AtCOX17, an Arabidopsis Homolog of the Yeast Copper Chaperone COX17

Abstract

We have identified a new plant gene, AtCOX17, encoding a protein that shares sequence similarity to COX17, a Cu-binding protein from yeast (Saccharomyces cerevisiae) and vertebrates that mediates the delivery of Cu to the mitochondria for the assembly of a functional cytochrome oxidase complex. The newly characterized Arabidopsis protein has six Cys residues at positions corresponding to those known to coordinate Cu binding in the yeast homolog. Moreover, we show that the Arabidopsis COX17 cDNA complements a COX17 mutant of yeast restoring the respiratory deficiency associated with that mutation. These two lines of evidence indicate that the plant protein identified here is a functional equivalent of yeast COX17 and might serve as a Cu delivery protein for the plant mitochondria. COX17 was identified by investigating the hypersensitive response-like necrotic response provoked in tobacco (Nicotiana tabacum) leaves after harpin inoculation. AtCOX17 expression was activated by high concentrations of Cu, bacterial inoculation, salicylic acid treatment, and treatments that generated NO and hydrogen peroxide. All of the conditions inducing COX17 are known to inhibit mitochondrial respiration and to produce an increase of reactive oxygen species, suggesting that gene induction occurs in response to stress situations that interfere with mitochondrial function.

Knock-down of the COX3 and COX17 gene expression of cytochrome c oxidase in the unicellular green alga Chlamydomonas reinhardtii

“…In Arabidopsis thaliana, the abundance of the COX17 mRNA is increased after short treatments with metals (Attallah et al 2007;Balandin and Castresana 2002). To determine if a similar situation is found in Chlamydomonas, exponentially growing cells were treated with a non-inhibiting concentration of CuSO 4 (250 lM, 4 h) or CdCl 2 (250 lM, 2 h; Hanikenne et al 2005).…”

“…Among them, Cox11, Cox17, Cox19, Cox23, Sco1, and Sco2 proteins play a role in copper delivery to cytochrome c oxidase (Barros et al 2004;Horng et al 2004;Leary et al 2004;Nobrega et al 2002) and homologues have been found in the nuclear genome of Arabidopsis and Chlamydomonas (Cardol et al 2008). Two COX17 genes are present in the Arabidopsis genome and one of them was shown to encode a protein able to complement a cox17 yeast mutant (Balandin and Castresana 2002). Moreover, RNA abundance of both genes was induced by compounds or factors that produce stress, like metals or pathogens, which may indicate a relevant role of this protein in the biogenesis of cytochrome c oxidase to replace damaged forms of the enzyme or a more general role in the plant stress response (Attallah et al 2007;Balandin and Castresana 2002).…”

“…Two COX17 genes are present in the Arabidopsis genome and one of them was shown to encode a protein able to complement a cox17 yeast mutant (Balandin and Castresana 2002). Moreover, RNA abundance of both genes was induced by compounds or factors that produce stress, like metals or pathogens, which may indicate a relevant role of this protein in the biogenesis of cytochrome c oxidase to replace damaged forms of the enzyme or a more general role in the plant stress response (Attallah et al 2007;Balandin and Castresana 2002).…”

Transporters, chaperones, and P-type ATPases controlling grapevine copper homeostasis

“…The COX17 chaperone shares sequence homologous to COX17 from yeast that might mediate the delivery of Cu to the mitochondria for the assembly of a functional cytochrome c oxidase complex and cytosolic enzymes such as Cu/Zn superoxide dismutase (Cu/ZnSOD). In this manner, COX17 would contribute to the increase in activity of specific enzymes that are required to preserve organelle functionality in a number of biotic and abiotic stress situations (Balandin and Castresana 2002). The CCS gene, homolog of the yeast Ccs1p/Lys7p gene, had been identified as a key factor integrating copper into copper/zinc superoxide dismutase (Cu/ZnSOD) by a protein-protein interaction.…”

Gene Expression: A Review on Methods for the Study of Defense-Related Gene Differential Expression in Plants

“…In plants, three members (CCH, CCS and COX17) of this family have been identified and classified [23]. Copper is involved in several physiological processes, including those related to defense, such as oxidative stress and the synthesis of receptors for the plant hormone ethylene [24,25]. Another example is cytochrome P450, which is involved in cellular detoxification processes such as the detoxification of herbicides and the biosynthesis of cutin and hormones such as brassinosteroids [26].…”