Functional Analysis of Unique Class II Insertion Sequence IS 1071

Abstract

Various xenobiotic-degrading genes on many catabolic plasmids are often flanked by two copies of an insertion sequence, IS1071. This 3.2-kb IS element has long (110-bp) terminal inverted repeats (IRs) and a transposase gene that are phylogenetically related to those of the class II transposons. However, the transposition mechanism of IS1071 has remained unclear. Our study revealed that IS1071 was only able to transpose at high frequencies in two environmental ␤-proteobacterial strains, Comamonas testosteroni and Delftia acidovorans, and not in any of the bacteria examined which belong to the ␣-and ␥-proteobacteria. IS1071 was found to have the functional features of the class II transposons in that (i) the final product of the IS1071 transposition was a cointegrate of its donor and target DNA molecules connected by two directly repeated copies of IS1071, one at each junction; (ii) a 5-bp duplication of the target sequence was observed at the insertion site; and (iii) a tnpA mutation of IS1071 was efficiently complemented by supplying the wild-type tnpA gene in trans. Deletion analysis of the IS1071 IR sequences indicated that nearly the entire region of the IRs was required for its transposition, suggesting that the interaction between the transposase and IRs of IS1071 might be different from that of the other well-characterized class II transposons.

Genomic and Functional Analysis of the IncP-9 Naphthalene-Catabolic Plasmid NAH7 and Its Transposon Tn 4655 Suggests Catabolic Gene Spread by a Tyrosine Recombinase

“…These findings suggest that different site-specific recombination systems might have been incorporated into an ancestral class II transposon that lacked such a recombination system, leading to the structural diversification of class II transposons. This is compatible with the proposals that the present members of class II transposons might have evolved by the insertion of various site-specific resolution systems into an ancestral element carrying only a tnpA gene and IRs (21,45,63).…”

Novel organization of aromatic degradation pathway genes in a microbial community as revealed by metagenomic analysis

“…Metabolic compounds: (1) naphthalene; (2) cis-1,2-dihydro-1,2-dihydroxynaphtalene; (3) 1,2-dihydroxynaphthalene; (4) 2-hydroxychromene-2-carboxylate; (5) cis-o-hydroxybenzalpyruvate; (6) salicylaldehyde; (7) pyruvate; (8) salicylate; (9) gentitase; (10) maleylpyruvate; (11) fumarylpyruvate; (12) fumarate; (13) The aniline-catabolizing gene cluster on pTDN1 is flanked by IS1071 (Fukumori and Saint, 2001). IS1071 is preferentially located on broad host-range IncP-1b plasmids and can transpose in b-proteobacterial strains with high frequency (Sota et al, 2006b). Downstream of the degradation gene cluster on 9C3, two truncated IS1071 transposase genes (ORF9C3-3 and À14) flank a complete set of mercury-resistance genes, merRTPCADE (ORF9C3-4 to 10) (Figure 1).…”

Degradation of chloroaromatics by Pseudomonas putida GJ31: assembled route for chlorobenzene degradation encoded by clusters on plasmid pKW1 and the chromosome

“…2), the predicted encoded peptide being identical with the Nterminal portion of TnpA of IS1071 of Pseudomonas sp. strain H and Comamonas testosteroni strain BR60 (Providenti et al, 2006;Sota et al, 2006). At 159 bp downstream of the tnpA3 start codon, an inverted repeat of 38 nt (IR2 'left'), identical to that of transposon Tn5501 (28 % identical nucleotides to IS1 'left'), disrupts the tnpA3 gene.…”