Polidoros A N, Scandalios J G
Department of Genetics, North Carolina State University, Raleigh 27695-7614, USA.
Free Radic Biol Med. 1997;23(3):497-504. doi: 10.1016/s0891-5849(97)00110-x.
The three maize catalase genes respond differentially to light signals. Expression of Cat1 is light independent while expression of Cat2 and Cat3 is light responsive. Upon exposure to light there is rapid accumulation of CAT-2 protein in leaves, due to both increased transcript accumulation and increased translation of the Cat2 message. Short UV light pulses also cause a strong transient induction of Cat2 gene expression, while long term exposure to UV does not affect the rate of Cat2 transcription. The Cat3 gene of maize exhibits a transcriptionally regulated circadian rhythm. The induction of the Cat3 circadian expression in etiolated leaves is probably regulated by a very low fluence phytochrome response; the involvement of a blue light/UV-A and a UV-B photoreceptor is also possible. Regulatory elements located on the Cat3 promoter have recently been identified and their significance in the complex light response of the gene is being investigated. Possible physiological role(s) of the light responding maize catalases Cat2 and Cat3 are discussed.
三种玉米过氧化氢酶基因对光信号的反应存在差异。Cat1的表达不依赖于光，而Cat2和Cat3的表达对光有反应。暴露于光下时，由于转录本积累增加和Cat2信息的翻译增加，叶片中CAT-2蛋白迅速积累。短时间的紫外光脉冲也会强烈短暂诱导Cat2基因表达，而长期暴露于紫外光下不会影响Cat2的转录速率。玉米的Cat3基因表现出转录调控的昼夜节律。黄化叶片中Cat3昼夜表达的诱导可能受极低光通量的光敏色素反应调控；蓝光/UV-A和UV-B光受体也可能参与其中。最近已鉴定出位于Cat3启动子上的调控元件，并且正在研究它们在该基因复杂光反应中的意义。文中还讨论了对光有反应的玉米过氧化氢酶Cat2和Cat3可能的生理作用。
