Chapter 13 Translation in archaea

Abstract

Publisher Summary Macromolecules involved in translation processes possess the ubiquity and the high degree of evolutionary stability required for inferring the deepest genealogical relationships among (extant) life forms. By contrast, eucaryal mRNAs (messenger ribo nucleic acid) are translated after extensive modifications of the primary transcripts that yield mature monocistronic mRNAs. The sequences of nearly one hundred archaeal tRNAs (transfer RNA) have been deduced from either cloned genes or the purified tRNA species. Compared to their bacterial and eucaryal homologs, archaeal tRNAs systematically lack ribothymidine and 7-methylguanosine. Archaeal genomes contain clusters of co-operating genes often resembling those of bacteria in both gene composition and gene order. The archaeal clusters, however, are not strictly comparable to bacterial operons. Judging from the nucleotide sequences of cloned protein coding genes, Shine-Dalgarno mRNA-ribosome recognition appears to be a frequent although not generalized feature of archaea. A more difficult task is to identify features conferring heat stability to factors from the hyperthermophilic archaea. Within bacteria that primitive organization has been maintained across the vast evolutionary distance separating E. coli and T. maritima.