ISZm1068: an IS5-like insertion element from Zymomonas mobilis

A new insertion sequence, designated ISZm1068, was isolated from Zymomonas mobilis strain CP4. This element consists of 1,068 bp and contains one majo r ORF which shows similarities both at the nucleotide and at the amino acid sequence level with the corresponding ORFs encoding the transposases of ma ny IS5 family elements, in particular the IS1031 group. Moreover, the Z. mo bilis ORF shares the conserved N2, N3 and C1 signature motifs of the IS4 an d IS5 families. Six out of seven Z. mobilis wild-type strains were shown by hybridisation to contain a single copy of the ISZm1068 element. Nucleotide sequences of the insertion elements from these strains exhibited extremely high levels of identity, varying from 94.25 to 99.25%. ISZm1068 was shown to be active in Escherichia coli cells and led to plasmid replicon fusions within the host cell. Sequence analysis of rare cointegration and resolutio n derivatives suggests that ISZm1068 has putative imperfect inverted repeat s at its extremities of 18 bp (IR-right) and 14 bp (IR-left), and that a 3- bp (5'-TCA-3') target sequence is duplicated upon insertion.