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Evolution Of A Plant-Specific Copper Chaperone Family For Chloroplast Copper Homeostasis., José Argüello, Crysten Blaby-Haas, Teresita Padilla-Benavides, Roland Stube, Sabeeha Merchant

José M. Argüello

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 …