Coevolution Theory of the Genetic Code at Age Forty: Pathway to Translation and Synthetic Life

Abstract

The origins of the components of genetic coding are examined in the present study. Genetic information arose from replicator induction by metabolite in accordance with the metabolic expansion law. Messenger RNA and transfer RNA stemmed from a template for binding the aminoacyl-RNA synthetase ribozymes employed to synthesize peptide prosthetic groups on RNAs in the Peptidated RNA World. Coevolution of the genetic code with amino acid biosynthesis generated tRNA paralogs that identify a last universal common ancestor (LUCA) of extant life close to Methanopyrus, which in turn points to archaeal tRNA introns as the most primitive introns and the anticodon usage of Methanopyrus as an ancient mode of wobble. The prediction of the coevolution theory of the genetic code that the code should be a mutable code has led to the isolation of optional and mandatory synthetic life forms with altered protein alphabets.

Frozen Accident Pushing 50: Stereochemistry, Expansion and Chance in the Evolution of the Genetic Code

“…In contrast, the coevolution model, although producing some level of error minimization, was substantially inferior to the other scenarios, as also demonstrated in an earlier analysis by Higgs [79]. These findings cast doubt on the direct relevance of coevolution model [57,59] and imply that, although substantial error minimization is a key property of the SGC, this feature likely evolved as a by-product of code expansion rather than by direct selection for code robustness.…”

“…Massey explored three distinct scenarios of the code expansion: the "2-1-3" model [78], which is similar to expansion schemes independently proposed by Higgs [79] and Francis [80], the ambiguity reduction model [81] and precursor-product scenario specified by the coevolution theory [57,59]. The 2-1-3 model and similar schemes posit that the code started from an ancestral stage, in which only the second base of the codon was informative, and expanded by assigning specificity to the first, and then, in some codon series, the third bases (another idea that goes back to Crick's 1968 paper).…”

“…The second theory, known as coevolution, holds that the genetic code is shaped by the precursor-product relationships between amino acids [57][58][59][60]. Under the coevolution scenario, the code evolved from an ancestral version that included only the simple amino acids that can be produced abiogenically (see next section) by expanding to incorporate the more complex amino acids, in parallel with the evolution of the respective biosynthetic pathways (hence coevolution -between the code and the amino acid biosynthesis pathways).…”

Self-Referential Encoding on Modules of Anticodon Pairs—Roots of the Biological Flow System

“…The chronology offered by the self-referential model clashes with the traditional studies on the origins of the code [69][70][71][72][73][74][75][76][77][78]. These are centered on the set of amino acids that are produced in relative abundance under prebiotic conditions, possibly representing what would be expected from early Earth geochemical systems.…”

“…Even the coevolution hypothesis, saying that much of the code organization is derived from amino acid biosynthesis pathways, starts with the geochemical set [70,71,78]. This is centered on the amino acids in the 3'C row of the matrix Val Ala Gly Asp, which could also profit from high stability of some triplet pairs such as codons Ala-GCC:GGC-Gly, less so in Val-GUC:GAC-Asp.…”