Modified tRNA and nucleoside structures (adapted from [78]).

Cloverleaf secondary structure representation of tRNA showing post-transcriptional nucleoside modifications that are conserved among bacteria and archaea in both identity and position. The structures of respective conserved modified nucleosides are highlighted in grey. Methyl and acetyl groups are shown in red and dark red, respectively; sulfur in yellow; and the threonylcarbamoyl group in blue.