Publications

• Isolation and characterization of a prenylcysteine lyase from bovine brain.

  Zhang L., Tschantz W.R., Casey P.J.

  Prenylated proteins contain one of two isoprenoid lipids, either the 15-carbon farnesyl or the 20-carbon geranylgeranyl, covalently attached to cysteine residues at or near their C terminus. The cellular abundance of prenylated proteins, which can comprise up to 2% of total cellular protein, raise ... >> More

  Prenylated proteins contain one of two isoprenoid lipids, either the 15-carbon farnesyl or the 20-carbon geranylgeranyl, covalently attached to cysteine residues at or near their C terminus. The cellular abundance of prenylated proteins, which can comprise up to 2% of total cellular protein, raises the question of how cells dispose of prenylcysteines produced during the normal turnover of prenylated proteins. We have identified and characterized a novel enzyme, which we term prenylcysteine lyase, that is capable of cleaving the thioether bond of prenylcysteines. The enzyme was isolated from bovine brain membranes and exhibits an apparent molecular mass of 63 kDa. The enzyme did not require NADPH as cofactor for prenylcysteine degradation, thus distinguishing it from cytochrome P450- and flavin-containing monooxygenases that catalyze S-oxidation of thioethers. Purified prenylcysteine lyase shows similar kinetics in utilization of both farnesylcysteine and geranylgeranylcysteine as substrates, although Vmax is 2-fold higher with the former compound. Interaction of prenylcysteine substrates with the enzyme requires that they possess a free amino group; N-acetylated prenylcysteines and prenyl peptides are not substrates. These findings suggest that prenylcysteine lyase is a specific enzyme involved in prenylcysteine metabolism in mammalian cells, most likely comprising the final step in the degradation of prenylated proteins. << Less

  J. Biol. Chem. 272:23354-23359(1997) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Lysosomal prenylcysteine lyase is a FAD-dependent thioether oxidase.

  Tschantz W.R., Digits J.A., Pyun H.J., Coates R.M., Casey P.J.

  Prenylated proteins contain either a 15-carbon farnesyl or a 20-carbon geranylgeranyl isoprenoid covalently attached via a thioether bond to a cysteine residue at or near their C terminus. As prenylated proteins comprise up to 2% of the total protein in eukaryotic cells, and the thioether bond is ... >> More

  Prenylated proteins contain either a 15-carbon farnesyl or a 20-carbon geranylgeranyl isoprenoid covalently attached via a thioether bond to a cysteine residue at or near their C terminus. As prenylated proteins comprise up to 2% of the total protein in eukaryotic cells, and the thioether bond is a stable modification, their degradation raises a metabolic challenge to cells. A lysosomal enzyme termed prenylcysteine lyase has been identified that cleaves prenylcysteines to cysteine and an unidentified isoprenoid product. Here we show that the isoprenoid product of prenylcysteine lyase is the C-1 aldehyde of the isoprenoid moiety (farnesal in the case of C-15). The enzyme requires molecular oxygen as a cosubstrate and utilizes a noncovalently bound flavin cofactor in an NAD(P)H-independent manner. Additionally, a stoichiometric amount of hydrogen peroxide is produced during the reaction. These surprising findings indicate that prenylcysteine lyase utilizes a novel oxidative mechanism to cleave thioether bonds and provide insight into the unique role this enzyme plays in the cellular metabolism of prenylcysteines. << Less

  J. Biol. Chem. 276:2321-2324(2001) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Stereospecificity and kinetic mechanism of human prenylcysteine lyase, an unusual thioether oxidase.

  Digits J.A., Pyun H.J., Coates R.M., Casey P.J.

  Prenylated proteins contain either a 15-carbon farnesyl or a 20-carbon geranylgeranyl isoprenoid covalently attached to cysteine residues at or near their C terminus. The cellular abundance of prenylated proteins, as well as the stability of the thioether bond, poses a metabolic challenge to cells ... >> More

  Prenylated proteins contain either a 15-carbon farnesyl or a 20-carbon geranylgeranyl isoprenoid covalently attached to cysteine residues at or near their C terminus. The cellular abundance of prenylated proteins, as well as the stability of the thioether bond, poses a metabolic challenge to cells. A lysosomal enzyme termed prenylcysteine lyase has been identified that degrades a variety of prenylcysteines. Prenylcysteine lyase is a FAD-dependent thioether oxidase that produces free cysteine, an isoprenoid aldehyde, and hydrogen peroxide as products of the reaction. Here we report initial studies of the kinetic mechanism and stereospecificity of this unusual enzyme. We utilized product and dead end inhibitors of prenylcysteine lyase to probe the kinetic mechanism of the multistep reaction. The results with these inhibitors, together with those of other experiments, suggest that the reaction catalyzed by prenylcysteine lyase proceeds through a sequential mechanism. The reaction catalyzed by the enzyme is stereospecific, in that the pro-S hydride of the farnesylcysteine is transferred to FAD to initiate the reaction. With (2R,1'S)-[1'-(2)H(1)]farnesylcysteine as a substrate, a primary deuterium isotope effect of 2 was observed on the steady state rate. However, the absence of an isotope effect on an observed pre-steady-state burst of hydrogen peroxide formation implicates a partially rate-determining proton transfer after a relatively fast C-H (C-D) bond cleavage step. Furthermore, no pre-steady-state burst of cysteine was observed. The finding that the rate of cysteine formation was within 2-fold of the steady-state k(cat) value indicates that cysteine production is one of the primary rate-limiting steps in the reaction. These results provide substantial new information on the catalytic mechanism of prenylcysteine lyase. << Less

  J. Biol. Chem. 277:41086-41093(2002) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.