Identification of the copper chaperone, CUC-1, in Caenorhabditis elegans: tissue specific co-expression with the copper transporting ATPase, CUA-1.

A cDNA encoding a putative copper chaperone protein, CUC-1, was cloned from Caenorhabditis elegans. CUC-1 had the characteristic motifs of MTCXXC and KKTGK, and showed 49.3 and 39.1% sequence identity with yeast Atx1p and human HAH1, respectively. Expression of CUC-1 cDNA complemented a null atx1 mutant, the yeast copper chaperone gene, thus demonstrating that CUC-1 is a functional copper chaperone. Studies with transgenic worms indicated that cuc-1 and cua-1, which encodes the copper transporting ATPase, are expressed together in intestinal cells of adult and hypodermal cells in the larvae. cua-1 was also expressed in pharyngeal muscle but cuc-1 was not. These results suggest that CUC-1 and CUA-1 constitute a copper trafficking pathway similar to the yeast counterparts in intestinal and hypodermal cells, and CUA-1 may have a different function in pharyngeal muscle.