordial RNA template (in relation to the universally-conserved structures of modern ribosomes), and unsupported assumptions about the pre-biotic availability of amino acids. Although Yarus et al. claim that the DRT model undermines an intelligent design explanation for the origin of the genetic code, the model’s many shortcomings in fact illustrate the insufficiency of undirected chemistry to construct the semantic system represented by the code we see today. Cite as: Meyer SC, Nelson PA (2011) Can the origin of the genetic code be explained by direct DNA templating? BIO-Complexity 2011(2): 1-10. doi:10.5048/BIO-C.2011.2 Editor: Peter Imming Received: March 23, 2011; Accepted: August 5, 2011; Published: August 24, 2011 Copyright: © 2011 Meyer, Nelson. This open-access article is published under the terms of the Creative Commons Attribution License, which permits free distribution and reuse in derivative works provided the original author(s) and source are credited. Notes: A Critique of this paper, when available, will be assigned doi:10.5048/BIO-C.2011.2.c. * Email: [email protected]