Metabolic Basis for the Self-Referential Genetic Code |
| |
Authors: | Romeu Cardoso Guimarães |
| |
Institution: | 1.Lab. Biodiversidade e Evolu??o Molecular, Dept. Biologia Geral, Inst. Ciências Biológicas,Univ. Federal de Minas Gerais,Belo Horizonte,Brazil |
| |
Abstract: | An investigation of the biosynthesis pathways producing glycine and serine was necessary to clarify an apparent inconsistency
between the self-referential model (SRM) for the formation of the genetic code and the model of coevolution of encodings and
of amino acid biosynthesis routes. According to the SRM proposal, glycine was the first amino acid encoded, followed by serine.
The coevolution model does not state precisely which the first encodings were, only presenting a list of about ten early assignments
including the derivation of glycine from serine—this being derived from the glycolysis intermediate glycerate, which reverses
the order proposed by the self-referential model. Our search identified the glycine-serine pathway of syntheses based on one-carbon
sources, involving activities of the glycine decarboxylase complex and its associated serine hydroxymethyltransferase, which
is consistent with the order proposed by the self-referential model and supports its rationale for the origin of the genetic
code: protein synthesis was developed inside an early metabolic system, serving the function of a sink of amino acids; the
first peptides were glycine-rich and fit for the function of building the early ribonucleoproteins; glycine consumption in
proteins drove the fixation of the glycine-serine pathway. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|