Recent Mobility of Casposons, Self-Synthesizing Transposons at the Origin of the CRISPR-Cas Immunity
Abstract
Casposons are a superfamily of putative self-synthesizing transposable elements that are predicted to employ a homolog of Cas1 protein as a recombinase and could have contributed to the origin of the CRISPR-Cas adaptive immunity systems in archaea and bacteria. Casposons remain uncharacterized experimentally, except for the recent demonstration of the integrase activity of the Cas1 homolog, and given their relative rarity in archaea and bacteria, original comparative genomic analysis has not provided direct indications of their mobility. Here, we report evidence of casposon mobility obtained by comparison of the genomes of 62 strains of the archaeon Methanosarcina mazei. In these genomes, casposons are variably inserted in three distinct sites indicative of multiple, recent gains, and losses. Some casposons are inserted into other mobile genetic elements that might provide vehicles for horizontal transfer of the casposons. Additionally, many M. mazei genomes contain previously undetected solo terminal inverted repeats that apparently are derived from casposons and could resemble intermediates in CRISPR evolution. We further demonstrate the sequence specificity of casposon insertion and note clear parallels with the adaptation m...Continue Reading
References
Genome size reduction through illegitimate recombination counteracts genome expansion in Arabidopsis
CRISPR--a widespread system that provides acquired resistance against phages in bacteria and archaea
Citations
Software Mentioned
Related Concepts
Related Feeds
Archaeogenetics
Recent advances in genomic sequencing has led to the discovery of new strains of Archaea and shed light on their evolutionary history. Discover the latest research on Archaeogenetics here.
CRISPR (general)
Clustered regularly interspaced short palindromic repeats (CRISPR) are DNA sequences in the genome that are recognized and cleaved by CRISPR-associated proteins (Cas). CRISPR-Cas system enables the editing of genes to create or correct mutations. Discover the latest research on CRISPR here.
CRISPR for Genome Editing
Genome editing technologies enable the editing of genes to create or correct mutations. Clustered regularly interspaced short palindromic repeats (CRISPR) are DNA sequences in the genome that are recognized and cleaved by CRISPR-associated proteins (Cas). Here is the latest research on the use of CRISPR-Cas system in gene editing.
CRISPR Ribonucleases Deactivation
CRISPR-Cas system enables the editing of genes to create or correct mutations. This feed focuses on mechanisms that underlie deactivation of CRISPR ribonucleases. Here is the latest research.