Amino acid polymorphisms in strictly conserved domains of a P-type ATPase HMA5 are involved in the mechanism of copper tolerance variation in Arabidopsis
Amino acid polymorphisms in strictly conserved domains of a P-type ATPase HMA5 are involved in the mechanism of copper tolerance variation in Arabidopsis
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DOI：
10.1104/pp.108.119933
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发表时间：
2008-10-01
期刊：
影响因子：
7.4
通讯作者：
Koyama, Hiroyuki
中科院分区：
文献类型：
--
作者：
Kobayashi, Yuriko;Kuroda, Keishi;Koyama, Hiroyuki
铜（Cu）是植物营养的必需元素，但低浓度时会抑制根系的生长。拟南芥 (Arabidopsis thaliana) 种质对铜的耐受性各不相同。为了了解拟南芥铜耐受性的分子机制，我们进行了数量性状基因座（QTL）分析和种质研究。 1 号染色体上的一个主要 QTL (QTL1) 解释了兰茨贝格直立/佛得角群岛 (Ler/Cvi) 重组近交群体根部铜耐受性的 52% 表型变异。该 QTL 调节 Cu 易位能力并涉及 Cu 转运 P1B-1 型 ATP 酶 HMA5。与Ler等位基因相比，Cvi等位基因携带两个氨基酸取代，并且当通过使用T-DNA插入突变体的互补测定来判断时，Cvi等位基因在铜耐受性方面比Ler等位基因功能较差。使用嵌合 HMA5 蛋白对酵母 ccc2 突变体进行的互补分析表明，Cvi 等位基因的 N923T（在紧密保守的结构域 N(x)(6)YN(x)(4)P（其中前天冬酰胺被苏氨酸取代）中被鉴定）是 Cvi HMA5 等位基因功能障碍的原因。 Chisdra-2 中发现了另一个功能失调的 HMA5 等位基因，该等位基因表现出铜敏感性和铜从根到芽的易位能力低。在另一个严格保守的结构域 CPC(x)(6)P 中发现了 Chisdra-2 的独特氨基酸取代，其中后者的脯氨酸被亮氨酸取代。这些结果表明，拟南芥铜耐受性的部分变异是由铜转位ATP酶HMA5的功能完整性调节的，特别是几个严格保守基序中的氨基酸序列。
Copper (Cu) is an essential element in plant nutrition, but it inhibits the growth of roots at low concentrations. Accessions of Arabidopsis ( Arabidopsis thaliana) vary in their tolerance to Cu. To understand the molecular mechanism of Cu tolerance in Arabidopsis, we performed quantitative trait locus (QTL) analysis and accession studies. One major QTL on chromosome 1 (QTL1) explained 52% of the phenotypic variation in Cu tolerance in roots in a Landsberg erecta/Cape Verde Islands (Ler/ Cvi) recombinant inbred population. This QTL regulates Cu translocation capacity and involves a Cu-transporting P1B-1-type ATPase, HMA5. The Cvi allele carries two amino acid substitutions in comparison with the Ler allele and is less functional than the Ler allele in Cu tolerance when judged by complementation assays using a T-DNA insertion mutant. Complementation assays of the ccc2 mutant of yeast using chimeric HMA5 proteins revealed that N923T of the Cvi allele, which was identified in the tightly conserved domain N(x)(6)YN(x)(4)P (where the former asparagine was substituted by threonine), is a cause of dysfunction of the Cvi HMA5 allele. Another dysfunctional HMA5 allele was identified in Chisdra-2, which showed Cu sensitivity and low capacity of Cu translocation from roots to shoots. A unique amino acid substitution of Chisdra-2 was identified in another strictly conserved domain, CPC(x)(6)P, where the latter proline was replaced with leucine. These results indicate that a portion of the variation in Cu tolerance of Arabidopsis is regulated by the functional integrity of the Cu-translocating ATPase, HMA5, and in particular the amino acid sequence in several strictly conserved motifs.