@article{mbs:/content/journal/micro/10.1099/13500872-142-7-1825, author = "Gerischer, Ulrike and D'Argenio, David A. and Ornston, L. Nicholas", title = "IS 1236, a newly discovered member of the IS3 family, exhibits varied patterns of insertion into the Acinetobacter calcoaceticus chromosome", journal= "Microbiology", year = "1996", volume = "142", number = "7", pages = "1825-1831", doi = "https://doi.org/10.1099/13500872-142-7-1825", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-142-7-1825", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "Acinetobacter calcoaceticus", keywords = "mutation", keywords = "chromosome", keywords = "insertion sequence", keywords = "genetic targets", abstract = "Analysis of spontaneous mutations in Acinetobacter calcoaceticus revealed a 1237 bp insertion sequence named IS 1236 and possessing a nucleotide sequence resembling those of members of the IS3 family. The chromosome of A. calcoaceticus strain ADP1 contains seven copies of IS 1236 which appears to insert preferentially into pobR, the transcriptional activator of the structural gene for p-hydroxybenzoate hydroxylase. IS 1236 creates tandem 3 bp DNA duplications flanking the sites of its insertion in pobR. Different duplication patterns are found following insertion of IS 1236 into pcaH, a structural gene for protocatechuate 3,4-dioxygenase. Therefore the insertion properties of IS 1236 appear to be influenced by its DNA target. Amino acid sequences associated with the apparent transposase function have been conserved in ORFB of IS 1236 whereas the presumed DNA-binding helix-turn-helix region of IS 1236 ORFA exhibits substantial amino acid sequence divergence from its IS3 counterparts. IS 1236 ORFA and ORFB coding sequences overlap considerably, and sequence evidence indicates mechanisms for ORFB expression in IS 1236 may resemble those employed by other members of the IS3 family. Portions of the IS 1236 terminal repeats exhibit substantial sequence divergence from other members of the IS3 family, but evolution appears to have conserved a mechanism preventing expression of the insertion sequence genes as a consequence of transcriptional readthrough.", }