Transposon Tn3

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Tn3 is a complex transposable element [1][2] that often carries ampicillin resistance [2].

Gene List for E. coli Transposon Tn3

Organization

This image was generated from a modified GenBank file from NCBI available only from EcoliWiki, referred to as BM_V00613.1. <gbrowseImage> name=BM_V00613.1:1..4957 source=Transposon_Tn3 width=800 type=Genes </gbrowseImage>

General Information about the Tn3-like Transposon Family

Transposons of the Tn3 family often carry the bla gene, which codes for beta-lactamase for Ampicillin resistance, but may also carry other antibacterial drug resistances or metal metabolism genes[3][4]. They encode a transposase, encoded by the tnpA gene, and a resolvase protein, encoded by tnpR[5].

Tn1 and Tn3 are nearly identical[6].

The Tn3-like family includes (this is not a comprehensive list):

  1. Tn1
  2. Tn2
  3. Tn3
  4. Tn21
  5. gamma delta (Tn1000)
  6. Tn501
  7. Tn551
  8. Tn801
  9. Tn917
  10. Tn1721
  11. Tn1722
  12. Tn2301

For a more complete list of bacterial transposons, including some accession, click here.

Complex or Class II Transposons

Most transposons in the Tn3 family do not excise themselves from the original position in the genome during replication[7]. The transposon is not replicated by the cut-and-paste method. Instead, the transposon forms a cointegrate (with the activity of the transposase and other host proteins) that is resolved by the resolvase protein[8]. This is the same method of replication used by bacteriophage Mu[7][9].

General Information about E. coli Transposon Tn3

As the prototypic Tn3 family representative, Tn3 transposes via the two step process of cointegrate formation and subsequent resolution. Tn3 encodes for three proteins:

  1. Transposose (tnpA gene product) - GO:0004803 Transposase Activity
  2. Resolvase (tnpR gene product) -
  3. Beta-lactamase (bla gene product) - GO:0008800 beta-lactamase activity

Sequence accessions

External Links

See also

References

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  1. ↑ Kretschmer, PJ & Cohen, SN (1977) Selected translocation of plasmid genes: frequency and regional specificity of translocation of the Tn3 element. J. Bacteriol. 130 888-99 PubMed
  2. ↑ 2.0 2.1 Heffron, F et al. (1977) Deletions affecting the transposition of an antibiotic resistance gene. Proc. Natl. Acad. Sci. U.S.A. 74 702-6 PubMed
  3. ↑ 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
  4. ↑ Mindlin, S et al. (2001) Mercury resistance transposons of gram-negative environmental bacteria and their classification. Res. Microbiol. 152 811-22 PubMed
  5. ↑ Gill, RE et al. () Identification of the protein encoded by the transposable element Tn3 which is required for its transposition. Nature 282 797-801 PubMed
  6. ↑ Chen, ST & Clowes, RC (1987) Variations between the nucleotide sequences of Tn1, Tn2, and Tn3 and expression of beta-lactamase in Pseudomonas aeruginosa and Escherichia coli. J. Bacteriol. 169 913-6 PubMed
  7. ↑ 7.0 7.1 Gill, R et al. (1978) Analysis of sequences transposed by complementation of two classes of transposition-deficient mutants of Tn3. J. Bacteriol. 136 742-56 PubMed
  8. ↑ McCormick, M et al. (1981) Plasmid cointegrates and their resolution mediated by transposon Tn3 mutants. Gene 15 103-18 PubMed
  9. ↑ Shapiro, JA (1979) Molecular model for the transposition and replication of bacteriophage Mu and other transposable elements. Proc. Natl. Acad. Sci. U.S.A. 76 1933-7 PubMed
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