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Identification of two origins of replication in the single chromosome of the archaeon Sulfolobus solfataricus
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Molecular Evolution.
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2004 (English)In: Cell, ISSN 0092-8674, E-ISSN 1097-4172, Vol. 116, no 1, 25-38 p.Article in journal (Refereed) Published
Abstract [en]

Eukaryotic chromosomes possess multiple origins of replication, whereas bacterial chromosomes are replicated from a single origin. The archaeon Pyrococcus abyssi also appears to have a single origin, suggesting a common rule for prokaryotes. However, in the current work, we describe the identification of two active origins of replication in the single chromosome of the hyperthermophilic archaeon Sulfolobus solfataricus. Further, we identify conserved sequence motifs within the origins that are recognized by a family of three Sulfolobus proteins that are homologous to the eukaryotic initiator proteins Orc1 and Cdc6. We demonstrate that the two origins are recognized by distinct subsets of these Orc1/Cdc6 homologs. These data, in conjunction with an analysis of the levels of the three Orc1/Cdc6 proteins in different growth phases and cell cycle stages, lead us to propose a model for the roles for these proteins in modulating origin activity.

Place, publisher, year, edition, pages
2004. Vol. 116, no 1, 25-38 p.
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-95835DOI: 10.1016/S0092-8674(03)01034-1OAI: oai:DiVA.org:uu-95835DiVA: diva2:170189
Available from: 2007-04-26 Created: 2007-04-26 Last updated: 2011-02-18Bibliographically approved
In thesis
1. Exploring the Cell Cycle of Archaea
Open this publication in new window or tab >>Exploring the Cell Cycle of Archaea
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Archaea is the third domain of life, discovered only thirty years ago. In a microscope archaea appear indistinguishable from bacteria, but they have been shown to be more closely related to eukaryotes than to bacteria. Especially central information processing is homologous to that of eukaryotes. The archaea, previously thought to be limited to extreme environments, constitute a large part of life on Earth to an extent that has only begun to be understood. Despite their abundance little is known about several central cell-cycle features, such as cell division and genome segregation.

For this thesis, a comprehensive study of the cell cycle in the model archaeon Sulfolobus acidocaldarius was performed, describing the majority of its cell-cycle regulated genes. Several known DNA replication genes, as well as genes previously not known to have a role in the cell cycle, displayed cyclic transcription. Several transcription factors, kinases and DNA sequence elements were identified as cell-cycle regulatory elements. Among the most important findings were putative cell division and genome segregation machineries.

Sulfolobus species were discovered to have three origins of replication, constituting the first known prokaryotes with multiple origins. All origins initiate replication in a synchronous manner. Cdc6 proteins were shown to bind to origin recognition boxes conserved across the Archaea domain. Two Cdc6 proteins function as replication initiators, while a third paralog is implicated as a negative factor. Replication was shown to proceed at a rate similar to that of eukaryotes.

A particular type of cell cycle organization was found to be unusually conserved in the Crenachaeota phylum. All the studied species displayed a short prereplicative phase and a long postreplicative phase, and cycle between one and two genome copies. Genome sizes were determined for several species. The euryarchaeon Methanothermobacter thermautotrophicus was also studied, and it was shown to initiate genome segregation during, or just after, replication. In contrast to the crenarchaea it never displayed a single genome copy per cell.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 71 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 300
Microbiology, Archaea, Cell cycle, Replication, Mitosis, Cell division, Mikrobiologi
urn:nbn:se:uu:diva-7848 (URN)978-91-554-6881-1 (ISBN)
Public defence
2007-05-18, Lindahlsalen, Evolutionsbiologiskt centrum, Norbyvägen 18, Uppsala, 13:15
Available from: 2007-04-26 Created: 2007-04-26Bibliographically approved

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