title: Sphingomyelinase D in sicariid spider venom is a potent insecticidal toxin.
abstract: Spider venoms have evolved over hundreds of millions of years with a primary role of immobilizing prey. Sphingomyelinase D (SMase D) and homologs in the SicTox gene family are the most abundantly expressed toxic protein in venoms of Loxosceles and Sicarius spiders (Sicariidae). While SMase D is well known to cause dermonecrotic lesions in mammals, little work has investigated the bioactivity of this enzyme in its presumed natural role of immobilizing insect prey. We expressed and purified recombinant SMase D from Loxosceles arizonica (Laz-SMase D) and compared its enzymatic and insecticidal activity to that of crude venom. SMase D enzymatic activities of purified protein and crude venom from the same species were indistinguishable. In addition, SMase D and crude venom have comparable and high potency in immobilization assays on crickets. These data indicate that SMase D is a potent insecticidal toxin, the role for which it presumably evolved.
authors.affiliation: Department of Biology, Lewis & Clark College, Portland, OR 97219, USA. pamela@lclark.edu
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Zobel-Thropp
authors.forename: Alec E
authors.initials: AE
authors.lastname: Kerins
authors.forename: Greta J
authors.initials: GJ
authors.lastname: Binford
mesh_terms: D000818:Animals; D060829:Arthropod Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D001522:Behavior, Animal; D005247:Feeding Behavior; D006135:Gryllidae; D007103:Immobilization; D007306:Insecticides; D007928:Lethal Dose 50; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D013045:Species Specificity; D013109:Sphingomyelins / Q000378:metabolism; D013111:Spider Venoms / Q000201:enzymology* / Q000494:pharmacology; D013112:Spiders / Q000201:enzymology*
chemical_list: D060829:Arthropod Proteins; D007306:Insecticides; D011994:Recombinant Proteins; D013109:Sphingomyelins; D013111:Spider Venoms; D010727:Phosphoric Diester Hydrolases; C055160:sphingomyelin phosphodiesterase D