Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, USA.
Plant Signal Behav. 2010 Jul;5(7):851-3. doi: 10.4161/psb.5.7.11827. Epub 2010 Jul 1.
Photosynthetic organisms display adaptations to changes in light and nutrient availability. Iron, which is required for the function of photosynthetic photosystems and other important biochemical processes, is an essential mineral that consequently impacts not only overall photosynthetic efficiency, but also the physiology of organisms in general. Our recent study represents the first functional characterization of a cyanobacterial TonB protein. TonB proteins classically are membrane proteins that support the transport of iron and vitamin B12 into cells. TonB proteins thus generally serve a critical role in organismal iron acclimation. We recently identified FdTonB, a TonB-family protein, in the filamentous freshwater cyanobacterium Fremyella diplosiphon. FdTonB contains conserved TonB residues and domains, as well as novel protein domains. Our recent study, however, supports a novel function for this protein in the photoregulation of morphology, rather than iron acclimation, in F. diplosiphon. Our detailed investigations into the responses of SF33 wild-type and ΔtonB mutant strains did not support a role for FdTonB in organismal responses to iron limitation. However, close examination of our recent results did highlight a novel interaction between light and iron acclimation in F. diplosiphon.
光合生物表现出对光和养分可利用性变化的适应。铁是光合作用光系统和其他重要生化过程所必需的矿物质，它不仅影响整体光合作用效率，而且影响生物体的生理学。我们最近的研究代表了对蓝细菌 TonB 蛋白的首次功能表征。TonB 蛋白通常是经典的膜蛋白，支持铁和维生素 B12 进入细胞的运输。因此，TonB 蛋白通常在生物体的铁适应中起着关键作用。我们最近在丝状淡水蓝细菌 Fremyella diplosiphon 中鉴定出了 FdTonB，这是一种 TonB 家族蛋白。FdTonB 含有保守的 TonB 残基和结构域，以及新型蛋白结构域。然而，我们最近的研究支持该蛋白在 Fremyella diplosiphon 中形态的光调控而非铁适应中的新功能。我们对 SF33 野生型和 ΔtonB 突变株的反应的详细研究不支持 FdTonB 在生物体对铁限制的反应中的作用。然而，对我们最近的结果的仔细检查确实突出了 Fremyella diplosiphon 中光和铁适应之间的新相互作用。
