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Noninsecticidal Parasporal Proteins of a Bacillus thuringiensis Serovar shandongiensis Isolate Exhibit a Preferential Cytotoxicity against Human Leukemic T Cells

2000; Elsevier BV; Volume: 272; Issue: 1 Linguagem: Inglês

10.1006/bbrc.2000.2765

1090-2104

Dae-Weon Lee, Tetsuyuki Akao, Satoko Yamashita, Hideki Katayama, Minoru Maëda, Hiroyuki Saitoh, Eiichi Mizuki, Michio Ohba,

Entomopathogenic Microorganisms in Pest Control

A Bacillus thuringiensis isolate, 89-T-34-22, belonging to the serovar shandongiensis (H22) produced noninsecticidal and nonhemolytic proteins crystallizing into irregular-shaped parasporal inclusions. The proteins showed in vitro cytotoxicity to human cells, including cancer cells, only when activated by protease treatment. The human leukemic T (MOLT-4) cells were >100 times more susceptible than HeLa and normal T cells to the proteins of 89-T-34-22. The cytotoxicity was dose dependent and the median effective concentration for the MOLT-4 was 3.5 μg/ml. The cytopathy induced by the 89-T-34-22 proteins was characterized by remarkable condensation of the nucleus and cell-ballooning. Five major parasporal proteins of 89-T-34-22, with molecular masses in the range of 16–160 kDa, shared no similarity with the previously reported proteins in terms of the N-terminal sequence.