Characterization of a Class II Defective Transposon Carrying Two Haloacetate Dehalogenase Genes from
            <i>Delftia acidovorans</i>
            Plasmid pUO1

Sota, Masahiro; Endo, Masahiro; Nitta, Keiji; Kawasaki, Haruhiko; Tsuda, Masashi

doi:10.1128/aem.68.5.2307-2315.2002

Cited by 34 publications

(37 citation statements)

References 49 publications

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“…TnHad2 has the 38-bp terminal IRs, IR1 and IR3, and the res site ( Fig. 1A and 2A), each of which shares extensive homology to the corresponding sequence of Tn21, and the supply in trans of the Tn21 transposition genes enables the complete transposition of TnHad2 (10). The sequence of IR2, which is highly homologous to IR1, is also located very close to the res site, although the 5Ј end of IR2 on pUO1 is occupied by the C residue ( Fig.…”

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confidence: 99%

“…A 67-kb self-transmissible and broad-host-range but not-well characterized plasmid, pUO1, from Delftia acidovorans strain B carries, in addition to the mer genes for resistance to mercury, two haloacetate dehalogenase genes (dehH1 and dehH2) on the two transposons, TnHad1 and TnHad2 (Fig. 1A) (10). TnHad1, with a size of 8.9 kb, is a class I transposon that carries dehH2 between two directly repeated copies of IS1071 (8), and dehH1 and TnHad1 are loaded on a 15.6-kb class II transposon, TnHad2, that lacks the tnpA and tnpR genes (Fig.…”

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confidence: 99%

“…However, the first 5Ј position of IR2 of mini-TnHad2 was occupied by the C residue, generating the 5Ј-CGGG end ( Fig. 2A) (10). We have previously replaced this C residue with the T residue, and this mutant version of mini-TnHad2 with an additional insert of a kanamycin resistance (Km r ) gene was cloned into a p15A-based Cm r vector, pSTV29 (TAKARA BIO), to obtain pMS015 ( Fig.…”

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confidence: 99%

“…TnHad1, with a size of 8.9 kb, is a class I transposon that carries dehH2 between two directly repeated copies of IS1071 (8), and dehH1 and TnHad1 are loaded on a 15.6-kb class II transposon, TnHad2, that lacks the tnpA and tnpR genes (Fig. 1A) (10). TnHad2 has the 38-bp terminal IRs, IR1 and IR3, and the res site ( Fig.…”

mentioning

confidence: 99%

“…We have previously replaced this C residue with the T residue, and this mutant version of mini-TnHad2 with an additional insert of a kanamycin resistance (Km r ) gene was cloned into a p15A-based Cm r vector, pSTV29 (TAKARA BIO), to obtain pMS015 ( Fig. 2B) (10). The mini-TnHad2 derivative on pMS015 has been found to still transpose efficiently in the presence of the Tn21 transposase, generating the transposed fragment having IR1 (5Ј-GGGG end) and the mutant IR2 (5Ј-TGGG end) at the extremities (10).…”

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Structure of Haloacetate-Catabolic IncP-1β Plasmid pUO1 and Genetic Mobility of Its Residing Haloacetate-Catabolic Transposon

2003

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The self-transmissible plasmid pUO1 from Delftia acidovorans strain B carries two haloacetate-catabolic transposons, TnHad1 and TnHad2, and the mer genes for resistance to mercury. The complete 67,066-bp sequence of pUO1 revealed that the mer genes were also carried by two Tn402/Tn5053-like transposons, Tn4671 and Tn4672, and that the pUO1 backbone regions shared 99% identity to those of the archetype IncP-1␤ plasmid R751. Comparison of pUO1 with three other IncP-1␤ plasmids illustrated the importance of transposon insertion in the diversity and evolution of this group of plasmids. Mutational analysis of the four outermost residues in the inverted repeats (IRs) of TnHad2, a Tn21-related transposon, revealed a crucial role of the second residue of its IRs in transposition.It has been demonstrated that bacterial genes for the degradation of various xenobiotic compounds are often loaded on transposable elements that are mainly classified into two major groups: class I and class II transposons (14). The class I transposon is a mobile element in which a short DNA segment is flanked by two copies of an insertion sequence (IS). The class II transposon usually carries transposase (TnpA), resolvase (TnpR), and a resolution (res) site between short terminal inverted repeats (IRs) and transposes by a two-step processcointegration and resolution (3, 9). Broad-host-range and selftransmissible plasmids are well known to contribute to the wide dissemination of these catabolic transposons (13). The successful conjugal transfer of these plasmids facilitates the spread of the catabolic transposons and at times promotes the evolution of novel catabolic pathways by genetic rearrangements (15). A 67-kb self-transmissible and broad-host-range but not-well characterized plasmid, pUO1, from Delftia acidovorans strain B carries, in addition to the mer genes for resistance to mercury, two haloacetate dehalogenase genes (dehH1 and dehH2) on the two transposons, TnHad1 and TnHad2 (Fig. 1A) (10). TnHad1, with a size of 8.9 kb, is a class I transposon that carries dehH2 between two directly repeated copies of IS1071 (8), and dehH1 and TnHad1 are loaded on a 15.6-kb class II transposon, TnHad2, that lacks the tnpA and tnpR genes (Fig. 1A) (10). TnHad2 has the 38-bp terminal IRs, IR1 and IR3, and the res site (Fig. 1A and 2A), each of which shares extensive homology to the corresponding sequence of Tn21, and the supply in trans of the Tn21 transposition genes enables the complete transposition of TnHad2 (10). The sequence of IR2, which is highly homologous to IR1, is also located very close to the res site, although the 5Ј end of IR2 on pUO1 is occupied by the C residue (Fig. 1A and 2A). In our previous study (10), we replaced this C residue with the T residue, and the mini-TnHad2 derivative flanked by this IR2 derivative (5Ј-TGGG end) and IR1 (5Ј-GGGG end) (Fig. 2B) was found to transpose at a high frequency in the presence of the Tn21 tnpA gene. This finding was unexpected, since (i) the outermost four G residues of the IRs are conserved in ...

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Structure of Haloacetate-Catabolic IncP-1β Plasmid pUO1 and Genetic Mobility of Its Residing Haloacetate-Catabolic Transposon

2003

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Horizontal Gene Transfer in Metal and Radionuclide Contaminated Soils

Sobecky¹,

Coombs

2009

Horizontal Gene Transfer

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The horizontal transfer of genes encoded on mobile genetic elements (MGEs) such as plasmids and phage and their associated hitchhiking elements (transposons, integrons, integrative and conjugative elements, and insertion sequences) rapidly accelerate genome diversification of microorganisms, thereby affecting their physiology, metabolism, pathogenicity,and ecological character. The analyses of completed prokaryotic genomes reveal that horizontal gene transfer (HGT) continues to be an important factor contributing to the innovation of microbial genomes. Indeed, microbial genomes are remarkably dynamic and a considerable amount of genetic information is inserted or deleted by HGT mechanisms. Thus, HGT and the vast pool of MGEs provide microbial communities with an unparalleled means by which to respond rapidly to changing environmental conditions and exploit new ecological niches. Metals and radionuclide contamination in soils, the subsurface, and aquifers poses a serious challenge to microbial growth and survival because these contaminants cannot be transformed or biodegraded into non-toxic forms as often occurs with organic xenobiotic contaminants. In this chapter we present cases in which HGT has been demonstrated to contribute to the dissemination of genes that provide adaptation to contaminant stress (i.e., toxic heavy metals and radionuclides). In addition, we present directions for future studies that could provide even greater insights into the contributions of HGT to adaptation for survival in mixed waste sites.

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