tRNA modification profiles in obligate and moderate thermophilic bacilli.

Transfer RNAs (tRNAs) are the most ancient RNA molecules in the cell, modification pattern of which is linked to phylogeny. The aim of this study was to determine the tRNA modification profiles of obligate (Anoxybacillus, Geobacillus, Paragebacillus) and moderate (Bacillus, Brevibacillus, Ureibacillus, Paenibacillus) thermophilic aerobic bacilli strains to find out its linkage to phylogenetic variations between species. LC-MS was applied for the quantification of modified nucleosides using both natural and isotopically labeled standards. The presence of mA and mG modifications at high levels was determined in all species. Relatively high level of iA and mC modification was observed for Paenibacillus and Ureibacillus, respectively. The lowest level of Cm modification was found in Bacillus. The modification msiA and mG were absent in Brevibacillus and Ureibacillus, respectively, while modifications Am and mG were observed only for Ureibacillus. While both obligate and moderate thermophilic species contain Gm, mG and msiA modifications, large quantities of them (especially Gm and msiA modification) were detected in obligate thermophilic ones (Geobacillus, Paragebacillus and Anoxybacillus). The collective set of modified tRNA bases is genus-specific and linked to the phylogeny of bacilli. In addition, the dataset could be applied to distinguish obligate thermophilic bacilli from moderate ones.