IS1

Description:

IS1 is a 768 bp transposable insertion sequence.
It contains two open reading frames, insA and insB, involved in transposase function.

Details:

IS1 can generate an 8 or 9 bp target site duplication, but some insertions have no apparent target site duplication.

The parental MG1655 strain (ATCC 47076; CGSC 6300) contains six instances of IS1 insertion. Prior to genome sequencing, MG1655(Seq) (ATCC 700926; CGSC 7740) acquired two new IS1 insertions: IS1H in the flhDC promoter region confers hypermotility and IS1I interrupts the crl gene (Barker, 2004; Freddolino, 2012).

IS1A, IS1E, IS1H and IS1I are iso-allelic, indicating that the two recent MG1655(Seq)-specific IS1 insertions originated from either IS1A or IS1E. IS1B, IS1C and IS1D are iso-allelic and have nine DNA substitutions relative to the IS1AEHI alleles, causing L81F polymorphism in InsA2-4 as well as T17P, S18P, L19F, S65R, and H128Y polymorphism in InsB2-4. IS1F' has accumulated 77 DNA substitutions relative to the IS1AEHI alleles; the insB6' codon for W98 is replaced by an in-frame stop codon and InsB6' has 16 amino acid differences relative to InsB1,5,8,9.


IS1 Left End Right End Ori Length Comments
IS1A 19796 20563 (-) 768
IS1I 257908 258675 (-) 768 IS1I insertion creates an 8 bp target site duplication TGAAGGTA and interrupts crl.
IS1B 279163 279930 (-) 768 IS1B interrupts afuB, deleting its N-terminus.
IS1C 290634 291401 (-) 768
IS1D 1049778 1050545 (+) 768 IS1D insertion creates a 9 bp target site duplication GACAATACG and silences the gfcABCDE-etp-etk operon.
IS1H 1978503 1979270 (-) 768 IS1H insertion creates an 8 bp target site duplication CATTTATG.
IS1E 3583428 3584195 (+) 768 IS1E insertion creates a 9 bp target site duplication GACATTAAA and interrupts yrhA.
IS1F' 4518472 4519239 (+) 768 IS1F' is an IS1 pseudo-element due to a nonsense mutation in insB6'.

IS1G is an insertion in K-12 strain W3110 that is not present in MG1655(Seq); the corresponding insertion point in MG1655(Seq) is at position 2406787.