title: Genetic construction and properties of a diphtheria toxin-related substance P fusion protein: in vitro destruction of cells bearing substance P receptors.
abstract: We have genetically replaced the native receptor binding domain of diphtheria toxin with an extended form of substance P (SP): SP-glycine (SP-Gly). The resulting fusion protein, DAB389SP-Gly, is composed of the catalytic and transmembrane domains of diphtheria toxin genetically coupled to SP-Gly. Because native SP requires a C-terminal amide moiety to bind with high affinity to the SP receptor, the precursor form of the fusion toxin, DAB389SP-Gly, was converted to DAB389SP by treatment with peptidylglycine-alpha-amidating monooxygenase. We demonstrate that following conversion, DAB389SP is selectively cytotoxic for cell lines that express either the rat or the human SP receptor. We also demonstrate that the cytotoxic action of DAB389SP is mediated via the SP receptor and dependent upon passage through an acidic compartment. To our knowledge, this is the first reported use of a neuropeptide as the targeting ligand for a fusion toxin; and the first instance in which an inactive precursor form of a fusion toxin is converted to the active form by a posttranslational modification.
authors.affiliation: Evans Department of Clinical Research, Boston University Medical Center Hospital, Boston, MA 02118, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Fisher
authors.forename: J A
authors.initials: JA
authors.lastname: Sutherland
authors.forename: J E
authors.initials: JE
authors.lastname: Krause
authors.forename: J R
authors.initials: JR
authors.lastname: Murphy
authors.forename: S E
authors.initials: SE
authors.lastname: Leeman
authors.forename: J C
authors.initials: JC
authors.lastname: vanderSpek
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D016466:CHO Cells; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D003001:Cloning, Molecular; D006224:Cricetinae; D004167:Diphtheria Toxin / Q000096:biosynthesis* / Q000633:toxicity*; D004926:Escherichia coli; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D051381:Rats; D018040:Receptors, Neurokinin-1 / Q000096:biosynthesis / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000633:toxicity; D013373:Substance P / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism / Q000633:toxicity; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D004167:Diphtheria Toxin; D018040:Receptors, Neurokinin-1; D011993:Recombinant Fusion Proteins; D013373:Substance P; C046072:substance P, Gly(12)-