Mosquitocidal toxin

Priest, F. G. Ebdrup, L. Zahner, V. Carter, P. E. Distribution and characterization of mosquitocidal toxin genes in some strains of Bacillus sphaericus. Appl. Environ. Microbiol. 1997,63,1195-1198. 

So far, only two catalytic residues have been identified in SI Glu-129 (Antoine et ai, 1993) and His-35 (Antoine and Locht, 1994). The first residue is conserved in all known ADP-ribosylating toxins, whereas His-35 is only conserved in cholera toxin and a recently identified mosquitocidal toxin produced by Bacillus sphaericus. This residue is not present in diphtheria toxin and exotoxin A (Fig. 1). The absence of this catalytic residue in the latter two toxins may explain their inefficiency in carrying out the NAD -glycohydrolysis reaction, compared to PT and cholera toxin. The acceptor substrate of diphtheria toxin and exotoxin A is diphthamide, a modified histidine residue in EF2. Perhaps this residue may take on some of the functions of the catalytic His residue in the other toxins. 

Among these different biopesticides, bacterial biopesticides are the most intensively studied and widely used. Several insect pathogenic bacteria are known to produce proteins toxic to certain insects. Bacillus thurin ensis (Bt) is the most well-known bacterium for its potent insecticidal proteins. These proteins are highly specific to certain orders of insects. Insects sensitive to Bt include those of Coleoptera, Diptera, and Lepidoptera. Bacillus sphaericus and Clostridium bifermentans are known for their mosquitocidal proteins. Paenibadllus popilliae produces a scarab active toxin structurally similar to common insecticidal proteins... 

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