Odom W R, Hodges R, Chitnis P R, Guikema J A
Division of Biology, Kansas State University, Manhattan 66506-4901.
Plant Mol Biol. 1993 Dec;23(6):1255-64. doi: 10.1007/BF00042358.
The photosynthetic apparatus is rich in iron-containing cofactors and iron deficiency causes severe impairment of photosynthesis in plants, algae, and cyanobacteria. Synechocystis sp. PCC 6803 serves as a model system to investigate the complex assembly and integration of the multi-subunit protein complexes of oxygenic photosynthetic electron transport; particularly when coupled to developmental cues due to nutrient limitation or requirements. We study Fe(3+)-deficient and Fe(3+)-supplemented cultures of Synechocystis sp. PCC 6803. The autotrophic growth rate of Fe(3+)-deficient cultures is slower than Fe(3+)-supplemented cultures. Whole cell spectral analysis reveals differences in both the quantity and the peak absorbance of chlorophyll. Fe3+ deficiency decreases rates of photosynthetic electron transport and the mRNA and corresponding protein levels as observed using specific probes. mRNA levels of psaB increased 20-fold during recovery from Fe3+ deficiency, as compared to the control. psaD transcript levels increased to 160% during recovery as compared to the control. PsaA/B heterodimer formation and turnover is dependent on Fe3+ and the complete assembly on the reducing side of photosystem I (PS I) is PsaD-dependent. Recovery from Fe3+ deficiency suggests that regulation occurs at both the mRNA and protein level.
光合机构富含含铁辅因子，缺铁会导致植物、藻类和蓝细菌的光合作用严重受损。集胞藻PCC 6803用作研究光合放氧电子传递多亚基蛋白复合物复杂组装和整合的模型系统；特别是当与由于营养限制或需求引起的发育线索相关联时。我们研究了集胞藻PCC 6803的缺铁和铁补充培养物。缺铁培养物的自养生长速率比铁补充培养物慢。全细胞光谱分析揭示了叶绿素在数量和峰值吸光度上的差异。如使用特异性探针所观察到的，缺铁会降低光合电子传递速率以及mRNA和相应蛋白质水平。与对照相比，从缺铁状态恢复期间，psaB的mRNA水平增加了20倍。与对照相比，恢复期间psaD转录本水平增加到160%。PsaA/B异二聚体的形成和周转依赖于铁，并且光系统I（PS I）还原侧的完整组装依赖于PsaD。从缺铁状态恢复表明调节发生在mRNA和蛋白质水平。
