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Appl. Environ. Microbiol., 01 1996, 80-86, Vol 62, No. 1
B Lambert, L Buysse, C Decock, S Jansens, C Piens, B Saey, J Seurinck, K Van Audenhove, J Van Rie, A Van Vliet and M Peferoen
The full characterization of a novel insecticidal crystal protein, named
Cry9Ca1 according to the revised nomenclature for Cry proteins, from
Bacillus thuringiensis serovar tolworthi is reported. The crystal protein
has 1,157 amino acids and a molecular mass of 129.8 kDa. It has the typical
features of the Lepidoptera-active crystal proteins such as five conserved
sequence blocks. Also, it is truncated upon trypsin digestion to a toxic
fragment of 68.7 kDa by removal of 43 amino acids at the N terminus and the
complete C-terminal half after conserved sequence block 5. The 68.7-kDa
fragment is further degraded to a nontoxic 55-kDa fragment. The crystal
protein has a fairly broad spectrum of activity against lepidopteran
insects, including members of the families Pyralidae, Plutellidae,
Sphingidae, and Noctuidae. A 50% lethal concentration of less than 100
ng/cm2 of diet agar was found for diamondback moth, European corn borer,
cotton bollworm, and beet armyworm. It is the first insecticidal crystal
protein with activity against cutworms. No activity was observed against
some beetles, such as Colorado potato beetle. The protein recognizes a
receptor different from that recognized by Cry1Ab5 in Ostrinia nubilalis
and Plutella xylostella. In Spodoptera exigua and P. xylostella, it binds
to a receptor which is also recognized by Cry1Cax but with a lower
affinity. In these insects, Cry1Cax probably binds with a higher affinity
to an additional receptor which is not recognized by Cry9Ca1. Elimination
of a trypsin cleavage site which is responsible for the degradation to a
nontoxic fragment did result in protease resistance but not in increased
toxicity against O. nubilalis.
Copyright © 1996, American Society for Microbiology
A Bacillus thuringiensis insecticidal crystal protein with a high activity against members of the family Noctuidae
Plant Genetic Systems N.V., Ghent, Belgium.
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