Photochemistry and Photobiology of the Spore Photoproduct: A 50‐Year Journey

Fifty years ago, a new thymine dimer was discovered as the dominant DNA photolesion in UV‐irradiated bacterial spores [Donnellan, J. E. & Setlow R. B. (1965) Science, 149, 308–310], which was later named the spore photoproduct (SP). Formation of SP is due to the unique environment in the spore core that features low hydration levels favoring an A‐DNA conformation, high levels of calcium dipicolinate that acts as a photosensitizer, and DNA saturation with small, acid‐soluble proteins that alters DNA structure and reduces side reactions. In vitro studies reveal that any of these factors alone can promote SP formation; however, SP formation is usually accompanied by the production of other DNA photolesions. Therefore, the nearly exclusive SP formation in spores is due to the combined effects of these three factors. Spore photoproduct photoreaction is proved to occur via a unique H‐atom transfer mechanism between the two involved thymine residues. Successful incorporation of SP into an oligonucleotide has been achieved via organic synthesis, which enables structural studies that reveal minor conformational changes in the SP‐containing DNA. Here, we review the progress on SP photochemistry and photobiology in the past 50 years, which indicates a very rich SP photobiology that may exist beyond endospores.     

生物光化学

生物光化学研究光在动植物体内所引起的生化现象。例如:经过各种不同波长的光辐照后的生命现象,生长规律,某些生理和病理过程,疾病的产生和治疗机理,细胞的辐射损伤和自然防御,以及光合色素在生物进化中的作用等。本文就光引起的现象:视觉、生物钟(光周期性)、植物的光合作用、辐射损伤及其修复、牛皮癣的治疗、新生儿黄疸病的治疗机理,以及光合色素——藻胆蛋白等七种现象,做了综述性的介绍。