Li X P, Björkman O, Shih C, Grossman A R, Rosenquist M, Jansson S, Niyogi K K
Department of Plant and Microbial Biology, University of California, Berkeley 94720-3102, USA.
Nature. 2000 Jan 27;403(6768):391-5. doi: 10.1038/35000131.
Photosynthetic light harvesting in plants is regulated in response to changes in incident light intensity. Absorption of light that exceeds a plant's capacity for fixation of CO2 results in thermal dissipation of excitation energy in the pigment antenna of photosystem II by a poorly understood mechanism. This regulatory process, termed nonphotochemical quenching, maintains the balance between dissipation and utilization of light energy to minimize generation of oxidizing molecules, thereby protecting the plant against photo-oxidative damage. To identify specific proteins that are involved in nonphotochemical quenching, we have isolated mutants of Arabidopsis thaliana that cannot dissipate excess absorbed light energy. Here we show that the gene encoding PsbS, an intrinsic chlorophyll-binding protein of photosystem II, is necessary for nonphotochemical quenching but not for efficient light harvesting and photosynthesis. These results indicate that PsbS may be the site for nonphotochemical quenching, a finding that has implications for the functional evolution of pigment-binding proteins.
植物中的光合光捕获是根据入射光强度的变化进行调节的。吸收超过植物固定二氧化碳能力的光会通过一种尚未完全了解的机制，导致光系统II色素天线中激发能的热耗散。这个调节过程称为非光化学猝灭，它维持了光能耗散与利用之间的平衡，以尽量减少氧化分子的产生，从而保护植物免受光氧化损伤。为了鉴定参与非光化学猝灭的特定蛋白质，我们分离了拟南芥中不能耗散过量吸收光能的突变体。我们在此表明，编码光系统II内在叶绿素结合蛋白PsbS的基因对于非光化学猝灭是必需的，但对于高效的光捕获和光合作用则不是必需的。这些结果表明，PsbS可能是非光化学猝灭的位点，这一发现对色素结合蛋白的功能进化具有重要意义。
