Evolution of the Division of Labor between Genes and Enzymes in the RNA World
Boza, Gergely (Eötvös Loránd University. Department of Plant Systematics, Ecology and Theoretical Biology)
Szilágyi, András (Eötvös Loránd University. Department of Plant Systematics, Ecology and Theoretical Biology)
Kun, Ádám (Eötvös Loránd University. Department of Plant Systematics, Ecology and Theoretical Biology)
Santos, Mauro (Universitat Autònoma de Barcelona. Departament de Genètica i de Microbiologia)
Szathmáry, Eörs (Eötvös Loránd University. Department of Plant Systematics, Ecology and Theoretical Biology)

Data:	2014
Resum:	The RNA world is a very likely interim stage of the evolution after the first replicators and before the advent of the genetic code and translated proteins. Ribozymes are known to be able to catalyze many reaction types, including cofactor-aided metabolic transformations. In a metabolically complex RNA world, early division of labor between genes and enzymes could have evolved, where the ribozymes would have been transcribed from the genes more often than the other way round, benefiting the encapsulating cells through this dosage effect. Here we show, by computer simulations of protocells harboring unlinked RNA replicators, that the origin of replicational asymmetry producing more ribozymes from a gene template than gene strands from a ribozyme template is feasible and robust. Enzymatic activities of the two modeled ribozymes are in trade-off with their replication rates, and the relative replication rates compared to those of complementary strands are evolvable traits of the ribozymes. The degree of trade-off is shown to have the strongest effect in favor of the division of labor. Although some asymmetry between gene and enzymatic strands could have evolved even in earlier, surface-bound systems, the shown mechanism in protocells seems inevitable and under strong positive selection. This could have preadapted the genetic system for transcription after the subsequent origin of chromosomes and DNA. The RNA world refers to the stage of early evolution when RNA macromolecules were responsible both for storing hereditary information and performing enzymatic activities. Conflict arises between these two functions, however, as enzymatic activities of the ribozymes are in tradeoff with their replication rates. Here we address this problem by investigating the evolutionary emergence of a primordial transcription-like system in model protocells inhabited by unlinked replicators. Our numerical analysis demonstrates that division of labor between genes and enzymes could have emerged, given that there was a moderate to strong tradeoff between the enzymatic and template efficiency of one strand of the ribozymes. This division of labor results in a strong asymmetry in the numbers of the enzymatic and genetic strands of the macromolecules, in favor of the former. We offer insight into the emergence of the first transcription-like system, which is today characteristic of all known life forms.
Ajuts:	European Commission 294332 Ministerio de Ciencia e Innovación CGL2010-15395 Ministerio de Economía y Competitividad CGL2013-42432
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	PLoS computational biology, Vol. 10, Issue 12 (December 2014) , art. e1003936, ISSN 1553-7358

DOI: 10.1371/journal.pcbi.1003936
PMID: 25474573

9 p, 2.0 MB

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