General Information/ IS derivatives of Tn3 family transposons
Another source of ambiguity for classification purposes occurs in the Tn3 family (see section “Tn families” and "Tn3 family") (Fig.10.1 and 10.2) . Tn3 family members are quite variable. They include a number of diverse passenger genes that can represent entire operons, notably mercury resistance, or individual genes involved in antibiotic resistance, breakdown of halogenated aromatics, or virulence [e.g. ]. They often carry integron recombination platforms, enabling them to incorporate additional resistance genes by recruiting integron cassettes . Members are quite characteristic: they have long relatively well conserved IR and a particularly long Tpase (950 to 1025 aa). They also encode a site-specific recombination (“resolution”) system necessary for completion of their transposition (Grindley 2002 - Chapter 14 from Mobile DNA II book). There are a number of different resolution systems associated with different members of this family (Fig.10.2) IS1071, (Fig.10.1) composed of Tn3-like IR and Tpase gene but lacking both the site-specific recombination system and passenger genes was identified many years ago. This clearly accords with the definition of an IS. Several other examples have now been identified (e.g. ISVsa19, ISShfr9, ISBusp1).
- Nicolas E, Lambin M, Dandoy D, Galloy C, Nguyen N, Oger CA, Hallet B . The Tn3-family of Replicative Transposons. - Microbiol Spectr: 2015 Aug, 3(4); [PubMed:26350313] [DOI]
- Liebert CA, Hall RM, Summers AO . Transposon Tn21, flagship of the floating genome. - Microbiol Mol Biol Rev: 1999 Sep, 63(3);507-22 [PubMed:10477306]
- Mazel D . Integrons: agents of bacterial evolution. - Nat Rev Microbiol: 2006 Aug, 4(8);608-20 [PubMed:16845431] [DOI]
- Nakatsu C, Ng J, Singh R, Straus N, Wyndham C . Chlorobenzoate catabolic transposon Tn5271 is a composite class I element with flanking class II insertion sequences. - Proc Natl Acad Sci U S A: 1991 Oct 1, 88(19);8312-6 [PubMed:1656436] [DOI]
- Wyndham RC, Nakatsu C, Peel M, Cashore A, Ng J, Szilagyi F . Distribution of the catabolic transposon Tn5271 in a groundwater bioremediation system. - Appl Environ Microbiol: 1994 Jan, 60(1);86-93 [PubMed:8117095]
- Lima-Mendez G, Oliveira Alvarenga D, Ross K, Hallet B, Van Melderen L, Varani AM, Chandler M . Toxin-Antitoxin Gene Pairs Found in Tn<i>3</i> Family Transposons Appear To Be an Integral Part of the Transposition Module. - mBio: 2020 Mar 31, 11(2); [PubMed:32234815] [DOI]