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

Abstract

BackgroundThe 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.ResultsThe 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 Km and kcat values of 220 μM 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 Ki of 3 μM. 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.ConclusionsThe 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.