DNA replication origins in Haloferax volcanii
DNA replication is fundamental to the proliferation of life. Sites of DNA replication initiation are called replication origins. Bacteria replicate from a single origin whereas eukaryotes utilise multiple origins for each chromosome. The archaeal domain includes species which replicate using multipl...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English |
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2009
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| Online Access: | https://eprints.nottingham.ac.uk/10853/ |
| _version_ | 1848791142329483264 |
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| author | Hawkins, Michelle |
| author_facet | Hawkins, Michelle |
| author_sort | Hawkins, Michelle |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | DNA replication is fundamental to the proliferation of life. Sites of DNA replication initiation are called replication origins. Bacteria replicate from a single origin whereas eukaryotes utilise multiple origins for each chromosome. The archaeal domain includes species which replicate using multiple origins of replication in addition to those which use a single origin. Archaeal DNA replication proteins are similar to eukaryotic replication machinery. Most characterised archaeal origins are adjacent to an orc gene which encodes a homologue of the Orc1 subunit of the eukaryotic initiator protein complex.
Replication origins of the halophilic archaeon Haloferax volcanii were identified using a combination of genetic, biochemical and bioinformatic approaches. H. volcanii has a multireplicon genome consisting of a circular main chromosome and three mini-chromosomes: pHV1, pHV3 and pHV4. The major chromosome contains multiple origins of replication and is the first example of multiple origins on a single replicon in the Euryarchaeota. Each characterised origin is adjacent to an orc gene and contains repeated sequence motifs surrounding an A/T-rich duplex unwinding element.
The archaeal recombinase, RadA, is homologous to eukaryotic and bacterial Rad51/RecA. It is widely held that deletion of radA results in elimination of homologous recombination. In this study the discovery of a radA-independent recombination pathway specific to replication origins is described. This dynamic mechanism was identified by observing chromosomal integration of plasmids containing H. volcanii replication origins in a radA deletion strain.
The eukaryotic RAD25 gene is involved in nucleotide excision repair and transcription. H. volcanii has four RAD25 homologues, one on pHV4 and three near the oriC-2 locus on the main chromosome. A role for the assistance of oriC-2 firing is proposed based on autonomously replicating plasmid assays. Deletion of all four RAD25 homologues did not increase DNA damage sensitivity but resulted in a minor growth defect. |
| first_indexed | 2025-11-14T18:23:48Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-10853 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T18:23:48Z |
| publishDate | 2009 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-108532025-02-28T11:09:59Z https://eprints.nottingham.ac.uk/10853/ DNA replication origins in Haloferax volcanii Hawkins, Michelle DNA replication is fundamental to the proliferation of life. Sites of DNA replication initiation are called replication origins. Bacteria replicate from a single origin whereas eukaryotes utilise multiple origins for each chromosome. The archaeal domain includes species which replicate using multiple origins of replication in addition to those which use a single origin. Archaeal DNA replication proteins are similar to eukaryotic replication machinery. Most characterised archaeal origins are adjacent to an orc gene which encodes a homologue of the Orc1 subunit of the eukaryotic initiator protein complex. Replication origins of the halophilic archaeon Haloferax volcanii were identified using a combination of genetic, biochemical and bioinformatic approaches. H. volcanii has a multireplicon genome consisting of a circular main chromosome and three mini-chromosomes: pHV1, pHV3 and pHV4. The major chromosome contains multiple origins of replication and is the first example of multiple origins on a single replicon in the Euryarchaeota. Each characterised origin is adjacent to an orc gene and contains repeated sequence motifs surrounding an A/T-rich duplex unwinding element. The archaeal recombinase, RadA, is homologous to eukaryotic and bacterial Rad51/RecA. It is widely held that deletion of radA results in elimination of homologous recombination. In this study the discovery of a radA-independent recombination pathway specific to replication origins is described. This dynamic mechanism was identified by observing chromosomal integration of plasmids containing H. volcanii replication origins in a radA deletion strain. The eukaryotic RAD25 gene is involved in nucleotide excision repair and transcription. H. volcanii has four RAD25 homologues, one on pHV4 and three near the oriC-2 locus on the main chromosome. A role for the assistance of oriC-2 firing is proposed based on autonomously replicating plasmid assays. Deletion of all four RAD25 homologues did not increase DNA damage sensitivity but resulted in a minor growth defect. 2009-07-22 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en arr https://eprints.nottingham.ac.uk/10853/1/Michelle_Hawkins_PhD_thesis.pdf Hawkins, Michelle (2009) DNA replication origins in Haloferax volcanii. PhD thesis, University of Nottingham. DNA replication Haloferax volcanii Archaebacteria Bacterial genetics |
| spellingShingle | DNA replication Haloferax volcanii Archaebacteria Bacterial genetics Hawkins, Michelle DNA replication origins in Haloferax volcanii |
| title | DNA replication origins in Haloferax volcanii |
| title_full | DNA replication origins in Haloferax volcanii |
| title_fullStr | DNA replication origins in Haloferax volcanii |
| title_full_unstemmed | DNA replication origins in Haloferax volcanii |
| title_short | DNA replication origins in Haloferax volcanii |
| title_sort | dna replication origins in haloferax volcanii |
| topic | DNA replication Haloferax volcanii Archaebacteria Bacterial genetics |
| url | https://eprints.nottingham.ac.uk/10853/ |