Cloning and Characterization of Two Novel Crystal Protein Genes from a Bacillus thuringiensis serovar dakota Strain

Abstract

Two genes encoding the 32- and 40-kDa polypeptides of Bacillus thuringiensis strain 90-F-45-14 crystals were cloned, expressed in an acrystalliferous B. thuringiensis strain, and sequenced. The polypeptides had deduced molecular weights of 30,319 and 33,885, respectively. The amino acid sequence of the 32-kDa protein was 37.7% identical to the known sequence of a non-insecticidal parasporal protein in B. thuringiensis serovar thompsoni crystals. The sequence of the cloned 40-kDa protein was 37.0% and 22.3% identical to that of the existing Cry protein classes, Cry15Aa1 and Cry23Aa1, respectively. Thus, this protein constitutes a novel protein class, Cry33Aa1. The open reading frames of the two genes were located on the predominant plasmid of 17,629 bp (=11,752 MDa) in the same orientation, and they were separated by the sequence of 32 nucleotides. The two proteins are likely produced simultaneously from a single transcript to form spherical crystals.