Copper homeostasis in plants: role of two Arabidopsis metal chaperones involved in COX biogenesis.

WELCHEN, ELINA; ATTALLAH, CAROLINA.; GONZALEZ, DANIEL H.

Congreso; 45 Annual Meeting Argentine Society for Biochemistry and Molecular Biology XLV; 2009

In higher plants, copper (Cu) plays key roles in the photosynthetic and respiratory electron transport chains and is involved in crucial processes including ethylene perception, cell wall metabolism and oxidative stress protection. Cu deficiency induces plant chlorosis, mostly affecting young leaves and reproductive organs. We studied two Arabidopis proteins, AtCOX19 (At1g66590) and AtCOX17-1 (At3g15352), putative homologues of yeast metal chaperones involved in Cu delivery for cytochrome c oxidase (COX) biogenesis. Arabidospsis plants overexpressing AtCOX19 and AtCOX17-1 show a Cu deficiency phenotype, with severe disorders at the vegetative and reproductive stages, affecting normal pollen development and fertility. Although the Cu levels in 2-week-old seedlings measured by atomic absorption spectroscopy are comparable to those of wild-type, plants are Cu hipersensitive and exhibit decreased root length and reduced fresh weight, that is partially reverted by a copper-specific chelator. At the molecular level, overexpressing plants have higher expression levels of the stress responsive gene AOX1a, encoding the mitochondrial alternative oxidase, and altered expression levels of genes related with Cu metabolism. We conclude that the metal chaperones under study have a role in regulating cellular Cu homeostasis in addition to their known function in COX assembly.