Archaeal Type II Toxin-Antitoxins

Abstract

A few of the bacterial type II TA systems, primarily those involved in translational inhibition, occur widely throughout the archaeal domain. Using a bioinformatic approach, the frequency and distribution of these diverse TA loci were examined within completed genomes of 124 archaea that are distributed fairly evenly throughout the major archaeal phyla. Results for the frequency and diversity of TA loci are summarised for archaea isolated from environmental niches generally characterised by extreme conditions including high temperature, high salt concentrations, high pressures, extremes of pH or strictly anaerobic conditions. No clear correlations were found between the number of TA loci present and either the genome size or particular environmental conditions. Multiple TA loci tend to be concentrated in variable genomic regions where the occurrence of intra- or inter-genomic gene transfer are most prevalent. For members of the Sulfolobales which are uniformly rich in TA loci, a case is made for some TA systems facilitating maintenance of important genomic regions.