Repair of UV-irradiated plasmid DNA in Saccharomyces cerevisiae Inability to complement mutational defects in excision repair by in vitro treatment with Micrococcus luteus UV endonuclease

White, Charles I.; Sedgwick, Steven G.

doi:10.1016/0167-8817(87)90058-7

Cited by 4 publications

(1 citation statement)

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“…Only a limited number of reports have appeared on the repair of yeast plasmids (12)(13)(14)(15)(16)(17)(18). Most of these studies involved repair of exogenously added plasmids, which were damaged as isolated DNA prior to transformation or incubation with cell extracts (13)(14)(15)(16)(17). It was shown that rad 1, 2, 3 and 4 mutants, which all belong to the same epistasis group and are incapable of repairing UV-induced PD in genomic DNA (19), are fully capable of 'reactivating' the exogenously added UV irradiated plasmid DNA (13,14).…”

Section: Introductionmentioning

confidence: 99%

DNA repair in a small yeast plasmid folded into chromatin

Smerdon¹,

Bedoyan²,

Thoma³

1990

Nucl Acids Res

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The question of whether excision repair of yeast plasmids accurately reflects the repair of yeast genomic chromatin has yielded conflicting answers. These conflicts could have arisen from differences in the conformation of plasmid molecules used during these studies. We have examined excision repair of UV photoproducts in a small (2619 bp) autonomously replicating plasmid (YRp-TRURAP), known to be folded into chromatin with positioned nucleosomes in vivo, in the yeast Saccharomyces cerevisiae. A quantitative assay was used to measure the yield of cyclobutane pyrimidine dimers (PD) in plasmid DNA by measuring the fraction of Form I molecules resistant to T4 endonuclease V. After a UV dose of 100 J/m2, which yields 1.2 PD/plasmid in irradiated cells, radiation insensitive (wt) cells repair approximately 70% of the PD in TRURAP chromatin in 2 hr (a rate comparable to that of genomic chromatin). On the other hand, no measurable repair occurs in TRURAP chromatin in radiation sensitive cells (rad1) during the same time period. Thus, this small plasmid contains sufficient chromatin structure in vivo to reflect the incompetent repair of genomic chromatin seen in a rad mutant, while maintaining the competent repair level in wt cells.

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