Representative IMEs

IMEs 1, 2 are defined as mobile genetic elements that encode their own excision and integration regardless of their mechanism and/or specificity of integration, and that do not encode the T4SS machinery and the coupling protein but are able to hijack or subvert the mating apparatus of related or unrelated conjugative elements (such as an IncA or IncC plasmid, or an ICE), regardless of mechanism. IMEs are autonomous in integration but nonautonomous in conjugation, and can be divided into two major subcategories: relaxosome-encoding and relaxosome-missing. Relaxosome-encoding IMEs have attL, int, rlx/mob, nic/oriT, and attR; the relaxase targets an oriT site and the resulting relaxosome is recruited to the T4SS together with a coupling protein encoded by a co-resident conjugative element. Relaxosome-missing IMEs have attL, int, nic/oriT, and attR, but contain no conjugal transfer genes; a co-resident conjugative element recognizes the nic/oriT site of the IME, sufficiently making its intercellular transfer and subsequent transposition.

Table 1|List of representative relaxosome-encoding IMEs

CategorySub-categoryDesignationAccession numberSynonymResistance genesDRFASTA sequenceGene listGBK-annotationSQN-annotationManual annotationGene organization
Relaxosome-encoding IME Tn4451 U15027 blaCARB-2, tetA(G), and floR GA
Relaxosome-encoding IME Tn4555 U75371 sul2
Relaxosome-encoding IME Tn6523 AF261825 SGI1 None
Relaxosome-encoding IME Tn6591 AE014073 GIsul2 cfxA
Relaxosome-encoding IME Tn6966 CP064830 tetA(B), sul1, qacED1, aadA16, dfrA27, arr-3, catB3, blaOXA-1, aacA4cr, floR, sul2, aph(4)-Ia, aacC4, aphA1, aadA2, dfrA12, and dfrA12

Table 2|List of representative relaxosome-missing IMEs

CategorySub-categoryDesignationAccession numberSynonymResistance genesDRFASTA sequenceGene listGBK-annotationSQN-annotationManual annotationGene organization
Relaxosome-missing IME Tn6483 KY883660 qnrVC1, arr2, dfrA22e, qacED1, and sul1
Relaxosome-missing IME Tn6487 MF344569 None
Relaxosome-missing IME Tn6562 CP027478 cop
Relaxosome-missing IME Tn6565 LT969519 None
Relaxosome-missing IME Tn6568 KU130294 None
Relaxosome-missing IME Tn6573 CP043398 mcr-11.1
Relaxosome-missing IME Tn6588 CP042860 blaNDM-1, blaOXA-1, bleMBL, aacA4-CR, catB3, lnuF, sul1, aphA6, mph(E), sul2, aph(4)-Ia, aadA2, floR, dfrA12, aphA1, aacC4, qacED1, and arr3 TTAAT
Relaxosome-missing IME Tn6589 CP042857 aacC2, aadA2, ampR, blaNDM-1, bleMBL, catB3, cfr, floR, qacED1, qnrA1, rmtB, sul1, tetR(G), and tetA(G)
Relaxosome-missing IME Tn6590 CP042861 acr3, arsC, arsH, strA, strB, and sul2
Relaxosome-missing IME Tn6722 CP016990 blaTEM-1, blaCTX-M-3, floR, arr3, and aacA4
Relaxosome-missing IME Tn6735 CP014062 ampC
Relaxosome-missing IME Tn6737 CP054855 blaVEB-1, strA, strB, floR, dfrA14b, aadB, cmlA1, qacH, and qnrVC4
Relaxosome-missing IME Tn6779 CP054844 None None
Relaxosome-missing IME Tn6836 CP013067 None
Relaxosome-missing IME Tn6843 AP019193 cop
Relaxosome-missing IME Tn6844b CP054855 tetA(E)
Relaxosome-missing IME Tn6852 HG530068 chrA
Relaxosome-missing IME Tn6855 MK347425 mexCD-oprJ
Relaxosome-missing IME Tn6872 LR134189 None
Relaxosome-missing IME Tn6875 CP031508 None
Relaxosome-missing IME Tn6877 CP021775 blaGES-1, and blaOXA-2
Relaxosome-missing IME Tn6872 LR134189
Relaxosome-missing IME Tn6875 CP031508

References

1.    Guedon G, Libante V, Coluzzi C et al. The obscure world of integrative and mobilizable elements, highly widespread elements that pirate bacterial conjugative systems. Genes (Basel) 2017; 8.
2.    Bellanger X, Payot S, Leblond-Bourget N et al. Conjugative and mobilizable genomic islands in bacteria: evolution and diversity. FEMS Microbiol Rev 2014; 38: 720-60