title: Characterization of regulatory regions involved in the inducible expression of chiB in Bacillus thuringiensis.
abstract: Expression of the chiB gene from Bacillus thuringiensis Bti75 was defined as inducible by the use of transcriptional fusions with the bgaB reporter gene. The transcription start site of the chiB gene was identified as the C base located 132 base pairs upstream of the start codon. Analysis of 5' and 3' deletions of the chiB promoter region revealed that the sequence from position -192 to +36 with respect to the transcription start site was necessary for wild-type levels of inducible expression of the chiB gene. The minimal promoter region for the expression of chiB gene was identified as the sequence from position -100 to +12. Furthermore, a 16-bp sequence (designated dre) downstream of the minimal promoter region of chiB was shown to be required for chitin induction. To confirm the function of this 16-bp sequence, 25 base substitutions were introduced into the dre site. Most of the mutations resulted in constitutive expression, or the efficiency of induction decreased. All mutations identified the dre sequence as a critical site for the inducible expression of chiB. In addition, the dre site was shown to interact with a sequence-specific DNA binding factor of strain Bti75 cultured in the absence of the inducer.
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, People's Republic of China.
authors.forename: Chi-Chu
authors.initials: CC
authors.lastname: Xie
authors.forename: Jin
authors.initials: J
authors.lastname: Shi
authors.forename: Hai-Yun
authors.initials: HY
authors.lastname: Jia
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Luo
authors.forename: Jun
authors.initials: J
authors.lastname: Cai
authors.forename: Yue-Hua
authors.initials: YH
authors.lastname: Chen
mesh_terms: D001413:Bacillus thuringiensis / Q000201:enzymology / Q000235:genetics*; D001483:Base Sequence; D002688:Chitinases / Q000096:biosynthesis / Q000235:genetics*; D004790:Enzyme Induction; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D017384:Sequence Deletion; D024363:Transcription Initiation Site
chemical_list: D002688:Chitinases