Category:Transposons

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Transposons on EcoliWiki

General Information and E. coli Transposons

Transposons (Tn) are genetic material whose only genes are related to transposition and self-propogation. [1] Transposons are the most common source of mutation in many organisms.

Transposons carry genes that are not directly related to insertion functions.[2] It is this feature that separates them from IS elements, which only carry genes for insertion. Interestingly, some transposons are flanked by IS elements, including Tn9 with 2 direct repeats of IS1.[3]

Transposons are divided into 3 general classes [4]:

  1. Class I (compound/composite) - including Tn5, Tn7 and Tn10
  2. Class II (complex) - including Tn3
  3. Class III - bacteriophage Mu and related phages

Composite or Class I or Non-Replicative Transposons

The class I transposons are flanked by complete IS elements, which can potentially move independent of the rest of the transposon[5].

Composite Transposition, uses transposase enzymes to catalyze 3’ and 5’ ends of the donor DNA, allowing the transposon to go through strand transfer, inserting itself into the target DNA[5].This method is also known as the cut-and-paste method or conservative transposition. .

Complex or Class II or Replicative Transposons

In contrast, class II transposons do not have complete IS elements that can potentially transpose separately. They must move as a single entity[5]. These transposons, represented by the prototypic Tn3, encode 2 gene products that are involved in a two step transposition method[6].

Complex Transposition still nicks the 3’ end of the donor DNA, but instead of cleaving the 5’ end of the donor DNA it fuses with the target DNA through strand transfer. It then goes through replication, which forms a cointegrate DNA structure[7]. This structure can then integrate simple insertions into the target DNA through site specific recombination[8]. This method is also known as the copy-and-paste method.

Transposons in various bacteria

This list includes many transposons from various Gram negative and Gram positive bacteria and some accessions.

Bacterial Transposon List

E. coli Transposons

  • Tn3 - beta-lactamase for Ampicillin resistance
  • Tn5 - kanamycin resistance
  • Tn7 - depending on the antibiotic cassette, resistance to trimethoprim, streptothricin, spectinomycin, streptomycin [9]
  • Tn9 - chloramphenicol resistance
  • Tn10 - tetracycline resistance
  • Tn903
  • Tn1681
  • Tngamma delta

Naming conventions for Transposons in E. coli

Normally, the number associated with the transposon name is italicized. For example, Tn10. [5]

A registry for transposons has been established and is available at http://www.ucl.ac.uk/eastman/tn/ and more information on the naming is also available from Roberts et al (2008)[10].

What happened to Tn1, 2, 4, 6 and 8?!

Initially, transposons were identified according to the plasmid it was isolated from[11], not their sequence similarity or lack thereof. For example, Tn1 is now classified as a Tn3-like transposon[5]. A registry for transposable elements was established in the 1970s by the late Dr. Esther Lederberg and specific sets of numbers were given upon request to investigators[11]. This registry continued through the 1980s and Dr. Lederberg published 2 papers on the registry (Lederberg, 1981[12] & Lederberg, 1987 [13]). The second paper included a registry for the IS numbers as well[13]. A registry[10] is now maintained by the Eastman Dental Institute at UCL (University College London) and can be accessed at http://www.ucl.ac.uk/eastman/tn/.

As for Tn8, I don't know!! Bren 17:10, 13 July 2011 (UTC)

Table 1: Transposons identified early and source plasmid <protect>

Transposon Name Plasmid Reference(s) Notes

Tn1

RP4

PMID:4609125[14]

Tn2

RSF1030

PMID:1091625[15]

Tn3

R1

PMID:1093180[16]

Tn4

R1

PMID:1093180[16]

Tn5

JR67

PMID:1059152[17]

Tn6

JR72

PMID:1059152[17]

Tn7

R483

PMID:767328[18]

Tn9

pSM14

PMID:1061090[19]

Tn10

R100

PMID:1104574[20] & PMID:1102715[21]


edit table

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See also

External links

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References

See Help:References for how to manage references in EcoliWiki.

