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

Abstract

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