The Arabidopsis heavy metal P‐type ATPase HMA5 interacts with metallochaperones and functions in copper detoxification of roots

Abstract

SummarySince copper (Cu) is essential in key physiological oxidation reactions, organisms have developed strategies for handling Cu while avoiding its potentially toxic effects. Among the tools that have evolved to cope with Cu is a network of Cu homeostasis factors such as Cu-transporting P-type ATPases that play a key role in transmembrane Cu transport. In this work we present the functional characterization of an Arabidopsis Cutransporting P-type ATPase, denoted heavy metal ATPase 5 (HMA5), and its interaction with Arabidopsis metallochaperones. HMA5 is primarily expressed in roots, and is strongly and specifically induced by Cu in whole plants. We have identified and characterized plants carrying two independent T-DNA insertion alleles, hma5-1 and hma5-2. Both mutants are hypersensitive to Cu but not to other metals such as iron, zinc or cadmium. Interestingly, root tips from Cu-treated hma5 mutants exhibit a wave-like phenotype at early stages and later on main root growth completely arrests whereas lateral roots emerge near the crown. Accordingly, these lines accumulate Cu in roots to a greater extent than wild-type plants under Cu excess. Finally, yeast two-hybrid experiments demonstrate that the metal-binding domains of HMA5 interact with Arabidopsis ATX1-like Cu chaperones, and suggest a regulatory role for the plant-specific domain of the CCH Cu chaperone. Based on these findings, we propose a role for HMA5 in Cu compartmentalization and detoxification.

Natural Variation of Root Traits: From Development to Nutrient Uptake

“…A large fraction of the variation in copper tolerance in Arabidopsis, which was evaluated by measurements of root growth, was attributed to the heavy metal-transporting P-type adenosine triphosphatase5 (HMA5) adenosine triphosphatase (Kobayashi et al, 2008). This is consistent with the involvement of HMA5 in root-to-shoot transport (Andrés-Colás et al, 2006).…”

Comparison of global responses to mild deficiency and excess copper levels in Arabidopsis seedlings

“…thaliana plants, ecotype Col 0, and spl7 knockout plants 10 were grown as previously described. 33 The MS 1/2 medium (MS) 30 61 Chlorophyll content was determined by the trichlorometric method. 62 Gene expression by semi-quantitative and real-time quantitative PCR Total RNA was isolated from A. thaliana seedlings with Trizol Reagent (Ambion).…”

A Member of the Heavy Metal P-Type ATPase OsHMA5 Is Involved in Xylem Loading of Copper in Rice

“…The closest homolog of OsHMA5 in A. thaliana, AtHMA5, has been reported to be involved in Cu detoxification (Andrés-Colás et al, 2006;Kobayashi et al, 2008). AtHMA5 was mainly expressed in roots and flowers, and its expression was greatly up-regulated by high Cu concentrations (Andrés-Colás et al, 2006).…”

“…Since AtHMA5, a homolog of OsHMA5 in A. thaliana, is involved in Cu detoxification (Andrés-Colás et al, 2006;Kobayashi et al, 2008), we compared the Cu tolerance at different Cu concentrations between the wildtype rice and OsHMA5 knockout lines by measuring root elongation (24 h). The root elongation was inhibited similarly by different Cu concentrations in wild-type rice and two mutants.…”

“…AtHMA2 and AtHMA4 localized at the pericycle are partially redundant and responsible for the release of Zn into the xylem (xylem loading) as well as Cd (Hussain et al, 2004;Verret et al, 2004;, while AtHMA3 localized at the tonoplast plays a role in the detoxification of Zn/Cd/cobalt/Pb by mediating them into the vacuole (Morel et al, 2009;Chao et al, 2012). On the other hand, AtHMA5 is involved in the Cu translocation from roots to shoots or Cu detoxification of roots (Andrés-Colás et al, 2006;Kobayashi et al, 2008). AtHMA6 (PAA1, for P-type ATPase of Arabidopsis1) localized at the chloroplast periphery has been proposed to transport Cu over the chloroplast envelope, whereas AtHMA8 (PAA2) localized at the thylakoid membranes most likely transports Cu into the thylakoid lumen to supply plastocyanin (Shikanai et al, 2003;Abdel-Ghany et al, 2005).…”