Parasporin-1, a novel cytotoxic protein to human cells from non-insecticidal parasporal inclusions of Bacillus thuringiensis.
Pro-parasporin-1 is a parasporal inclusion protein of the non-insecticidal Bacillus thuringiensis strain A1190. Cytotoxic fragments, named parasporin-1, were generated from pro-parasporin-1 by trypsin digestion. Parasporin-1 was purified by a combination of chromatography procedures based on the cytotoxic activity to HeLa cells. Two different fragments of 15-kDa and 56-kDa were detected in the purified parasporin-1 fraction. These fragments were tightly associated with each other and could not be separated by chromatography under conditions that preserve cytotoxic activity, indicating that the active form of parasporin-1 is a heterodimer of the 15- and 56-kDa fragments. Amino acid sequencing and MALDI-TOF mass spectrometric analysis revealed that parasporin-1 is generated from pro-parasporin-1 by trypsin digestion at Arg 93 and Arg 231. Of 12 human cell lines tested, parasporin-1 showed strong cytotoxicity to four cell lines derived from cancer tissues, but low to no cytotoxicity to the other cell lines. The time-courses of cytotoxicity indicated that the mode of action of parasporin-1 to sensitive cells differs from that shown for previously isolated cytotoxic proteins from Bacillus thuringiensis, Cyt proteins, and other bacterial pore-forming toxins. Thus, parasporin-1 is a novel cytotoxic protein to human cancer cells produced by B. thuringiensis, and may be useful as a tool to recognize and destroy specific cancer cells.
Katayama
Hideki
H
Biotechnology and Food Research Institute, Fukuoka Industrial Technology Center, Kurume, Fukuoka 839-0861, Japan.
Yokota
Haruo
H
Akao
Tetsuyuki
T
Nakamura
Osamu
O
Ohba
Michio
M
Mekada
Eisuke
E
Mizuki
Eiichi
E
D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D001427:Bacterial Toxins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D002460:Cell Line; D002522:Chlorocebus aethiops; D004731:Endotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D006801:Humans; D051379:Mice
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; C412914:parasporin