title: Parasporin 1Ac2, a novel cytotoxic crystal protein isolated from Bacillus thuringiensis B0462 strain.
abstract: Two novel parasporin (PS) genes were cloned from Bacillus thuringiensis B0462 strain. One was 100 % identical even in nucleotide sequence level with that of parasporin-1Aa (PS1Aa1) from B. thuringiensis A1190 strain. The other (PS1Ac2) showed significant homology (99 % identity) to that of PS1Ac1 from B. thuringiensis 87-29 strain. The 15 kDa (S(113)-R(250)) and 60 kDa (I(251)-S(777)) fragments consisting of an active form of PS1Ac2 were expressed as His-tag fusion. Upon purification under denaturing condition and refolding, the recombinant polypeptides were applied to cancer cells to analyze their cytotoxicities. 3-(4,5-Dimethyl-2-thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide assay revealed that either of 15 or 60 kDa polypeptide exhibited no cytotoxicity to HeLa cells, but they became cytotoxic upon mixed together. Our results suggested that PS1Ac2 was responsible for the cytotoxicity of B. thuringiensis B0462 strain, and that the formation of hetero-dimer of 15 and 60 kDa polypeptide was required for their cytotoxicity.
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, Tsushima-Naka 3-1-1 Kita-ku, Okayama 700-8530, Japan.
authors.forename: Shouta
authors.initials: S
authors.lastname: Kuroda
authors.forename: Anowara
authors.initials: A
authors.lastname: Begum
authors.forename: Mizue
authors.initials: M
authors.lastname: Saga
authors.forename: Akina
authors.initials: A
authors.lastname: Hirao
authors.forename: Eiichi
authors.initials: E
authors.lastname: Mizuki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakai
authors.forename: Tohru
authors.initials: T
authors.lastname: Hayakawa
mesh_terms: D001413:Bacillus thuringiensis / Q000737:chemistry / Q000235:genetics*; D004731:Endotoxins / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000633:toxicity; D006367:HeLa Cells; D006801:Humans; D010802:Phylogeny; D011993:Recombinant Fusion Proteins / Q000633:toxicity
chemical_list: D004731:Endotoxins; D011993:Recombinant Fusion Proteins; C412914:parasporin