Reduction-dependent siderophore assimilation in a model pennate diatom
Reduction-dependent siderophore assimilation in a model pennate diatom
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DOI：
10.1073/pnas.1907234116
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发表时间：
2019-11-19
影响因子：
11.1
通讯作者：
Allen, Andrew E.
中科院分区：
文献类型：
--
作者：
Coale, Tyler H.;Moosburner, Mark;Allen, Andrew E.
硅藻对铁的吸收是一个具有全球生态地球化学意义的生物化学过程。在海洋表面的大部分区域，硅藻负责主要的初级生产，并经常经历铁的生长限制。这些浮游植物从海水中提取铁的策略限制了碳通量进入更高的营养级和封存到沉积物中。在这项研究中，我们使用反向遗传技术的目标模式羽状硅藻三角褐指藻铁的收购基因。我们描述了依赖于细菌衍生的受体蛋白的还原依赖性铁载体获取途径的组成部分，并在某些条件下提供了无机铁摄取的可行替代方案。这种形式的铁吸收需要在低铁条件下硅藻和产生铁载体的生物体之间的密切联系。这些蛋白质的同源物被发现分布在整个硅藻谱系，这表明在海洋环境中的硅藻铁载体利用的意义。特定蛋白质的评估使我们能够确认硅藻中独立的铁获取途径，并表征其首选底物。这些发现完善了我们对硅藻使用的多个铁吸收系统的机械理解，并帮助我们更好地预测铁形态对分类群特异性铁生物利用度的影响。
Iron uptake by diatoms is a biochemical process with global biogeochemical implications. In large regions of the surface ocean diatoms are both responsible for the majority of primary production and frequently experiencing iron limitation of growth. The strategies used by these phytoplankton to extract iron from seawater constrain carbon flux into higher trophic levels and sequestration into sediments. In this study we use reverse genetic techniques to target putative iron-acquisition genes in the model pennate diatom Phaeodactylum tricornutum. We describe components of a reduction-dependent siderophore acquisition pathway that relies on a bacterial-derived receptor protein and provides a viable alternative to inorganic iron uptake under certain conditions. This form of iron uptake entails a close association between diatoms and siderophore-producing organisms during low-iron conditions. Homologs of these proteins are found distributed across diatom lineages, suggesting the significance of siderophore utilization by diatoms in the marine environment. Evaluation of specific proteins enables us to confirm independent iron-acquisition pathways in diatoms and characterize their preferred substrates. These findings refine our mechanistic understanding of the multiple iron-uptake systems used by diatoms and help us better predict the influence of iron speciation on taxa-specific iron bioavailability.