|Gene:||insAB-4||Accession Number: G0-10536 (EcoCyc)|
IS1 is the smallest insertion sequence in E. coli. It codes for three proteins, InsA, InsB and InsAB'.
InsAB' is the transposase for IS1 [Escoubas94]. Its translation depends on a -1 frameshift within the 3' end region of insA which allows translational readthrough into insB [Sekine89]. In the absence of this frameshift, the IS1 transcriptional repressor protein InsA is produced instead [Sekine89, Escoubas94, Matsutani97].
InsAB' acts preferentially near the IS1 sequence, thus promoting stable existence of the IS1 element within the genome [Matsutani97]. Its transposition function requires the H-NS DNA-binding transcriptional dual regulator [Shiga01].
The structural basis of InsAB' function has been examined [Ohta04, TonHoang04].
Note that although this page mentions "Exons/Introns" and "Spliced Nucleotide Sequence", it actually describes ribosomal frameshifting.
|Map Position: [1,049,056 -> 1,049,753] (22.61 centisomes)||Length: 698 bp / 232 aa|
Molecular Weight of Polypeptide: 26.517 kD (from nucleotide sequence)
|Biological Process:||GO:0006313 - transposition, DNA-mediated [Ohta04]|
|Molecular Function:||GO:0004803 - transposase activity [Ohta04]|
|MultiFun Terms:||extrachromosomal → transposon related|
Ingrid Keseler on Wed Mar 7, 2012:
Gene end position corrected to be the same as that of insB-4.
Ohta04: Ohta S, Yoshimura E, Ohtsubo E (2004). "Involvement of two domains with helix-turn-helix and zinc finger motifs in the binding of IS1 transposase to terminal inverted repeats." Mol Microbiol 53(1);193-202. PMID: 15225314
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