2003 Fiscal Year Final Research Report Summary
Identification and characterizatioon of mobile genetic elements carrying xenobiotics-degrading genes from soil bacteria
| Project/Area Number |
12558065
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
環境保全
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| Research Institution | Tohoku University |
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Principal Investigator |
TSUDA Masataka Tohoku University, Graduate School of Life Sciences, Professor, 大学院・生命科学研究科, 教授 (90172022)
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| Co-Investigator(Kenkyū-buntansha) |
MINAMISAWA Kiwamu Tohoku University, Graduate School of Life Sciences, Professor, 大学院・生命科学研究科, 教授 (70167667)
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| Project Period (FY) |
2000 – 2003
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| Keywords | Xenobiotics / Soil bacteria / Microbial biodegradation / DNA rearrangements / Mobile generic element / Plasmid / Transposon / Site-specific recombination |
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| Research Abstract |
ABSTRACT
Various xenobiotics-degrading activities of soil bacteria are often encoded by mobile genetic elements such as plasmids and transposons, and this property allows the rapid dissemination and dynamic properties of the degradation genes in the environmental bacterial strains. The aim of this study is the identification and entrapment of such mobile elements and their detailed characterization.
1.A broad-host-range plasmid, pUO1, carries two haloacetate dehalogenase genes, dehH1, and dehH2. The latter gene was located in an IS1071-composite transposon, TnHad1, and dehH1 and TnHad1 transposon were located in a Tn21-type transposon, TnHad2. The terminal nucleotide sequences essential for the TnHad2 transposition was further clarified.
2.Transposition of toluene transposon Tn4651 requires the site-specific resolution between the duplicated copies of Tn4651 on the same molecule. This reaction was mediated at a defined res site in the presence of TnpS, and TnpT greatly enhanced the resolu
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tion frequency. TnpS also showed the site-specific integration activity without the involvement of TnpT. The Tn465l-type resolution systems were widely distributed among various soil bacterial strains.
3.The toluene-degrading gene cluster on plasmid pWW53 was located on an 80-kb transposon, Tn4657. A 41-kb region of Tn4657 containing the pWW53-specified replication genes was flanked by two copies of the res sites in an inverted configuration. The Tn4657 TnpR-mediated site-specific inversion between the two res sites generated another toluene transposon, Tn4656.
4.A naphthalene transposon Tn4655 carried several remnant segments of different transposons, suggesting that the present structure of Tn4655 was formed by repeated insertion of several transposons and their subsequent rearrangements. The Tn4655 TnpR protein also had the site-specific integration activity.
5.A soil bacterial strain was constructed that carried a chromosomal copy of the Tn4655 derivative defective in one gene for the naphthalene degradation. Use of this strain as a recipient in the conjugation experiments with soil samples gave rise to the transconjugants able to degrade naphthalene. The transconjugants contained broad-host-range plasmids that carried the genes for the degradation of naphthalene. Less
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