The Caenorhabditis elegans Y87G2A.14 Nudix hydrolase is a peroxisomal coenzyme A diphosphatase

Background: The number of Nudix hydrolase family members varies widely among different organisms. In order to understand the reasons for the particular spectrum possessed by a given organism, the substrate specificity and function of different family members must be established. Results: The Y87G2A.14 Nudix hydrolase gene product of Caenorhabditis elegans has been expressed as a thioredoxin fusion protein in Escherichia coli and shown to be a CoA diphosphatase with catalytic activity towards CoA and its derivatives. The products of CoA hydrolysis were 3',5'-ADP and 4'-phosphopantetheine with K-m and k(cat) values of 220 mu M and 13.8 s(-1) respectively. CoA esters yielded 3', 5'-ADP and the corresponding acyl-phosphopantetheine. Activity was optimal at pH 9.5 with 5 mM Mg2+ and fluoride was inhibitory with a K-i of 3 mu M. The Y87G2A.14 gene product has a potential C-terminal tripeptide PTS1 peroxisomal targeting signal-SKI. By fusing a Y87G2A.14 cDNA to the C-terminus of yeast-enhanced green fluorescent protein, the enzyme appeared to be targeted to peroxisomes by the SKI signal when transfected into yeast cells. Deletion of SKI abolished specific targeting. Conclusions: The presence of related sequences with potential PTS1 or PTS2 peroxisomal targeting signals in other organisms suggests a conserved peroxisomal function for the CoA diphosphatase members of this group of Nudix hydrolases.