  1. ↑ Neidhardt, FC et al. (1996) Escherichia coli and Salmonella typhimurium: Cellular and Molecular Biology 2nd ed. (ASM Press, Washington, DC)
  2. ↑ Shapiro, James A. (1983) Mobile Genetic Elements (Academic Press Inc, San Diego, CA ). ISBN 0-12-638680-3
  3. ↑ Alton, NK & Vapnek, D () Nucleotide sequence analysis of the chloramphenicol resistance transposon Tn9. Nature 282 864-9 PubMed
  4. ↑ Reznikoff, WS (1993) The Tn5 transposon. Annu. Rev. Microbiol. 47 945-63 PubMed
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Edited by Berg, Douglas E. and Martha Howe (1989) Mobile DNA (ASM Press, Washington, D.C) ISBN 1-55581-005-5
  6. ↑ Heffron, F et al. (1979) DNA sequence analysis of the transposon Tn3: three genes and three sites involved in transposition of Tn3. Cell 18 1153-63 PubMed
  7. ↑ Léonard, C & Mahillon, J (1998) IS231A transposition: conservative versus replicative pathway. Res. Microbiol. 149 549-55 PubMed
  8. ↑ Weinert, TA et al. (1983) Insertion sequence duplication in transpositional recombination. Science 222 755-65 PubMed
  9. ↑ Edited by Craig, Nancy L., Robert Craigie, Martin Gellert and Alan M. Lambowitz (2002) Mobile DNA II (ASM Press, Washington, D.C.) ISBN 1-55581-209-0
  10. ↑ 10.0 10.1 Roberts, AP et al. (2008) Revised nomenclature for transposable genetic elements. Plasmid 60 167-73 PubMed
  11. ↑ 11.0 11.1 Campbell, A et al. (1979) Nomenclature of transposable elements in prokaryotes. Plasmid 2 466-73 PubMed
  12. ↑ Lederberg, EM (1981) Plasmid reference center registry of transposon (Tn) allocations through July 1981. Gene 16 59-61 PubMed
  13. ↑ 13.0 13.1 Lederberg, EM (1987) Plasmid Reference Center Registry of transposon(Tn) and insertion sequence (IS) allocations through December 1986. Gene 51 115-8 PubMed
  14. ↑ Hedges, RW & Jacob, AE (1974) Transposition of ampicillin resistance from RP4 to other replicons. Mol. Gen. Genet. 132 31-40 PubMed
  15. ↑ Heffron, F et al. (1975) Origin of the TEM-beta-lactamase gene found on plasmids. J. Bacteriol. 122 250-6 PubMed
  16. ↑ 16.0 16.1 Kopecko, DJ & Cohen, SN (1975) Site specific recA--independent recombination between bacterial plasmids: involvement of palindromes at the recombinational loci. Proc. Natl. Acad. Sci. U.S.A. 72 1373-7 PubMed
  17. ↑ 17.0 17.1 Berg, DE et al. (1975) Transposition of R factor genes to bacteriophage lambda. Proc. Natl. Acad. Sci. U.S.A. 72 3628-32 PubMed
  18. ↑ Barth, PT et al. (1976) Transposition of a deoxyribonucleic acid sequence encoding trimethoprim and streptomycin resistances from R483 to other replicons. J. Bacteriol. 125 800-10 PubMed
  19. ↑ Gottesman, MM & Rosner, JL (1975) Acquisition of a determinant for chloramphenicol resistance by coliphage lambda. Proc. Natl. Acad. Sci. U.S.A. 72 5041-5 PubMed
  20. ↑ Foster, TJ et al. (1975) Translocation of the tetracycline resistance determinant from R100-1 to the Escherichia coli K-12 chromosome. J. Bacteriol. 124 1153-8 PubMed
  21. ↑ Kleckner, N et al. (1975) Mutagenesis by insertion of a drug-resistance element carrying an inverted repetition. J. Mol. Biol. 97 561-75 PubMed

Pages in category "Transposons"

The following 8 pages are in this category, out of 8 total.

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