title: Insecticidal toxin complex proteins from Xenorhabdus nematophilus: structure and pore formation.
abstract: Toxin complexes from Xenorhabdus and Photorhabdus spp. bacteria represent novel insecticidal proteins. We purified a native toxin complex (toxin complex 1) from Xenorhabdus nematophilus. The toxin complex is composed of three different proteins, XptA2, XptB1, and XptC1, representing products from class A, B, and C toxin complex genes, respectively. We showed that recombinant XptA2 and co-produced recombinant XptB1 and XptC1 bind together with a 4:1:1 stoichiometry. XptA2 forms a tetramer of ∼1,120 kDa that bound to solubilized insect brush border membranes and induced pore formation in black lipid membranes. Co-expressed XptB1 and XptC1 form a tight 1:1 binary complex where XptC1 is C-terminally truncated, resulting in a 77-kDa protein. The ∼30-kDa C-terminally cleaved portion of XptC1 apparently only loosely associates with this binary complex. XptA2 had only modest oral toxicity against lepidopteran insects but as a complex with co-produced XptB1 and XptC1 had high levels of insecticidal activity. Addition of co-expressed class B (TcdB2) and class C (TccC3) proteins from Photorhabdus luminescens to the Xenorhabdus XptA2 protein resulted in formation of a hybrid toxin complex protein with the same 4:1:1 stoichiometry as the native Xenorhabdus toxin complex 1. This hybrid toxin complex, like the native toxin complex, was highly active against insects.
authors.affiliation: Department of Biochemistry and Molecular Biology, Dow AgroSciences, Indianapolis, Indiana 46268, USA. jjsheets@dow.com
authors.forename: Joel J
authors.initials: JJ
authors.lastname: Sheets
authors.forename: Tim D
authors.initials: TD
authors.lastname: Hey
authors.forename: Kristin J
authors.initials: KJ
authors.lastname: Fencil
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Burton
authors.forename: Weiting
authors.initials: W
authors.lastname: Ni
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Lang
authors.forename: Roland
authors.initials: R
authors.lastname: Benz
authors.forename: Klaus
authors.initials: K
authors.lastname: Aktories
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D007306:Insecticides / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D007915:Lepidoptera; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D020593:Xenorhabdus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D007306:Insecticides; D046912:Multiprotein Complexes