title: Contribution of S-layer proteins to the mosquitocidal activity of Lysinibacillus sphaericus.
abstract: Lysinibacillus sphaericus strains belonging the antigenic group H5a5b produce spores with larvicidal activity against larvae of Culex mosquitoes. C7, a new isolated strain, which presents similar biochemical characteristics and Bin toxins in their spores as the reference strain 2362, was, however, more active against larvae of Culex mosquitoes. The contribution of the surface layer protein (S-layer) to this behaviour was envisaged since this envelope protein has been implicated in the pathogenicity of several bacilli, and we had previously reported its association to spores. Microscopic observation by immunofluorescence detection with anti S-layer antibody in the spores confirms their attachment. S-layers and BinA and BinB toxins formed high molecular weight multimers in spores as shown by SDS-PAGE and western blot detection. Purified S-layer from both L. sphaericus C7 and 2362 strain cultures was by itself toxic against Culex sp larvae, however, that from C7 strain was also toxic against Aedes aegypti. Synergistic effect between purified S-layer and spore-crystal preparations was observed against Culex sp. and Aedes aegypti larvae. This effect was more evident with the C7 strain. In silico analyses of the S-layer sequence suggest the presence of chitin-binding and hemolytic domains. Both biochemical characteristics were detected for both S-layers strains that must justify their contribution to pathogenicity.
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.
authors.forename: Mariana Claudia
authors.initials: MC
authors.lastname: Allievi
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.
authors.forename: María Mercedes
authors.initials: MM
authors.lastname: Palomino
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.
authors.forename: Mariano
authors.initials: M
authors.lastname: Prado Acosta
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Lanati
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.
authors.forename: Sandra Mónica
authors.initials: SM
authors.lastname: Ruzal
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.
authors.forename: Carmen
authors.initials: C
authors.lastname: Sánchez-Rivas
mesh_terms: D000330:Aedes / Q000187:drug effects*; D000595:Amino Acid Sequence; D000818:Animals; D001406:Bacillaceae / Q000737:chemistry*; D002686:Chitin / Q000378:metabolism; D003465:Culex / Q000187:drug effects*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity*; D008969:Molecular Sequence Data; D011485:Protein Binding; D055503:Protein Multimerization; D013171:Spores, Bacterial / Q000737:chemistry
chemical_list: D008562:Membrane Glycoproteins; C055764:S-layer proteins; D002686:Chitin