title: Isolation of two insecticidal toxins from venom of the Australian theraphosid spider Coremiocnemis tropix.
abstract: Sheep flystrike is caused by parasitic flies laying eggs on soiled wool or open wounds, after which the hatched maggots feed on the sheep flesh and often cause large lesions. It is a significant economic problem for the livestock industry as infestations are difficult to control due to ongoing cycles of larval development into flies followed by further egg laying. We therefore screened venom fractions from the Australian theraphosid spider Coremiocnemis tropix to identify toxins active against the sheep blowfly Lucilia cuprina, which is the primary cause of flystrike in Australia. This screen led to isolation of two insecticidal peptides, Ct1a and Ct1b, that are lethal to blowflies within 24 h of injection. The primary structure of these peptides was determined using a combination of Edman degradation and sequencing of a C. tropix venom-gland transcriptome. Ct1a and Ct1b contain 39 and 38 amino acid residues, respectively, including six cysteine residues that form three disulfide bonds. Recombinant production in bacteria (Escherichia coli) resulted in low yields of Ct1a whereas solid-phase peptide synthesis using native chemical ligation produced sufficient quantities of Ct1a for functional analyses. Synthetic Ct1a had no effect on voltage-gated sodium channels from the American cockroach Periplanata americana or the German cockroach Blattella germanica, but it was lethal to sheep blowflies with an LD50of 1687 pmol/g.
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Maria P
authors: MP
authors: Ikonomopoulou
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Jennifer J
authors: JJ
authors: Smith
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Volker
authors: V
authors: Herzig
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Sandy S
authors: SS
authors: Pineda
authors: School of Life Sciences, University of Technology Sydney, NSW 2007, Australia.
authors: Sławomir
authors: S
authors: Dziemborowicz
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Sing-Yan
authors: SY
authors: Er
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Thomas
authors: T
authors: Durek
authors: Department of Physiology & Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA.
authors: John
authors: J
authors: Gilchrist
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors: Paul F
authors: PF
authors: Alewood
authors: School of Life Sciences, University of Technology Sydney, NSW 2007, Australia.
authors: Graham M
authors: GM
authors: Nicholson
authors: Department of Physiology & Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA.
authors: Frank
authors: F
authors: Bosmans
authors: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia. Electronic address: glenn.king@imb.uq.edu.au.
authors: Glenn F
authors: GF
authors: King
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D002851:Chromatography, High Pressure Liquid; D004175:Diptera; D007306:Insecticides / Q000302:isolation & purification*; D013058:Mass Spectrometry; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D012756:Sheep / Q000469:parasitology; D013111:Spider Venoms / Q000737:chemistry*; D018675:Toxicity Tests; D059467:Transcriptome
chemical_list: D060829:Arthropod Proteins; D007306:Insecticides; D013111:Spider Venoms
keywords: Bioinsecticide; Coremiocnemis tropix; Flystrike; Insecticidal peptide; Lucilia cuprina; Spider venom