A fusion promoter created by a new insertion sequence, IS1490, activates transcription of 2,4,5-trichlorophenoxyacetic acid catabolic genes in Burkholderia cepacia AC1100

Abstract

Transposition and transcriptional activation by insertion sequences in Burkholderia cepacia AC1100 were investigated. Two closely related new elements, IS1413 and IS1490, were identified and characterized. These elements are not highly related to other insertion sequences identified in AC1100 or other B. cepacia isolates. Based on their structures and the sequences of the inverted terminal repeats and the putative transposase protein, the insertion elements (IS elements) are similar to IST2 of Thiobacillus ferrooxidans and several related elements. All the IS elements that have been identified in this strain are found in multiple copies (10 to 40), and they have high-level promoter activity capable of stimulating transcription from a distance up to 500 bp from a target gene. Strain AC1100 was originally isolated after prolonged selection for the ability to utilize the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as a sole carbon source. Three IS elements are located near the first gene of the 2,4,5-T catabolic pathway, tftA. IS1490 inserted 110 bp upstream of tftA and created a fusion promoter responsible for constitutive transcription of the gene. Our results confirm the hypothesis that IS elements play a central role in transcription of 2,4,5-T genes and likely have stimulated rapid evolution of the metabolic pathway.

Characterization of the Variants, Flanking Genes, and Promoter Activity of the Leifsonia xyli subsp. cynodontis Insertion Sequence IS 1237

“…They cause insertion mutations and genome rearrangements and help mediate the spread of resistance and virulence determinants within and among species. In other cases, however, IS insertion also leads to activation or alteration of the expression of adjacent genes (3,4,6,17,18,19,30,36,38).…”

Identification and Characterization of Transposable Elements of Paracoccus pantotrophus

“…The transposition of these elements usually involves structural changes in DNA that lead to the formation of mutations: insertions, deletions, inversions, and translocations (of even large DNA fragments), which may result in varied phenotypic effects (19). Insertion of ISs can lead to gene disruption or activation of adjacent cryptic genes by formation of upstream promoters (29). ISs are therefore the most recombinogenic factor of bacterial genomes.…”

Multiple Mobile Promoter Regions for the Rare Carbapenem Resistance Gene of Bacteroides fragilis

“…These elements are capable of generating mutations and genome rearrangements as a result of translocation, of promoting gene acquisition, and of mobilizing DNA fragments via the formation of compound transposons (13,14). By various mechanisms, the presence or mobility of these elements may affect degradative pathways (9,10), bacterial pathogenicity or virulence (8,35), and resistance to antibiotics (15,17) and may condition gene expression. Genes may be silenced by insertional gene disruption and reactivated by precise excision (8,11,35).…”

“…Genes may be silenced by insertional gene disruption and reactivated by precise excision (8,11,35). Gene activation also may result from the provision of efficient promoters, carried either entirely by the element (10,17) or generated as hybrid structures between IS, upon insertion, and target sequences (5,9,12,15).…”