A specific transporter for iron(III)-phytosiderophore in barley roots
A specific transporter for iron(III)-phytosiderophore in barley roots
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DOI：
10.1111/j.1365-313x.2006.02714.x
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发表时间：
2006-05-01
期刊：
影响因子：
7.2
通讯作者：
Iwashita, T
中科院分区：
文献类型：
--
作者：
Murata, Y;Ma, JF;Iwashita, T
禾科植物的铁获取的特点是铁螯合植物铁载体mugineic acid （MA）的合成和分泌，以及铁(III)-植物铁载体复合物的特定吸收系统。我们在大麦中发现了一个特异性编码铁-植物铁素载体（HvYS1）的基因，大麦是禾本科植物中最耐缺铁的物种。HvYS1编码678个氨基酸的多肽，与ZmYS1具有72.7%的同源性，ZmYS1是玉米中第一个被鉴定为铁(III)-植物铁载体的蛋白。Real-time RT-PCR分析显示，HvYS1基因主要在根中表达，缺铁条件下表达增强。对缺铁大麦根进行原位杂交分析，发现HvYS1 mRNA定位于表皮根细胞。此外，抗hvys1多克隆抗体免疫组织染色显示与mRNA相同的定位。HvYS1在含铁(III)-MA而不含铁-烟胺（NA）的培养基上补充了铁摄取缺陷的酵母菌株。HvYS1在爪蟾卵母细胞中的表达对金属和配体均具有严格的特异性：HvYS1仅运输与植物铁素螯合的铁（III）。HvYS1的定位和底物特异性与ZmYS1不同，表明HvYS1是大麦根系铁(III)-植物铁素载体的特异性转运体，参与大麦根系从土壤中获取初级铁。
Iron acquisition of graminaceous plants is characterized by the synthesis and secretion of the iron-chelating phytosiderophore, mugineic acid (MA), and by a specific uptake system for iron(III)-phytosiderophore complexes. We identified a gene specifically encoding an iron-phytosiderophore transporter (HvYS1) in barley, which is the most tolerant species to iron deficiency among graminaceous plants. HvYS1 was predicted to encode a polypeptide of 678 amino acids and to have 72.7% identity with ZmYS1, a first protein identified as an iron(III)-phytosiderophore transporter in maize. Real-time RT-PCR analysis showed that the HvYS1 gene was mainly expressed in the roots, and its expression was enhanced under iron deficiency. In situ hybridization analysis of iron-deficient barley roots revealed that the mRNA of HvYS1 was localized in epidermal root cells. Furthermore, immunohistological staining with anti-HvYS1 polyclonal antibody showed the same localization as the mRNA. HvYS1 functionally complemented yeast strains defective in iron uptake on media containing iron(III)-MA, but not iron-nicotianamine (NA). Expression of HvYS1 in Xenopus oocytes showed strict specificity for both metals and ligands: HvYS1 transports only iron(III) chelated with phytosiderophore. The localization and substrate specificity of HvYS1 is different from those of ZmYS1, indicating that HvYS1 is a specific transporter for iron(III)-phytosiderophore involved in primary iron acquisition from soil in barley roots.