General Information/Overview
Overview
The idea that many prokaryotic genomes are mosaic, composed of a "central genome backbone" of essential and house-keeping genes (the core genome) interspersed with DNA segments constituting the "mobilome" (a variety of accessory genes that form part of the pan-genome)(Fig.1.1), is now common currency [1][2].
The mobilome embraces several types of genetic units which, as their collective name indicates, can move from place to place in a particular genome or from cell to cell. These Mobile Genetic Elements (MGE) can be divided into two major groups: those, such as plasmids and bacteriophages, that are transmissible from cell to cell (the intercellular MGE), and those that cannot themselves undergo transfer but which are transferred following integration into members of the first group (the intracellular MGE).
Intracellular MGE or Transposable Elements (TE) include transposons (Tn) and Insertion Sequences (IS) but can embrace integrons (In) [3][4] and introns [5][6][7][8].
Originally, Tn were distinguished from IS since they carry passenger (also called cargo) genes not involved in catalyzing or regulating TE movement. Most eukaryotic DNA transposons have relatives among the prokaryotic IS (see [9]) and it is not surprising that a variety of these elements carrying passenger genes are now also being identified [10][11].
Prokaryotes harbor a host of such elements as well as several types of structure possessing characteristics of both groups (e.g. Integrative Conjugative Elements (ICE), originally called conjugative transposons, as well as other types of non-conjunctive genomic islands) [12][13][14].

Bibliography
- ↑ Medini et al.. The microbial pan-genome. Current opinion in genetics & development. 2005. 15. pp. 589-94. doi: 10.1016/j.gde.2005.09.006. PMID: 16185861.
- ↑ Tettelin et al.. Comparative genomics: the bacterial pan-genome. Current opinion in microbiology. 2008. 11. pp. 472-7. doi: 10.1016/j.mib.2008.09.006. PMID: 19086349.
- ↑ Escudero et al.. The Integron: Adaptation On Demand. Microbiology spectrum. 2015. 3. pp. MDNA3-0019-2014. doi: 10.1128/microbiolspec.MDNA3-0019-2014. PMID: 26104695.
- ↑ Escudero et al.. Unmasking the ancestral activity of integron integrases reveals a smooth evolutionary transition during functional innovation. Nature communications. 2016. 7. pp. 10937. doi: 10.1038/ncomms10937. PMID: 26961432.
- ↑ Craig NL, Chandler M, Gellert M, Lambowitz A, Rice PA, Sandmeyer S. Mobile DNA III. 3rd ed. Washington, DC: ASM; 2015.
- ↑ Lambowitz & Belfort. Mobile Bacterial Group II Introns at the Crux of Eukaryotic Evolution. Microbiology spectrum. 2015. 3. pp. MDNA3-0050-2014. doi: 10.1128/microbiolspec.MDNA3-0050-2014. PMID: 26104554.
- ↑ Zimmerly & Semper. Evolution of group II introns. Mobile DNA. 2015. 6. pp. 7. doi: 10.1186/s13100-015-0037-5. PMID: 25960782.
- ↑ Zimmerly & Wu. An Unexplored Diversity of Reverse Transcriptases in Bacteria. Microbiology spectrum. 2015. 3. pp. MDNA3-0058-2014. doi: 10.1128/microbiolspec.MDNA3-0058-2014. PMID: 26104699.
- ↑ Hickman et al.. Integrating prokaryotes and eukaryotes: DNA transposases in light of structure. Critical reviews in biochemistry and molecular biology. 2010. 45. pp. 50-69. doi: 10.3109/10409230903505596. PMID: 20067338.
- ↑ Bao et al.. New superfamilies of eukaryotic DNA transposons and their internal divisions. Molecular biology and evolution. 2009. 26. pp. 983-93. doi: 10.1093/molbev/msp013. PMID: 19174482.
- ↑ Bao & Jurka. Homologues of bacterial TnpB_IS605 are widespread in diverse eukaryotic transposable elements. Mobile DNA. 2013. 4. pp. 12. doi: 10.1186/1759-8753-4-12. PMID: 23548000.
- ↑ Burrus & Waldor. Shaping bacterial genomes with integrative and conjugative elements. Research in microbiology. 2004. 155. pp. 376-86. doi: 10.1016/j.resmic.2004.01.012. PMID: 15207870.
- ↑ Dobrindt et al.. Genomic islands in pathogenic and environmental microorganisms. Nature reviews. Microbiology. 2004. 2. pp. 414-24. doi: 10.1038/nrmicro884. PMID: 15100694.
- ↑ Guérillot et al.. Modular evolution of TnGBSs, a new family of integrative and conjugative elements associating insertion sequence transposition, plasmid replication, and conjugation for their spreading. Journal of bacteriology. 2013. 195. pp. 1979-90. doi: 10.1128/JB.01745-12. PMID: 23435978.
How to Cite?
TnPedia Team. (2025). TnPedia: General Information on Prokaryotic Elements. Zenodo. https://doi.org/10.5281/zenodo.15548171