title: Tightly bound binary toxin in the cell wall of Bacillus sphaericus.
abstract: We have shown that urea-extracted cell wall of entomopathogenic Bacillus sphaericus 2297 and some other strains is a potent larvicide against Culex pipiens mosquitoes, with 50% lethal concentrations comparable to that of the well-known B. sphaericus binary toxin, with which it acts synergistically. The wall toxicity develops in B. sphaericus 2297 cultures during the late logarithmic stage, earlier than the appearance of the binary toxin crystal. It disappears with sporulation when the binary toxin activity reaches its peak. Disruption of the gene for the 42-kDa protein (P42) of the binary toxin abolishes both cell wall toxicity and crystal formation. However, the cell wall of B. sphaericus 2297, lacking P42, kills C. pipiens larvae when mixed with Escherichia coli cells expressing P42. Thus, the cell wall toxicity in strongly toxic B. sphaericus strains must be attributed to the presence in the cell wall of tightly bound 51-kDa (P51) and P42 binary toxin proteins. The synergism between binary toxin crystals and urea-treated cell wall preparations reflects suboptimal distribution of binary toxin subunits in both compartments. Binary toxin crystal is slightly deficient in P51, while cell wall is lacking in P42.
authors.affiliation: Department of Biological Chemistry, A. Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Daniela
authors.initials: D
authors.lastname: Klein
authors.forename: Igor
authors.initials: I
authors.lastname: Uspensky
authors.forename: Sergei
authors.initials: S
authors.lastname: Braun
mesh_terms: D000818:Animals; D001407:Bacillus / Q000378:metabolism*; D001427:Bacterial Toxins / Q000378:metabolism* / Q000494:pharmacology; D002473:Cell Wall / Q000378:metabolism*; D009033:Culicidae / Q000187:drug effects; D004357:Drug Synergism; D004527:Egg Proteins / Q000378:metabolism; D004798:Enzymes / Q000378:metabolism; D015870:Gene Expression; D006358:Hot Temperature; D007814:Larva / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000378:metabolism; D011956:Receptors, Cell Surface; D014508:Urea / Q000737:chemistry; D000072216:Zona Pellucida Glycoproteins
chemical_list: D001427:Bacterial Toxins; D004527:Egg Proteins; D004798:Enzymes; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D000072216:Zona Pellucida Glycoproteins; C046134:binB protein, Bacillus sphaericus; D014508:Urea