Open AccessStructural and genetic organization of IS232, a new insertion sequence of Bacillus thuringiensis
Author(s) -
Ghislaine Menou,
Jacques Mahillon,
MargueriteM. Lecadet,
Didier Lereclus
Publication year - 1990
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.172.12.6689-6696.1990
Subject(s) - biology , inverted repeat , insertion sequence , genetics , bacillus thuringiensis , open reading frame , direct repeat , start codon , dna , nucleic acid sequence , escherichia coli , repeated sequence , gene , stop codon , transposable element , microbiology and biotechnology , peptide sequence , base sequence , bacteria , genome
In the Bacillus thuringiensis strains toxic for the lepidopteran larvae, the delta-endotoxin genes cryIA are frequently found within a composite transposonlike structure flanked by two inverted repeat sequences. We report that these elements are true insertion sequences and designate them IS232. IS232 is a 2,184-bp element and is delimited by two imperfect inverted repeats (28 of 37 bp are identical). Two adjacent open reading frames, overlapping for three codons, span almost the entire sequence of IS232. The potential encoded polypeptides of 50 and 30-kDa are homologous to the IstA and IstB proteins of the gram-negative insertion sequence IS21. The N-terminal part of the 50-kDa polypeptide contains a helix-turn-helix DNA-binding motif. The junctions at the insertion sites of three IS232 elements were analyzed. Each case was different, with 0, 4, or 6 bp of the target DNA being duplicated. Transposition of IS232 in Escherichia coli was demonstrated by using a genetic marker inserted upstream of the two open reading frames.