Institute for Horticultural Plants, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, People's Republic of China.
Mol Biol Rep. 2013 Feb;40(2):1499-504. doi: 10.1007/s11033-012-2193-8. Epub 2012 Oct 19.
Malus xiaojinensis is an important, iron-efficient rootstock germplasm. Iron uptake is an elaborately controlled process in plant roots, involving specialized transporters. MxIRT1, a Fe(II) transporter gene of M. xiaojinensis, is homologous to other iron transporters at the amino acid level. In the current study, the plasmid pYES2.0-MxIRT1, containing MxIRT1 cDNA, was constructed and transformed into yeast mutants. The results indicated that it could reverse the phenotype of yeast strain DEY1453, an iron uptake mutant. Complementation tests suggested that it might not be a specific transporter, as it was able to restore the phenotypes of other yeast mutant strains, including Mn, Cu and Zn uptake mutants. The functions of the critical histidine residues in the His-box of MxIRT1 were tested by transforming mutant yeast strain DEY1453 with different His residues altered by directed mutagenesis. The His-box of MxIRT1 was found to be necessary for iron transport, with different histidine residues (H(1-4)) playing different roles in the transport.
小金海棠是一种重要的耐缺铁砧木资源。植物根系对铁的吸收是一个受到精细调控的过程，涉及到特定的转运蛋白。小金海棠的 Fe(II)转运蛋白基因 MxIRT1 在氨基酸水平上与其他铁转运蛋白同源。在本研究中，构建了含有 MxIRT1 cDNA 的质粒 pYES2.0-MxIRT1，并将其转化到酵母突变体中。结果表明，它可以逆转酵母菌株 DEY1453 的表型，该菌株是一个铁吸收突变体。互补测试表明，它可能不是一种特定的转运蛋白，因为它能够恢复其他酵母突变菌株的表型，包括 Mn、Cu 和 Zn 吸收突变体。通过用定向诱变改变不同的 His 残基，将突变的酵母菌株 DEY1453 转化为不同的 His 残基改变的突变酵母菌株，测试了 MxIRT1 中 His 盒中关键组氨酸残基的功能。发现 MxIRT1 的 His 盒对于铁的运输是必需的，不同的组氨酸残基（H(1-4)）在运输中发挥不同的作用。
