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Etude de la réplication de l'ADN chez les Archaea

Abstract : Cellular organisms belong to one of the three domains of life: Archaea, Bacteria, and Eucarya. Archaea are unicellular organisms with a bacterial phenotype, yet they exhibit many eucaryotic features at the molecular level. In particular, archaeal DNA replication machinery is a homologous and simplified version of that in eucaryotes. In this work, I have studied archaeal DNA replication with both in vitro and in silico approaches.
First, I have tried to purify the archaeal replication initiator protein Cdc6/Orc1 in its native form, in the hope to set up the first in vitro archaeal DNA replication system. Unfortunately, this approach was not successful, because of the aggregation properties and instability of the protein.
Secondly, I have carried out a comparative analysis of the genome context of DNA replication genes in archaeal genomes. This analysis has led to the identification of a widely conserved association between DNA replication and ribosome-related genes. This genomic organization suggests the existence of a mechanism coupling DNA replication and translation. Remarkably, experimental evidence supporting this idea is emerging piecemeal from biochemical studies in bacteria and eucaryotes. I have then set up some experimental tools that will allow testing some of these in silico predictions in the near future.
Finally, I have examined the taxonomic distribution of DNA replication genes in archaeal genomes in order to infer the probable composition of the DNA replication machinery of the last archaeal common ancestor. Overall, the phyletic patterns of archaeal DNA replication genes suggest that the DNA replication apparatus of this ancestor was likely more complex than that of contemporary archaeal cells.
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Contributor : Jonathan Berthon <>
Submitted on : Wednesday, December 3, 2008 - 5:29:32 PM
Last modification on : Wednesday, September 16, 2020 - 4:53:42 PM
Long-term archiving on: : Monday, June 7, 2010 - 8:47:39 PM


  • HAL Id : tel-00344124, version 1



Jonathan Berthon. Etude de la réplication de l'ADN chez les Archaea. Biochimie [q-bio.BM]. Université Paris Sud - Paris XI, 2008. Français. ⟨tel-00344124⟩



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