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Volume 12, Issue 4

The novel pseudo-compound transposon Tn carries aminoglycoside resistance genes in Open Access

Abstract

is a member of the human gut microbiota and a pathogen responsible for mild and severe infections. Here, genome analysis of strains isolated from different body sites revealed the presence of a novel family of IS-flanked pseudo-compound transposons carrying aminoglycoside resistance genes and other resistance determinants. The representative element, named Tn, is 25,380 bp long, contains 27 ORFs and shows a mosaic structure containing (i) the macrolide–lincosamide–streptogramin resistance gene (B), (ii) the aminoglycoside–streptothricin resistance gene cluster , (iii) the gentamicin resistance determinant ″) and (iv) a toxin–antitoxin cassette. Tn family members contain deletions and/or insertions including three DNA segments, two of which carry antimicrobial resistance genes. All elements integrate downstream of a conserved 8-bp target site within the chromosomal gene, located between and and encoding a 2-dehydropantoate 2-reductase. Genome-wide analysis of 646 complete genomes showed disruption in 12.7% of isolates due to the presence of Tn family members (10.7%) or (2%), while an intact gene was found in the other genomes. Element integration produced either target-site duplication or DNA deletions, with or without the target site. PCR and sequencing analysis showed that Tn and Tn-like elements excise from the chromosome and produce circular translocatable units at frequencies of 1.24±0.03 to 22.4±17.7 copies per 10 chromosomes. In conclusion, we describe the novel Tn family of IS-flanked pseudo-compound transposons in , which carry multiple antimicrobial resistance genes, integrate at a specific chromosomal site within and are capable of excision to form circular translocatable units.

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Keyword(s): antimicrobial resistance genes , complete genome , Enterococcus faecalis , mobilome and pseudo-compound transposon
Funding
This study was supported by the:
  • Ministero dell'Università e della Ricerca (Award 2022ZJE2FH)
    • Principal Award Recipient: FrancescoIannelli
  • Ministero dell'Università e della Ricerca (Award P2022YFSCM)
    • Principal Award Recipient: FrancescoIannelli
  • Ministero dell'Università e della Ricerca (Award PE00000007)
    • Principal Award Recipient: FrancescoIannelli
© 2026 The Authors
  • This is an open-access article distributed under the terms of the Creative Commons Attribution License.
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2026-04-07
2026-04-18

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The novel pseudo-compound transposon Tn7086 carries aminoglycoside resistance genes in Enterococcus faecalis
M Gen 12, 001680 (2026); https://doi.org/10.1099/mgen.0.001680
/content/journal/mgen/10.1099/mgen.0.001680
/content/journal/mgen/10.1099/mgen.0.001680
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