Gene invasion in distant eukaryotic lineages: discovery of mutually exclusive genetic elements reveals marine biodiversity
The ISME Journal (2013) 7, 1764–1774
http://www.nature.com/ismej/journal/v7/n9/full/ismej201370a.html
Adam Monier, et al.
Inteins are rare, translated genetic parasites mainly found in bacteria and archaea, while spliceosomal introns are distinctly eukaryotic features abundant in most nuclear genomes.
Using targeted metagenomics, we discovered an intein in an Atlantic population of the photosynthetic eukaryote, Bathycoccus, harbored by the essential spliceosomal protein PRP8 (processing factor 8 protein). …
We hypothesize that intein propagation is facilitated by marine viruses; and, while intron gain is still poorly understood, presence of a spliceosomal intron where a locus lacks an intein raises the possibility of new, intein-primed mechanisms for intron gain.
Keywords: invasive elements; inteins; polymorphic introns; horizontal transfer; metagenomics; viridiplantae
The origins and distributions of introns and inteins remain one of the greatest mysteries of molecular and evolutionary biology.
Spliceosomal introns are distinctly eukaryotic features abundant in almost all nuclear genomes.
These non-coding elements interrupt coding regions (exons) of genes and are excised from the nascent mRNA prior to translation.
In contrast, inteins (internal protein) are much rarer genetic elements found in protein-coding genes from all three domains of life and viruses.
These in-frame intervening sequences are in coding regions of genes and are translated as part of the host protein. After self-catalyzed excision by the intein, the host protein flanking regions known as exteins (external protein) are ligated by a peptide bond. This intein-mediated process has been dubbed protein-splicing and maintains host protein functional integrity.