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Open Access Research

Early evolution of efficient enzymes and genome organization

András Szilágyi12, Ádám Kun123 and Eörs Szathmáry123*

Author Affiliations

1 Department of Plant Taxonomy and Ecology, Institute of Biology, Eötvös University, Pázmány Péter sétány 1/C, 1117, Budapest, Hungary

2 Department of Plant Taxonomy and Ecology, Research Group of Ecology and Theoretical Biology, Eötvös University and The Hungarian Academy of Sciences, Pázmány P. sétány 1/C, H-1117, Budapest, Hungary

3 Parmenides Center for the Conceptual Foundations of Science, Kirchplatz 1, D-82049, Munich/Pullach, Germany

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Biology Direct 2012, 7:38  doi:10.1186/1745-6150-7-38

Published: 31 October 2012

Abstract

Background

Cellular life with complex metabolism probably evolved during the reign of RNA, when it served as both information carrier and enzyme. Jensen proposed that enzymes of primordial cells possessed broad specificities: they were generalist. When and under what conditions could primordial metabolism run by generalist enzymes evolve to contemporary-type metabolism run by specific enzymes?

Results

Here we show by numerical simulation of an enzyme-catalyzed reaction chain that specialist enzymes spread after the invention of the chromosome because protocells harbouring unlinked genes maintain largely non-specific enzymes to reduce their assortment load. When genes are linked on chromosomes, high enzyme specificity evolves because it increases biomass production, also by reducing taxation by side reactions.

Conclusion

The constitution of the genetic system has a profound influence on the limits of metabolic efficiency. The major evolutionary transition to chromosomes is thus proven to be a prerequisite for a complex metabolism. Furthermore, the appearance of specific enzymes opens the door for the evolution of their regulation.

Reviewers

This article was reviewed by Sándor Pongor, Gáspár Jékely, and Rob Knight.

Keywords:
Origin of life; Chromosome; Metabolism; Ribozyme; Major transitions; Enzyme evolution