In this work a range of recombination mutants were screened for their ability to carry out successful recombinational repair of SbcCD-generated double-strand breaks a the site of a long chromosomal palindrome. The results obtained suggest that the components of both the RecB and RecF pathways are required for successful recombinational repair of SbcCD-generated breaks at the site of the palindrome. This breakage and repair process does not seem to involve replication fork breakage. In the absence of SbcCD recombination still occurs, apparently through the RecF gap-recombination pathway. Once again, this process appears to avoid replication fork collapse. In the absence of recombination, the RecQ helicase was found to be essential to the viability of <i>sbcC</i> cells possessing the palindrome. This suggests that RecQ is involved in a pathway allowing replicative bypass of secondary structure, probably through helicase unwinding of the secondary structure. Using an <i>xerC</i> mutant deficient in the resolution of chromosome dimers, the relationship between recombination at the site of the palindrome and crossing-over was investigated. It was observed that double-strand break repair at the site of the palindrome is associated with crossing-over whereas single-strand gap recombination is not. Using UV irradiation of cells deficient for excision repair it was demonstrated that the association of double-strand break repair, but not single-strand gap repair, with crossing over is a genera phenomenon. The observation that in P1 transduction mainly cross-over products are observed supports the idea that these effects are the result of a rule governing the resolution of Holliday junctions. The random resolution of Holliday junctions in <i>ruvABC</i> mutants suggests that this rule operates through the RuvABC Holliday junction resolution complex.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:645169 |
| Date | January 2000 |
| Creators | Cromie, Gareth Andrew |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13494 |
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