AtCOX10, a protein required for heme a synthesis during COX assembly, is involved in plant embryogenesis and senescence.

MANSILLA, NATANAEL; GARCÍA LUCILA; GONZALEZ, DANIEL; WELCHEN, ELINA

Congreso; 8vo International Conference in Plant Mitochondrial Biology; 2013

Cytochrome c oxidase (CcO) biogenesis requires more than 20 accessory proteins implicated, among other processes, in copper and heme a insertion. COX10, a farnesyltransferase that catalyzes the conversion of heme b to heme o, is the limiting factor in heme a biosynthesis and is essential for its insertion in the COX1 subunit in yeast. By complementation analysis of a yeast cox10 mutant, we obtained information about the functionality of the putative Arabidopsis COX10 protein. We observed that COX10 is able to restore growth on non-fermentable carbon sources when was expressed in a yeast cox10 null mutant. We have also studied Arabidopsis mutant plants with a T-DNA insertion in the coding region of the AtCOX10 gene. Segregation analysis of heterozygote mutants demonstrated that it was not possible to obtain knockout plants. Siliques of mutant plants contained 25% abnormal seeds with embryos arrested at early stages of development, suggesting that COX10 function is essential during plant embryogenesis. According to this, COX10 promoter-GUS expression was observed in embryos of the same age, and normal embryogenesis was restored in Arabidopsis homozygous mutants complemented with AtCOX10 expressed under its own promoter or the constitutive 35SCaMV promoter. In addition, heterozygous mutants reached senescence before wild-type plants, suggesting a function of COX10 in this process.