Defensive Function of Transposable Elements in Bacteria

It has been widely debated whether transposable elementshave a positive or a negative effect on their host cells. This study demonstrated that transposable elements, specifically insertion sequences(ISs), can adopt a defensive role in Escherichia coli. IS1 and IS10 in three different E. coli strains (S17, DH5a and Nissle 1917) rapidly disrupted the I-CeuI gene (encoding I-CeuI endonuclease) on the plasmid pLO11-ICeuI as early as the 1st generation, despite the gene-circuit being under tight control of an arabinosepromoter. Proteomics analysis showed that the protein abundance profile of E. coli DH5a with pLO11-ICeuI in 5th generation was nearly opposite to that of control strain (E. coli with pLO11, no I-CeuI). The DNA damage caused by the leaky expression of I-CeuI was enough to trigger a SOS responseand alter lipid synthesis, ribosomal activity, RNA/DNA metabolism, central dogma and cell cycle processes in E. coli DH5a. After the ISs disrupted the expression of I-CeuI, cells fully recovered by the 3...