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A self-referential model for the formation of the genetic code.
Guimarães, Romeu Cardoso; Moreira, Carlos Henrique Costa; de Farias, Sávio Torres.
Affiliation
  • Guimarães RC; Dept. Biologia Geral, Inst. Ciências Biológicas, Univ. Federal de Minas Gerais, Belo Horizonte, MG , 31270.901, Brazil. romeucg@icb.ufmg.br
Theory Biosci ; 127(3): 249-70, 2008 Aug.
Article in En | MEDLINE | ID: mdl-18493811
A model for the formation of the genetic code is presented where protein synthesis is directed initially by tRNA dimers. Proteins that are resistant to degradation and efficient RNA-binders protect the RNAs. Replication becomes elongational producing poly-tRNAs from which the mRNAs and ribosomes are derived. Attributions are successively fixed to tRNAs paired through the perfect palindromic anticodons, with the same bases at the extremities (5'ANA: UNU 3'; GNG: CNC; principal dinucleotides, pDiN). The 5' degeneracy is then developed. The first pairs to be encoded correspond to the hydropathy correlation outliers (Gly-CC: Pro-GG and Ser-GA: Ser-CU) and to the sector of homogeneous pDiN, composed by two pyrimidines or two purines. These amino acids are preferred in the N-ends of proteins, stabilizers of proteins against catabolism and strong RNA-binders. The next pairs complete the sector of homogeneous pDiN (Asp, Glu-UC: Leu-AG and Asn, Lys-UU: Phe-AA). This set of nine amino acids forms the protein cores with the predominant aperiodic conformation. Next enter the pairs with mixed pDiN (one purine and one pyrimidine), the RY attributions composing the protein N-ends and the YR attributions the C-ends. The last pair contains the main punctuation signs (Ile, Met, iMet-AU: Tyr, Stop-UA). The model indicates that genetic information emerged during the process of formation of the coding/decoding system and that genes were defined by the proteins. Stable proteins constructed the nucleoprotein system by binding to the RNAs that produced them. In this circular rationale, genes are memories in a metabolic system for production of proteins that stabilize it. The simplicity and the highly deterministic character of the process suggest that the Last Universal Common Ancestor populations could be composed, in early stages, of lineages bearing similar genetic codes.
Subject(s)

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Genetic Code / Amino Acids Language: En Journal: Theory Biosci Journal subject: BIOLOGIA Year: 2008 Document type: Article Affiliation country: Brazil Country of publication: Germany

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Genetic Code / Amino Acids Language: En Journal: Theory Biosci Journal subject: BIOLOGIA Year: 2008 Document type: Article Affiliation country: Brazil Country of publication: Germany