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IS 231A insertion specificity: consensus sequence and DNA bending at the target site
Author(s) -
Hallet Bernard,
Rezsöhazy René,
Mahilton Jacques,
Delcour Jean
Publication year - 1994
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1994.tb01273.x
Subject(s) - biology , insertion sequence , transposase , transposable element , dna , inverted repeat , tn10 , consensus sequence , genetics , repeated sequence , sequence (biology) , insertion , escherichia coli , microbiology and biotechnology , mutation , base sequence , gene , mutant , genome
Summary In its natural host, Bacillus thuringiensis , the insertion sequence IS 231 A is preferentially inserted into the terminal inverted repeats of the transposon Tn 4430. Using a novel transposition assay, we demonstrate that the Tn 4430 ends behave as insertion hot spots for IS 231 A in Escherichia coli. Sequence analysis reveals that IS 231 A insertion sites match the 5′‐GGG(N) 5 CCC‐3′consensus. However, this consensus is not the only determinant of IS 231 A insertion specificity. Although both Tn 4430 ends have identical sequences, one is strongly preferred to the other and the orientation of insertion into this end is not random. We demonstrate that this preference is determined by the flanking regions of the site. These regions display a conserved periodic organization of their sequence which, by conferring anisotropic flexibility, would induce the DNA to bend in a roughly ‘S’ ‐shaped structure centred on the target consensus. DNA conformation analysis by polyacrylamide gel electrophoresis indeed shows that the preferred target site of IS 231 A is flanked by DNA segments curved in opposite directions. We present a model in which DNA bendability and curvature would contribute to the positioning of IS 231 A transposase on the target DNA.