title: Farnesyl diphosphate synthase, the target for nitrogen-containing bisphosphonate drugs, is a peroxisomal enzyme in the model system Dictyostelium discoideum.
abstract: NBP (nitrogen-containing bisphosphonate) drugs protect against excessive osteoclast-mediated bone resorption. After binding to bone mineral, they are taken up selectively by the osteoclasts and inhibit the essential enzyme FDPS (farnesyl diphosphate synthase). NBPs inhibit also growth of amoebae of Dictyostelium discoideum in which their target is again FDPS. A fusion protein between FDPS and GFP (green fluorescent protein) was found, in D. discoideum, to localize to peroxisomes and to confer resistance to the NBP alendronate. GFP was also directed to peroxisomes by a fragment of FDPS comprising amino acids 1-22. This contains a sequence of nine amino acids that closely resembles the nonapeptide PTS2 (peroxisomal targeting signal type 2): there is only a single amino acid mismatch between the two sequences. Mutation analysis confirmed that the atypical PTS2 directs FDPS into peroxisomes. Furthermore, expression of the D. discoideum FDPS-GFP fusion protein in strains of Saccharomyces cerevisiae defective in peroxisomal protein import demonstrated that import of FDPS into peroxisomes was blocked in a strain lacking the PTS2-dependent import pathway. The peroxisomal location of FDPS in D. discoideum indicates that NBPs have to cross the peroxisomal membrane before they can bind to their target.
authors: Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
authors: James M
authors: JM
authors: Nuttall
authors: Ewald H
authors: EH
authors: Hettema
authors: Donald J
authors: DJ
authors: Watts
mesh_terms: D019386:Alendronate / Q000494:pharmacology; D000595:Amino Acid Sequence; D016384:Consensus Sequence; D004023:Dictyostelium / Q000235:genetics / Q000378:metabolism*; D004164:Diphosphonates / Q000494:pharmacology*; D004351:Drug Resistance; D051228:Geranyltranstransferase / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D000074437:Peroxisomal Targeting Signal 2 Receptor; D000074435:Peroxisome-Targeting Signal 1 Receptor; D020675:Peroxisomes / Q000378:metabolism*; D021381:Protein Transport; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D004164:Diphosphonates; D000074437:Peroxisomal Targeting Signal 2 Receptor; D000074435:Peroxisome-Targeting Signal 1 Receptor; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D051228:Geranyltranstransferase; D019386:Alendronate