Nucleotide Sequence of the 16S Ribosomal RNA Gene from the Haloalkaliphilic Archaeon (Archaebacterium) Natronobacterium magadii, and the Phylogeny of Halobacteria

The ribosomal RNA operon of the haloalkaliphilic archaeon Natronobacterium magadii was cloned into plasmid vectors. Southern analysis of the cloned genes revealed an organization similar to that of other halobacteria, with rRNA genes linked in the eubacterial order, with a putative tRNA(ala) located in the 16S-23S intergenic space. The primary sequence of the 16S rRNA which was determined by DNA sequencing, can be folded to give a secondary structure consistant with the universal structure proposed by Woese et al. (1983). The 16S rRNA gene is flanked by three sets of inverted repeats which may be involved in 16S rRNA maturation. The nucleotide sequence of the 16S rRNA gene together with previously published sequences was used to produce a phylogenetic tree for the halophilic archaea (halobacteria).