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Characterization of the Pseudomonas cepacia transposable elements IS401, IS406 and IS408
Abstract
This study describes the nucleotide sequence analyses of three transposable elements, IS401, IS406, and IS408, from Pseudomonas cepacia. These were among a number of insertion sequences identified in this bacterium on the basis of their abilities to promote genomic rearrangements and to recruit foreign genes by replicon fusion and insertional activation. Nucleotide sequence analyses of IS401 (1316 bp), IS406 (1368 bp), and IS408 (ca. 2.8 kb), revealed features characteristic of insertion sequences: terminal inverted repeats; target site duplications; and open reading frames (ORFs) encoding putative transposases. IS406 inserted into the lac promoter of Tn951 (Tnlac) on pGC91.14, leading to the duplication 8 bp of its $-$10 region. The hybrid promoter formed may be responsible for increased lac gene expression in P. cepacia. IS406 had 41-bp terminal inverted repeats with 11 mismatches. The left terminal inverted repeat of IS406 contained a 12-bp motif also present at the ends of Tn2501, a transposon located downstream of the lacY gene in Tn951. Searches of the EMBL and GenBank databases revealed similarities, at the amino acid level, between the putative transposases of IS406 and of elements from Staphylococcus aureus, Rhizobium meliloti, and Thiobacillus ferroxidans. IS408 from pTGL68 inserted into the lacZ gene of Tn951, 1895 nucleotides upstream of the Tn951 lacY gene, generating 8-bp target sequence duplications. IS408 on pTGL68 had 49-bp terminal inverted repeats with 9 mismatches. IS408 was also present on the 170-kb cryptic plasmid, pTGL1, harbored by our laboratory strain. The bulk of the nucleotide sequence data for IS408 was obtained from analysis of the 4.1-kb HindIII fragment of pTGL5, a derivative of pTGL1 carrying a copy of IS401 next to IS408. Analysis of this fragment provided the complete nucleotide sequence of IS401 and showed that the element inserted 91 bp away from IS408, duplicating 3 bp of pTGL1 DNA. IS401 had 26-bp terminal inverted repeats with 2 mismatches. Plasmid pTGL5 carried two other copies of IS401. Their terminal inverted repeat sequences were identical to those of the copy of IS401 next to IS408. IS401 was closely related to elements from Pseudomonas syringae subsp. savastanoi and Escherichia coli.
Subject Area
Microbiology|Molecular biology
Recommended Citation
Byrne, Armando M., "Characterization of the Pseudomonas cepacia transposable elements IS401, IS406 and IS408" (1992). Doctoral Dissertations Available from Proquest. AAI9219413.
https://scholarworks.umass.edu/dissertations/AAI9219413