Evolutionary relationship between Halobacterium cutirubrum and eukaryotes determined by use of aminoacyl-tRNA synthetases as phylogenetic probes.

The cross-species reactivities between tRNAs and aminoacyl-tRNA synthetases have been employed as a basis to estimate the relatedness of various prokaryotes to the eukaryotes. The tRNA of Halobacterium cutirubrum, unlike that of other prokaryotes tested, including Agrobacterium tumefaciens, Arthrobacter luteus, Bacillus subtilis, Bacillus stearothermophilus, Escherichia coli, Micrococcus luteus, Myxococcus xanthus, Rhodopseudomonas spheroides, and Thermus aquaticus, was found to share with yeast, rat liver, and wheat germ tRNA a distinct preference for aminoacylation by eukaryotic synthetases from yeast as opposed to prokaryotic synthetases from either E. coli or R. spheroides. These results suggest that phylogenetically H. cutirubrum is more closely related to the eukaryotes than to the eubacteria.