Laboratorio de Microbiología Aplicada y Biotecnología, Instituto de Investigaciones en Biodiversidad y Medio Ambiente, Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional del Comahue, Bariloche, Argentina.
Radiat Res. 2011 Jan;175(1):44-50. doi: 10.1667/rr2245.1. Epub 2010 Oct 26.
Several yeast species are able to synthesize and accumulate UV-radiation-absorbing mycosporine metabolites that are of unclear physiological function. In this work we analyzed the relationship between mycosporine-glutaminol glucoside (MGG) production, cell survival after UVB irradiation, and formation of cyclobutane pyrimidine dimers (CPDs). We also assessed the photostability and singlet oxygen quenching activity of MGG. A set of nine isolates of the basidiomycetous yeast Cryptococcus steppossus cultured in both dark and light conditions was used for the studies. Survival of the UVB-irradiated isolates and MGG concentration had a linear relationship when the concentration was over 2.5 mg g(-1). CPD accumulation and MGG accumulation were inversely related. MGG in aqueous solution was photostable with a photodecomposition quantum yield of 1.16 × 10(-5). MGG quenching of singlet oxygen was also observed, and the rate constant for the process in D(2)O was 5.9 × 10(7) M(-1) s(-1). Our results support the idea that MGG plays an important role as a UVB photoprotective metabolite in yeasts by protecting against direct damage on DNA and probably against indirect damage by singlet oxygen quenching.
几种酵母能够合成和积累紫外线吸收的真菌素代谢物，但这些代谢物的生理功能尚不清楚。在这项工作中，我们分析了真菌素-谷氨酰胺葡萄糖苷（MGG）的产生、UVB 照射后细胞存活以及环丁烷嘧啶二聚体（CPD）形成之间的关系。我们还评估了 MGG 的光稳定性和单线态氧猝灭活性。使用了一组在黑暗和光照条件下培养的担子菌酵母隐球菌 steppossus 的九个分离株进行了研究。当浓度超过 2.5mg g(-1)时，经 UVB 照射的分离株的存活率和 MGG 浓度呈线性关系。CPD 积累与 MGG 积累呈负相关。水溶液中的 MGG 具有光稳定性，光分解量子产率为 1.16×10(-5)。还观察到 MGG 对单线态氧的猝灭，在 D(2)O 中的反应速率常数为 5.9×10(7) M(-1) s(-1)。我们的结果支持这样一种观点，即 MGG 通过防止 DNA 直接损伤和可能通过单线态氧猝灭防止间接损伤，作为一种 UVB 光保护代谢物，在酵母中发挥重要作用。
