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Three replication origins in Sulfolobus species: synchronous initiation of chromosome replication and asynchronous termination
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Molecular Evolution.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Molecular Evolution.
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2004 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 101, no 18, 7046-7051 p.Article in journal (Refereed) Published
Abstract [en]

Chromosome replication origins were mapped in vivo in the two hyperthermophilic archaea, Sulfolobus acidocaldarius and Sulfolobus solfataricus, by using microarray-based marker frequency analysis. Bidirectional replication was found to be initiated in near synchrony from three separate sites in both organisms. Two of the three replication origins in each species were located in the vicinity of a cdc6/orc1 replication initiation gene, whereas no known replication-associated gene could be identified near the third origin in either organism. In contrast to initiation, replication termination occurred asynchronously, such that certain replication forks continued to progress for >40 min after the others had terminated. In each species, all replication forks advanced at similar DNA polymerization rates; this was found to be an order of magnitude below that displayed by Escherichia coli and thus closer to eukaryotic elongation rates. In S. acidocaldarius, a region containing short regularly spaced repeats was found to hybridize aberrantly, as compared to the rest of the chromosome, raising the possibility of a centromere-like function.

Place, publisher, year, edition, pages
2004. Vol. 101, no 18, 7046-7051 p.
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-95836DOI: 10.1073/pnas.0400656101OAI: oai:DiVA.org:uu-95836DiVA: diva2:170190
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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Lundgren, MagnusBernander, Rolf
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