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Proc Natl Acad Sci U S A. 2014 Dec 16;111(50):E5480-7. doi: 10.1073/pnas.1421545111. Epub 2014 Dec 2.

Evolution of a plant-specific copper chaperone family for chloroplast copper homeostasis.

Author information

1
Department of Chemistry and Biochemistry, and.
2
Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA 01609.
3
Department of Chemistry and Biochemistry, and Institute of Genomics and Proteomics, University of California, Los Angeles, CA 90095; and sabeeha@chem.ucla.edu.

Abstract

Metallochaperones traffic copper (Cu(+)) from its point of entry at the plasma membrane to its destination. In plants, one destination is the chloroplast, which houses plastocyanin, a Cu-dependent electron transfer protein involved in photosynthesis. We present a previously unidentified Cu(+) chaperone that evolved early in the plant lineage by an alternative-splicing event of the pre-mRNA encoding the chloroplast P-type ATPase in Arabidopsis 1 (PAA1). In several land plants, recent duplication events created a separate chaperone-encoding gene coincident with loss of alternative splicing. The plant-specific Cu(+) chaperone delivers Cu(+) with specificity for PAA1, which is flipped in the envelope relative to prototypical bacterial ATPases, compatible with a role in Cu(+) import into the stroma and consistent with the canonical catalytic mechanism of these enzymes. The ubiquity of the chaperone suggests conservation of this Cu(+)-delivery mechanism and provides a unique snapshot into the evolution of a Cu(+) distribution pathway. We also provide evidence for an interaction between PAA2, the Cu(+)-ATPase in thylakoids, and the Cu(+)-chaperone for Cu/Zn superoxide dismutase (CCS), uncovering a Cu(+) network that has evolved to fine-tune Cu(+) distribution.

KEYWORDS:

Arabidopsis thaliana; Atx1; Cu-transfer; inner envelope; metal transporter

PMID:
25468978
PMCID:
PMC4273408
DOI:
10.1073/pnas.1421545111
[Indexed for MEDLINE]
Free PMC Article

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