Nucleoside modification in archaebacterial transfer RNA

Abstract

Summary The current state of knowledge of nucleoside modification in archaebacterial tRNA is reviewed, and sequence-specific modification patterns are compared with those from eubacteria and eukaryotes. The importance of post-transcriptional modification in tRNA derives from its close association with the role of tRNA in protein synthesis and other regulatory functions, including cellular adaptation to stress. From compositional data from unfractionated tRNA and from 59 archaebacteria isoacceptor sequences, 19 modified nucleosides are presently known, 3 of which are uniquely archaebacterial, compared with more than 60 in eubacteria and eukaryotes. The frequency of modification is similar to eubacteria and lower than in eukaryotes, while a number of specific modifications found are eukaryotic in nature. Compared with tRNA from the other primary kingdoms, the range of nucleoside modifications found in the anticodon loops is low, and is high in the variable loop.