Parasporin-2Ab, a newly isolated cytotoxic crystal protein from Bacillus thuringiensis

Curr Microbiol. 2007 Oct;55(4):278-83. doi: 10.1007/s00284-006-0351-8. Epub 2007 Aug 13.


A novel crystal protein that exhibited potent cytotoxicity against human leukemic T-cells was cloned from the Bacillus thuringiensis TK-E6 strain. The protein, designated as parasporin-2Ab (PS2Ab), was a polypeptide of 304 amino acid residues with a predicted molecular weight of 33,017. The deduced amino acid sequence of PS2Ab showed significant homology (84% identitiy) to parasporin-2Aa (PS2Aa) from the B. thuringiensis A1547 strain. Upon processing of PS2Ab with proteinase K, the active form of 29 kDa was produced. The activated PS2Ab showed potent cytotoxicity against MOLT-4 and Jurkat cells and the EC(50) values were estimated as 0.545 and 0.745 ng/mL, respectively. The cytotoxicity of PS2Ab was significantly higher than that of PS2Aa reported elsewhere. Although both cytotoxins were structurally related, it was thought that the minor differences found were responsible for the different cytotoxicities of PS2Ab and PS2Aa.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / isolation & purification
  • Antineoplastic Agents / toxicity*
  • Bacillus thuringiensis*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / isolation & purification
  • Bacterial Proteins / toxicity*
  • Bacterial Toxins / chemistry
  • Bacterial Toxins / genetics
  • Bacterial Toxins / toxicity*
  • Base Sequence
  • Endotoxins / genetics
  • Endotoxins / isolation & purification
  • Endotoxins / toxicity*
  • Humans
  • Jurkat Cells
  • Molecular Sequence Data
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / toxicity
  • Sequence Analysis, DNA
  • Tumor Cells, Cultured


  • Antineoplastic Agents
  • Bacterial Proteins
  • Bacterial Toxins
  • Endotoxins
  • Recombinant Proteins
  • parasporin
  • parasporin-2Ab protein, Bacillus thuringiensis