Genomic structure of mouse copper chaperone, COX17

Coxl7p was first cloned as a cytoplasmic copper chaperone from yeast mutant and recent works suggested the existence of mammalian homologues. Previous report has shown that a gel filtration fraction of heart extract containing porcine Coxl7p peptide promoted the survival of NIH3T3 fibroblast cells. In the present study, we first cloned DNA fragments of the mouse COX17 gene. The mouse COX17 spans approximately 6kb and consists of three exons. It was mapped to the center of chromosome 16, using a radiation hybrid-mapping panel. The major transcription start site is 80 bp upstream of the ATG initiation codon as determined by rapid amplification of cDNA ends (5'-RACE) analysis. Two potential polyadenylation sites are 3233 and 3293 bp downstream of the termination codon, respectively. Transient transfection of reporter plasmids containing portions of the mouse COX17 5'-flanking region into AtT-20 and NIH3T3 cells allowed the localization of the essential promoter to a 0.8 kb region upstream of the transcription starting site. Furthermore, the transfected luciferase activity was much higher in AtT-20 than NIH3T3. According to sequence analysis of the approximately 0.8kb 5'-flanking region, GC rich segments including consensus sequences for binding of the transcription factor Sp1, but no TATA/CAAT boxes, exist in the region of the transcription start site. Besides the GC box, binding sites for NRF-1 and 2 known as specific transcription factors for COX subunits are also localized around the transcription starting site.