Huq Enamul, Al-Sady Bassem, Hudson Matthew, Kim Chanhong, Apel Klaus, Quail Peter H
Section of Molecular Cell and Developmental Biology and Institute of Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
Science. 2004 Sep 24;305(5692):1937-41. doi: 10.1126/science.1099728.
Photosynthetic organisms must achieve a delicate balance between the light energy absorbed by chlorophyll and their capacity to channel that energy into productive photochemical reactions. Release of excess absorbed energy in the cell can cause lethal photooxidative damage. We identified a basic helix-loop-helix (bHLH) transcription factor, designated PHYTOCHROME-INTERACTING FACTOR 1 (PIF1), that negatively regulates chlorophyll biosynthesis. pif1 mutant seedlings accumulate excess free protochlorophyllide when grown in the dark, with consequent lethal bleaching upon exposure to light. PIF1 interacts specifically with the photoactivated conformer of phytochromes A and B, suggesting a signaling pathway by which chlorophyll biosynthetic rates are tightly controlled during the critical initial emergence of seedlings from subterranean darkness into sunlight.
光合生物必须在叶绿素吸收的光能与其将该能量导入有效的光化学反应的能力之间实现微妙的平衡。细胞中过量吸收能量的释放会导致致命的光氧化损伤。我们鉴定出一种碱性螺旋-环-螺旋（bHLH）转录因子，命名为光敏色素相互作用因子1（PIF1），它对叶绿素生物合成起负调控作用。pif1突变体幼苗在黑暗中生长时会积累过量的游离原叶绿素酸酯，因此在光照下会出现致命的白化现象。PIF1与光敏色素A和B的光活化构象特异性相互作用，这表明在幼苗从地下黑暗环境初次暴露于阳光的关键阶段，存在一条严格控制叶绿素生物合成速率的信号通路。
