The origin of the genetic code is encrypted in the structure of present-day transfer RNAs
TLDR
Present-day tRNA structures from Bacillus subtilis provide a genealogical tree that encrypts the evolutionary timeline of the genetic code.
Key contributions
- Compared Bacillus subtilis tRNA primary structures to construct a genealogical tree.
- The tRNA tree reveals the evolutionary timeline of amino acid entry into the Universal Codon Table.
- Proposes that tRNAs were a major component in the formation of the genetic code.
- Introduces the "poly-tRNA theory" as a general framework for genetic code origin.
Why it matters
This paper offers a novel theory, the poly-tRNA theory, for the origin of the genetic code, a long-standing mystery. By analyzing tRNA structures, it provides a concrete, data-driven scenario for how amino acids colonized the codon table, shedding light on life's earliest molecular evolution.
Original Abstract
Background/ Objectives: Resolving the origin of the genetic code is fundamental to understanding how life began its journey out of the chemical world. Since its deciphering some 60 years ago, there is still no general theory of the emergence of the genetic code. My objectives are to bring some unique data that might provide some insight into this particular issue. Methods: Because tRNA (transfer RNA) constitutes a crucial piece of the present translational system, having unique structural characteristics, I hypothesized that they might constitute the key elements at the origin of the genetic code and thus decided to compare the primary structure of the tRNAs from a bacterium, Bacillus subtilis. Results: The comparison of the primary structure of the tRNAs from Bacillus subtilis generated a genealogical tree, meaning that the tRNAs were all related and appeared gradually in a precise time sequence. Remarkably, analysis of the various characteristics of this tRNAs tree showed that it very likely reflects the time of entry of amino acids into the Universal Codon Table. Conclusions: These results strongly suggest that the tRNA entity was indeed a major component in the formation of the genetic code and, further, provide a likely scenario for the time sequence of codon colonization of the Universal Codon Table by the various amino acids at the very beginning of life. Also, these data are interpreted in terms of a general theory of the origin of the genetic code I propose, the poly-tRNA theory.
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