CHARACTERIZATION OF A CRY2A GENE CLONED FROM AN ISOLATE OF BACILLUS-THURINGIENSIS SEROVAR SOTTO

A cry2A-type gene, designated as cry2(SKW), was cloned from Bacillus t huringiensis serovar sotto SKW01-10.2-06, and some unique features of the gene were revealed. The cry2(SKW) gene encoded a polypeptide of 63 5 residues with a predicted molecular mass of 71,137 Da. Cry2(KW) had 95.4% identity with Cry2Aa in amino acid sequence and was two residues longer than Cry2Aa. Two open reading frames (ORFs), designated as orf 1 and orf2, were present upstream of the cry2(SKW) and showed high hom ology with the corresponding ORFs in the cry2Aa operon. The Orf2 from SKW01-10.2-06 contained a region of repeated sequences. However, unlik e Cry2Aa, Cry2(SKW) formed the cuboidal crystalline inclusions when th e cry2(SKW) gene was expressed in an acrystalliferous B. thuringiensis strain in the absence of the upstream ORFs. Furthermore, Cry2(SKW) wa s less toxic to a lepidopteran species, Bombyx mori, than Cry2Aa in sp ite of high homology between the two proteins.