摘要
隐藻藻胆蛋白在类囊体腔中的存在状态始终存在争议,为了深入了解这一问题,作者以含有藻蓝蛋白(PC645)的蓝隐藻(Chroomonas placoidea)活体细胞及充分洗涤过的类囊体膜为材料,测定其室温吸收光谱、荧光谱以及77K低温荧光光谱,并根据光谱数据分析了PC在类囊体腔中的存在状态。结果显示,蓝隐藻的类囊体膜上始终紧密结合着一定量的PC,并且很可能是以PC的β亚基与膜相接触,证实藻胆蛋白在类囊体腔中不是完全游离的,与膜的接触也并非完全无倾向性排布;PC既可将激发能传递给光系统(PS)II,但也可传递给PSI,相较于叶绿素(Chl)a和Chl c,在PSI长波荧光中PC的贡献更明显,而Chl c吸收的光能,更倾向于传递给PSII或者短波长Chl a;蓝隐藻细胞中表现出超比例的PC荧光发射,说明除了结合在膜上的PC外,有一部分PC是游离的,其存在对于隐藻捕光功能来说可能是有冗余的;游离的PC可与类囊体膜重新接触而恢复能量传递功能。根据实验结果以及前人的报道,提出了隐藻藻胆蛋白与类囊体膜的结合是动态的观点,并给出了相应的模型。
The existential states of cryptomonad phycobiliproteins in thylakoidal lumen have always been controversial. In order to elucidate this question further, the absorption spectra as well as fluorescence spectra（at both room temperature and 77 K） of intact cells and thylakoids of Chroomonas placoidea containing phycocyanin（PC） were determined in this paper. The existential states of PC within thylakoid lumen are discussed according to the data from spectral analysis. The results show that a portion of PC tightly combined to the thylakoid membrane at any time（possibly attached with its β subunit）, suggesting that the cryptomonad phycobiliproteins are neither fully isolated across the thylakoid lumen, nor completely have no preference in contacting with thylakoid, and PC functionally transfers excited energy to both photosystem（PS） I and PSII, and contributes more to the long-wavelength of fluorescence from PSI compared to Chlorophyll（Chl） a and Chl c, while Chl c prefers to transfer excited energy to PSII or short-wavelength of Chl a. The observation of ultrahigh ratio of fluorescence emitted by PC in intact cells indicates the existence of free PC, which may be redundant for light-harvesting. These freely existed PC may associate with thylakoid and revive their light-harvesting function in due time. Considering the results above and those from previous studies, we raise such a point of view that the combination between cryptomonad phycobiliproteins and thylakoid are dynamic, and a corresponding model is described here.
出处
《海洋科学》
CAS
CSCD
北大核心
2015年第4期21-29,共9页
Marine Sciences
基金
国家自然科学基金资助项目(40976083)
