Cloning, expression, and cellular localization of a human prenylcysteine lyase

Prenylated proteins contain either a 15-carbon farnesyl or 20-carbon gerany lgeranyl isoprenoid covalently attached to cysteine residues at or near the ir C terminus. These proteins constitute up to 2% of total cellular protein in eukaryotic cells. The degradation of prenylated proteins raises a metab olic challenge to the cell, because the thioether bond of the modified cyst eine is quite stable. We recently identified and isolated an enzyme termed prenylcysteine lyase that cleaves the prenylcysteine to free cysteine and a n isoprenoid product (Zhang, L., Tschantz, W, R,, and Casey, P, J, (1997) J . Biol. Chem. 272, 23354-23359), To facilitate the molecular characterizati on of this enzyme, its cloning was undertaken. Overlapping cDNA clones enco ding the complete coding sequence of this enzyme were obtained from a human cDNA library. The open reading frame of the gene encoding prenylcysteine l yase is 1515 base pairs and has a nearly ubiquitous expression pattern with a message size of 6 kilobase pairs. Recombinant prenylcysteine lyase was p roduced in a baculovirus-Sf9 expression system. Analysis of both the recomb inant and native enzyme revealed that the enzyme is glycosylated and contai ns a signal peptide that is cleaved during processing. Additionally, the su bcellular localization of this enzyme was determined to be lysosomal. These findings strengthen the notion that prenylcysteine lyase plays an importan t role in the final step in the degradation of prenylated proteins and will allow further physiological and biochemical characterization of this enzym e.