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Functional Analysis of Unique Class II Insertion Sequence IS 1071

2006; American Society for Microbiology; Volume: 72; Issue: 1 Linguagem: Inglês

10.1128/aem.72.1.291-297.2006

1098-5336

Masahiro Sota, Hirokazu Yano, Yuji Nagata, Yoshiyuki Ohtsubo, Hiroyuki Genka, Hisashi Anbutsu, Haruhiko Kawasaki, Masataka Tsuda,

Glycosylation and Glycoproteins Research

ABSTRACT Various xenobiotic-degrading genes on many catabolic plasmids are often flanked by two copies of an insertion sequence, IS 1071 . 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 IS 1071 has remained unclear. Our study revealed that IS 1071 was only able to transpose at high frequencies in two environmental β-proteobacterial strains, Comamonas testosteroni and Delftia acidovorans , and not in any of the bacteria examined which belong to the α- and γ-proteobacteria. IS 1071 was found to have the functional features of the class II transposons in that (i) the final product of the IS 1071 transposition was a cointegrate of its donor and target DNA molecules connected by two directly repeated copies of IS 1071 , 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 IS 1071 was efficiently complemented by supplying the wild-type tnpA gene in trans . Deletion analysis of the IS 1071 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 IS 1071 might be different from that of the other well-characterized class II transposons.