Use this URL to cite or link to this record in EThOS:
Title: The excision repair of base damage in Saccharomyces cerevisiae
Author: Scott, A. D.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1997
Availability of Full Text:
Access from EThOS:
In Saccharomyces cerevisiae RAD7 and RAD16 are required for nucleotide excision repair (NER) of CPDs in nontranscribed regions of the genome. An inducible component to NER in yeast is examined in this thesis. Excision of CPDs and a minor UV induced lesion characterised by sensitivity to endonuclease III (EIIISS), is enhanced following a prior UV irradiation. No enhancement of repair is detected in either the rad7Δ or the rad16Δ mutant. Since repair of EIIISS in transcriptionally silent DNA is independent of RAD7 and RAD16, these two genes may have two roles in NER: repair of CPDs from nontranscribed sequences; and enhancing NER of lesions generally. Events were also examined at stages of the mitotic cycle. Repair of CPDs is not significantly different in any stage following a single UV dose. However, induction of enhanced excision of CPDs is confined to G1 and Early S. To assess the role of NER in the repair of oxidative DNA damage, mutants were constructed by deletion of the RAD14 gene in wild type cells and in mutants defective in OGG1 (8-oxoguanine-DNA-glycosylase). ogg1 mutants exhibit a spontaneous GC-TA mutator phenotype. Mutation to canavanine resistance is elevated 5-fold in rad14 mutants, and is additively increased in ogg1 rad14 double mutants. However, reversion of the lys1-1 mutation is not increased with deletion of RAD14. These data suggest that the NER machinery competes with Ogg1 for oxidative base damage in certain areas of the genome. A GC-TA mutation in a tRNASer gene allows suppression of the lys1-1 ochre allele. Interestingly, CPDs are inefficiently repaired in this gene, compared to previous reports for genes transcribed by RNA polymerase II. A model is presented linking the efficiency of NER in specific genes with the nature of the transcribing polymerase.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available