An analysis of the genes encoding the 51.4- and 41.9-kDa toxins of Bacillus sphaericus 2297 by deletion mutagenesis: the construction of fusion proteins

Abstract

A series of deletion mutants have been constructed, in which varying numbers of amino acids have been deleted from both the N- and C-termini of both the 51.4- and 41.9-kDa toxins of Bacillus sphaericus. The results show that between 34-39 and 52-54 amino acids respectively at the N- and C-termini of the 51.4-kDa protein, are not essential for toxicity. In the case of the 41.9-kDa protein, the removal of only 7 amino acids from the C-terminus abolishes toxicity whilst at least 17 amino acids can be deleted from the N-terminus without loss of toxicity. A fusion protein with the 51.4-kDa derived sequence N-terminal to the 41.9-kDa sequence yielded a protein of Mr 87 kDa which was not toxic by itself. When supplemented with cells expressing only the 51.4-kDa protein, toxicity was restored. In contrast, another fusion protein, in which the gene order was reversed, was shown to be fully active in toxicity assays.

Binding of purified Bacillus sphaericus binary toxin and its deletion derivatives to Culex quinquefasciatus gut: elucidation of functional binding domains

“…Consistent with previous results (Broadwell et al, 1990a, b; Davidson et al, 1990;Oei et al, 1990), when P51 or P42 were fed alone to larvae they were not toxic, even at a concentration of 250 pg ml-l . A combination of the two proteins was toxic to larvae, confirming that the C. Oei, J .…”

The bacterium, Lysinibacillus sphaericus, as an insect pathogen

“…Consistent with the processing of the toxin, deletion experiments have shown that 17 amino acids can be removed from both the N-and C-terminus of BinA and that 34 residues can be removed from the N-terminus and 53 from the C-terminus of BinB, without abolishing toxicity (Broadwell et al, 1990b;Clark and Baumann, 1990;Oei et al, 1990).…”

Purification and characterization of mosquitocidal Bacillus sphaericus BinA protein

“…The Bin toxin is composed of two polypeptides namely, BinA (Mr, 41.9 kDa) and BinB (Mr,51.4 kDa). Together these proteins are highly toxic to larvae of Culex (Broadwell et al, 1990;Oei et al, 1990;Nicolas et al, 1993). Comparison of the genome sequence of the mosquitocidal bacterium B. sphaericus C3-41 with other Bacillus species reveals that the bin genes are present only in a subset of B. sphaericus strains and these show high levels of similarity among different serotypes and isolates (Hu et al, 2008).…”