Schmidt C L, Grey M, Schmidt M, Brendel M, Henriques J A
Departamento de Biofisica/Centro de Biotecnologia, UFRGS, A. Bento Goncalves 9500, 91507-970 Porto Alegre, RS, Brazil.
Yeast. 1999 Oct;15(14):1503-10. doi: 10.1002/(sici)1097-0061(199910)15:14<1503::aid-yea481>3.3.co;2-n.
Sequencing of the yeast gene that complemented the sensitivity to the photoactivated monofunctional 3-carbethoxypsoralen of the pso6-1 mutant strain revealed that the ERG3 locus, encoding sterol C-5 desaturase involved in biosynthesis of ergosterol, is allelic to PSO6. Disruption of the ERG3 gene yielded an erg3Delta mutant viable in ergosterol-containing YEPD media with the same pleiotropic mutant phenotype known for pso6-1 and erg3 mutants, including sensitivity to hydrogen peroxide and paraquat. Thus, the erg3/pso6 yeast mutant seems to be more sensitive than the WT to 3-CPs+UVA because of the oxidative damage contributed by this treatment and not because of an impaired repair of the furocoumarin-thymine monoadducts formed in the DNA. We found a significant increase of petites amongst erg3Delta and pso6-1 yeast mutant strains grown in conditions where respiration was mandatory. Mutant pso6-1, with its lowered content of ergosterol, exhibited enhanced synthesis of chitin that was maldistributed and not confined to the bud scars. Chitin overproduction in pso6/erg3 mutants resulted in hypersensitivity to Calcofluor White.
对能够互补pso6 - 1突变菌株对光活化单功能3 - 乙氧羰基补骨脂素敏感性的酵母基因进行测序后发现，编码参与麦角固醇生物合成的固醇C - 5去饱和酶的ERG3基因座与PSO6等位。ERG3基因的破坏产生了一个erg3Δ突变体，该突变体在含有麦角固醇的YEPD培养基中可存活，具有与pso6 - 1和erg3突变体相同的多效突变表型，包括对过氧化氢和百草枯敏感。因此，erg3/pso6酵母突变体对3 - CPs + UVA似乎比野生型更敏感，这是由于这种处理导致的氧化损伤，而不是因为DNA中形成的呋喃香豆素 - 胸腺嘧啶单加合物的修复受损。我们发现在呼吸是必需条件下生长的erg3Δ和pso6 - 1酵母突变体菌株中，小菌落显著增加。具有降低的麦角固醇含量的突变体pso6 - 1表现出几丁质合成增强，几丁质分布不均且不限于芽痕。pso6/erg3突变体中几丁质的过量产生导致对荧光增白剂高度敏感。
