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The stereochemical basis of the genetic code and the (mostly) autotrophic origin of life

Vendredi 16 janvier 2015 11:00 - Duree : 1 heure
Lieu : IBS, 71 av. des Martyrs, campus EPN, Grenoble

Orateur : Juan FONTECILLA-CAMPS (IBS/Groupe Métalloprotéines)

Spark-tube experiments and analysis of meteorite contents have led to the widespread notion that abiotic organic molecules were the first components of life. However, there is a contradiction between the preponderance of relatively simple molecules, such as the amino acids glycine and alanine, and the minimal functional complexity that even the least sophisticated living system should require. I will argue that although simple abiotic molecules must have primed proto-metabolic pathways, only evolving systems, in the Darwinian sense, could have generated life. This condition may have been initially fulfilled by both RNAs and autocatalytic reaction chains, such as the reductive citric acid cycle. Besides conferring new functionalities, the acylation of nucleic acids by biotic amino acids may have resulted in their progressive stereochemical recognition by cognate anticodons. At this point only large enough amino acids would be recognized by the primordial RNA adaptors and could polymerize forming the first peptides. A crucial event took place when RNA adaptors underwent gene duplication. By placing one of the anticodon regions away from the acceptor stem the new RNA adaptor liberated itself from the stereochemical constrain and could be acylated by smaller amino acids. The emergence of messenger RNA and codon capture followed.

Contact : ibs.seminaires@ibs.fr

Discipline évènement : (Biologie / Chimie)
Entité organisatrice : (IBS)
Nature évènement : (Séminaire)
Evènement répétitif : (Séminaire IBS)
Site de l'évènement : Polygone scientifique

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