Abstract
Two novel crystal protein genes, designated as cry39A and 39orf2, were cloned from Bacillus thuringiensis (Bt) subsp. aizawai Bun1-14. When sequenced, these genes were found to contain open reading frames for proteins of 75 kDa and 63 kDa, respectively. The Cry39A protein, which is a typical Bt crystal protein, revealed five conserved blocks (block1 to block5). The 39Orf2 protein showed high homology to the carboxyl half of the 130 kDa Cry proteins such as Cry4A and had three conserved blocks (block6 to block8). The cry39A and 39orf2 genes were expressed in an acrystalliferous B. thuringiensis strain. Cry39A formed bipyramidal crystal inclusions only in the presence of 39Orf2 and was toxic to mosquito larvae as a wild type strain Bun1-14. No crystal inclusion was observed when 39Orf2 was truncated.
