title: A novel negative regulatory factor for nematicidal Cry protein gene expression in Bacillus thuringiensis.
abstract: A 3-kb HindIII fragment bearing the cry6Aa2 gene and the adjacent and intergenic regions was cloned from Bacillus thuringiensis strain YBT-1518. Two open reading frames (ORFs), namely, orf1 (termed cry6Aa2) and orf2 that were separated by an inverted-repeat sequence were identified. orf1 encoded a 54-kDa protein that exhibited high toxicity to the plant-parasitic nematode Meloidogyne hapla. The orf2 expression product was not detected by SDS-PAGE, but its mRNA was detected by RT-PCR. The orf2 coexpressed with orf1 at a high level in the absence of the inverted-repeat sequence, whereas, the expression level of orf1 was decreased. When orf2 was mutated, the level of orf1 expression was enhanced obviously. In conclusion, the inverted-repeat sequence disturbs orf2 expression, and the orf2 downregulates orf1 expression. This is an example of novel negative regulation in B. thuringiensis and a potential method for enhancing the expression level of cry genes.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University,Wuhan, Hubei, P.R. China.
authors.forename: Ziquan
authors.initials: Z
authors.lastname: Yu
authors.forename: Peisheng
authors.initials: P
authors.lastname: Bai
authors.forename: Peisheng
authors.initials: P
authors.lastname: Bai
authors.forename: Weixing
authors.initials: W
authors.lastname: Ye
authors.forename: Fengjuan
authors.initials: F
authors.lastname: Zhang
authors.forename: Lifang
authors.initials: L
authors.lastname: Ruan
authors.forename: Ziniu
authors.initials: Z
authors.lastname: Yu
authors.forename: Ming
authors.initials: M
authors.lastname: Sun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D004731:Endotoxins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006460:Hemolysin Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009876:Operon; D010957:Plasmids; D012091:Repetitive Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014431:Tylenchoidea / Q000382:microbiology
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis