title: Insecticidal activity of a recombinant knottin peptide from Loxosceles intermedia venom and recognition of these peptides as a conserved family in the genus.
abstract: Loxosceles intermedia venom comprises a complex mixture of proteins, glycoproteins and low molecular mass peptides that act synergistically to immobilize envenomed prey. Analysis of a venom-gland transcriptome from L. intermedia revealed that knottins, also known as inhibitor cystine knot peptides, are the most abundant class of toxins expressed in this species. Knottin peptides contain a particular arrangement of intramolecular disulphide bonds, and these peptides typically act upon ion channels or receptors in the insect nervous system, triggering paralysis or other lethal effects. Herein, we focused on a knottin peptide with 53 amino acid residues from L. intermedia venom. The recombinant peptide, named U2-sicaritoxin-Li1b (Li1b), was obtained by expression in the periplasm of Escherichia coli. The recombinant peptide induced irreversible flaccid paralysis in sheep blowflies. We screened for knottin-encoding sequences in total RNA extracts from two other Loxosceles species, Loxosceles gaucho and Loxosceles laeta, which revealed that knottin peptides constitute a conserved family of toxins in the Loxosceles genus. The insecticidal activity of U2-SCTX-Li1b, together with the large number of knottin peptides encoded in Loxosceles venom glands, suggests that studies of these venoms might facilitate future biotechnological applications of these toxins.
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, Curitiba, Paraná, Brazil.
authors.forename: F H
authors.initials: FH
authors.lastname: Matsubara
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, Curitiba, Paraná, Brazil.|Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD, Australia.
authors.forename: G O
authors.initials: GO
authors.lastname: Meissner
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD, Australia.
authors.forename: V
authors.initials: V
authors.lastname: Herzig
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, Curitiba, Paraná, Brazil.
authors.forename: H C
authors.initials: HC
authors.lastname: Justa
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, Curitiba, Paraná, Brazil.
authors.forename: B C L
authors.initials: BC
authors.lastname: Dias
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, Curitiba, Paraná, Brazil.
authors.forename: D
authors.initials: D
authors.lastname: Trevisan-Silva
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, Curitiba, Paraná, Brazil.
authors.forename: L H
authors.initials: LH
authors.lastname: Gremski
authors.affiliation: Health and Biological Science Institute, Catholic University of Parana, Prado Velho, Curitiba, Paraná, Brazil.
authors.forename: W
authors.initials: W
authors.lastname: Gremski
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, Curitiba, Paraná, Brazil.
authors.forename: A
authors.initials: A
authors.lastname: Senff-Ribeiro
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, Curitiba, Paraná, Brazil.
authors.forename: O M
authors.initials: OM
authors.lastname: Chaim
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD, Australia.
authors.forename: G F
authors.initials: GF
authors.lastname: King
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, Curitiba, Paraná, Brazil.
authors.forename: S S
authors.initials: SS
authors.lastname: Veiga
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D063287:Brown Recluse Spider / Q000235:genetics* / Q000378:metabolism; D017124:Conserved Sequence; D057771:Cystine-Knot Miniproteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D004175:Diptera; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli; D007306:Insecticides / Q000032:analysis*; D008969:Molecular Sequence Data; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry*; D020543:Proteome; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D013111:Spider Venoms / Q000737:chemistry*; D018675:Toxicity Tests; D059467:Transcriptome
chemical_list: D057771:Cystine-Knot Miniproteins; D007306:Insecticides; D020543:Proteome; D011994:Recombinant Proteins; D013111:Spider Venoms; C055161:loxosceles venom; D010727:Phosphoric Diester Hydrolases
keywords: Loxosceles; bioinsecticide; brown spider; inhibitor cystine knot; knottin; venom