Oh Min-Hyuk, Safarova Rana B, Eu Young-Jae, Zulfugarov Ismayil S, Kim Jin-Hong, Hwang Hong Jin, Lee Chin Bum, Lee Choon-Hwan
Department of Molecular Biology, Pusan National University, Busan 609-735, Korea.
Photochem Photobiol Sci. 2009 Apr;8(4):535-41. doi: 10.1039/b817808a. Epub 2009 Feb 16.
Photosystem I (PSI) is severely damaged by chilling at 4 degrees C in low light, especially in the chilling sensitive plant cucumber. To investigate the early events in PSI photoinhibition, we examined structural changes in the level of pigment-protein complexes in cucumber leaves in comparison with pea leaves. The complexes were separated on a native green gel and an increase in the intensity of a band was observed only in light-chilled cucumber leaves. The 77 K fluorescence emission spectrum of this green band indicated that the band was mainly composed of PSI with light-harvesting complex I. Each lane was cut from the green gel and separated on a fully denaturing SDS-PAGE in the second dimension. The new green gel band observed after light-chilling in cucumber leaves lacked 19, 18, and 16.5 kDa polypeptides. These results suggest that light-chilling facilitates the release of three peripheral polypeptides as an early event of chilling stress in vivo, which results in the inactivation of PSI in intact cucumber leaves.
光系统I（PSI）在4摄氏度低温弱光条件下会受到严重损伤，在冷敏感植物黄瓜中尤为如此。为了研究PSI光抑制的早期事件，我们将黄瓜叶片与豌豆叶片进行比较，检测了色素-蛋白复合体水平的结构变化。这些复合体在天然绿色凝胶上分离，仅在轻度冷害的黄瓜叶片中观察到一条带的强度增加。这条绿色带的77K荧光发射光谱表明，该带主要由含有光捕获复合体I的PSI组成。从绿色凝胶上切下每条泳道，并在第二维的完全变性SDS-PAGE上进行分离。在黄瓜叶片轻度冷害后观察到的新绿色凝胶带缺乏19、18和16.5 kDa的多肽。这些结果表明，轻度冷害促进了三种外周多肽的释放，这是体内冷胁迫的早期事件，导致完整黄瓜叶片中的PSI失活。
