A new family of insecticidal crystal proteins was discovered by screening
sporulated Bacillus thuringiensis (B.t.) cultures for oral activity against
western corn rootworm larvae (WCR). B.t. isolates PS80JJ1, PS149B1, and
PS167H2 have WCR insecticidal activity attributable to parasporal inclusion
bodies containing proteins with molecular masses of ca.14 and 44 kDa. The
genes encoding these polypeptides reside in apparent operons with the 14 kDa
open reading frame (ORF) preceding the 44 kDa ORF. Mutagenesis of either
gene of the apparent operon dramatically reduced insecticidal activity of
the corresponding recombinant B.t. strain. Bioassays using separately
expressed, biochemically-purified 14 kDa and 44 kDa polypeptides also
demonstrated the requirement of both proteins in WCR mortality. Sequence
comparisons with other known B.t. insecticidal proteins failed to reveal
homology with Cry, Cyt or Vip proteins. However, evidence does exist for
evolutionary relatedness between the 44 kDa polypeptide and the 41.9 and
51.4 kDa binary dipteran insecticidal proteins from Bacillus sphaericus.
Species 1: Coleoptera Chrysomelidae Diabrotica virgifera (western corn rootworm)
Keywords: insecticidal proteins, mutagenesis
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA