A Comparative Study of Iron Uptake Mechanisms in Marine Microalgae: Iron Binding at the Cell Surface Is a Critical Step1[W][OA]
A Comparative Study of Iron Uptake Mechanisms in Marine Microalgae: Iron Binding at the Cell Surface Is a Critical Step1[W][OA]
复制标题
海洋微藻铁吸收机制的比较研究：铁在细胞表面的结合是关键步骤1[W][OA]
作者：
R. Sutak;Hugo Botebol;P. Blaiseau;T. Léger;F. Bouget;J. Camadro;E. Lesuisse
我们研究了五种海洋微藻的铁吸收机制，这些微藻来自不同的生态重要的门：硅藻三角褐指藻和海链藻，绿藻纲的Ostreococcus tauri和Microconas pusilla，以及球石藻Emiliania huxleyi。在这些物种中，只有两种硅藻明显能够通过诱导型（三角褐指藻）或组成型（三角褐指藻）还原铁。该系统显示出与酵母（酿酒酵母）黄素血红素蛋白相似的特征。铁吸收机制可能涉及非常不同的组件根据物种，但我们研究的物种共享的共同特征。无论铁还原酶系统的存在和/或诱导，所有物种都能够吸收三价铁和二价铁，并且铁还原不是吸收的先决条件。铁的摄取量随着铁-配体络合物的亲和常数的增加和配体-铁比率的增加而降低。因此，铁吸收机制的至少一个步骤涉及一个化学控制的过程。另一个步骤逃避简单的热力学规则，涉及在铁吸收之前在细胞表面特异性和强结合三价铁和二价铁。自相矛盾的是，在富含铁的条件下，结合增加，而吸收本身诱导所有物种只有在长时间的铁剥夺。我们寻找在铁摄取后负载铁的细胞蛋白。O. tauri可能是铁蛋白，而在三角褐指藻中，可能涉及Isip 1。我们的结论是，我们研究的物种都吸收系统的三价铁和二价铁，都涉及特定的铁结合在细胞表面。
We investigated iron uptake mechanisms in five marine microalgae from different ecologically important phyla: the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana, the prasinophyceae Ostreococcus tauri and Micromonas pusilla, and the coccolithophore Emiliania huxleyi. Among these species, only the two diatoms were clearly able to reduce iron, via an inducible (P. tricornutum) or constitutive (T. pseudonana) ferrireductase system displaying characteristics similar to the yeast (Saccharomyces cerevisiae) flavohemoproteins proteins. Iron uptake mechanisms probably involve very different components according to the species, but the species we studied shared common features. Regardless of the presence and/or induction of a ferrireductase system, all the species were able to take up both ferric and ferrous iron, and iron reduction was not a prerequisite for uptake. Iron uptake decreased with increasing the affinity constants of iron-ligand complexes and with increasing ligand-iron ratios. Therefore, at least one step of the iron uptake mechanism involves a thermodynamically controlled process. Another step escapes to simple thermodynamic rules and involves specific and strong binding of ferric as well as ferrous iron at the cell surface before uptake of iron. Binding was paradoxically increased in iron-rich conditions, whereas uptake per se was induced in all species only after prolonged iron deprivation. We sought cell proteins loaded with iron following iron uptake. One such protein in O. tauri may be ferritin, and in P. tricornutum, Isip1 may be involved. We conclude that the species we studied have uptake systems for both ferric and ferrous iron, both involving specific iron binding at the cell surface.
影响因子：
2.9
作者：
Kwok, Ernest Y.;Severance, Scott;Kosman, Daniel J.
通讯作者：
Kosman, Daniel J.