Sequence analysis and transcriptional regulation of iron acquisition genes in two marine diatoms
Sequence analysis and transcriptional regulation of iron acquisition genes in two marine diatoms
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DOI：
10.1111/j.1529-8817.2007.00359.x
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发表时间：
2007-08-01
影响因子：
2.9
通讯作者：
Morel, Francois M. M.
中科院分区：
文献类型：
--
作者：
Kustka, Adam B.;Allen, Andrew E.;Morel, Francois M. M.
中心的硅藻Thalassiosira dangerana Hasle et Heimdal和羽状硅藻Phaeodactylum tricornutum Bohlin具有与模式生物中存在的高亲和力铁还原酶同源的翻译序列的基因。海链藻还具有膜结合铁氧化酶（TpFET 3）和两种高度相似的铁（Fe）渗透酶（TpFTR 1和TpFTR 2）的推定基因，以及属于NRAMP超家族的二价金属（M2+）转运蛋白（TpNRAMP）。在面包酵母中，铁氧化酶-透性酶复合物运输还原酶产生的Fe（II）。我们研究了这些基因的转录丰度作为铁配额（Q（Fe））的函数。铁还原酶的转录是丰富的两个物种（15%-60%的肌动蛋白）在低Q（Fe）和下调5- 35倍，在高Q（Fe），这表明Fe（III）的减少是一种常见的，可诱导的策略，在海洋硅藻铁收购。铁营养状态对T.的表达，但我们没有检测到显着差异的铜（Cu）含铁氧化酶。TpNRAMP表现出最显着的调节Q（Fe），这表明在细胞铁运输中的作用，无论是细胞表面吸收或液泡动员。我们无法在三角褐指藻基因组中鉴定铁氧化酶或通透酶同源物。T. P. tricornutum中似乎完全缺失的P. tricornutum和P. tricornutum似乎有一个有效的系统来获得Fe '的发现表明，不同的（和未表征的）Fe吸收系统可能在硅藻组合中起作用。硅藻之间不同的吸收系统可能提供了一个机制的基础生态位分化方面的铁在海洋中的可用性。
The centric diatom Thalassiosira pseudonana Hasle et Heimdal and the pennate diatom Phaeodactylum tricornutum Bohlin possess genes with translated sequences homologous to high-affinity ferric reductases present in model organisms. Thalassiosira pseudonana also possesses putative genes for membrane-bound ferroxidase (TpFET3) and two highly similar iron (Fe) permeases (TpFTR1 and TpFTR2), as well as a divalent metal (M2+) transporter belonging to the NRAMP superfamily (TpNRAMP). In baker's yeast, the ferroxidase-permease complex transports Fe(ll) produced by reductases. We investigated transcript abundances of these genes as a function of Fe quota (Q(Fe)). Ferric reductase transcripts are abundant in both species (15%-60% of actin) under low Q(Fe) and are down-regulated by 5- to 35-fold at high Q(Fe), suggesting Fe(III) reduction is a common, inducible strategy for Fe acquisition in marine diatoms. Permease transcript abundance was regulated by Fe status in T. pseudonana, but we did not detect significant differences in expression of the copper (Cu)-containing ferroxidase. TpNRAMP showed the most dramatic regulation by Q(Fe), suggesting a role in cellular Fe transport in either cell-surface uptake or vacuolar mobilization. We could not identify ferroxidase or permease homologues in the P. tricornutum genome. The up-regulation of genes in T. pseudonana that appear to be missing altogether from P. tricornutum as well as the finding that P. tricornutum seems to have an efficient system to acquire Fe', suggest that diverse (and uncharacterized) Fe-uptake systems may be at play within diatom assemblages. Different uptake systems among diatoms may provide a mechanistic basis for niche differentiation with respect to Fe availability in the ocean.