Apparent operon for a 5S ribosomal RNA gene and for tRNA genes in the archaebacterium Methanococcus vannielii

The nucleotide sequence of the chromosomal segment from Methanococcus vannielii previously shown to encode a gene for 5S ribosomal RNA (rRNA) unlinked to any other rRNA genes (Jarsch et al. 1983) was determined. It was found that the 5S rRNA gene is flanked by seven genes for tRNA (tRNAPro, tRNAThr, tRNATyr, tRNALys and tRNAAsp). Two of the tRNA genes (tRNAAsp and tRNALys) are repeated in the cluster. Only the tRNAPro cistron encodes the 3'-CCA tRNA sequence. The 5S rRNA/tRNA gene cluster probably represents one transcriptional unit. The 5'- and 3'-flanking sequences of the tRNA/5S rRNA gene cluster bear some similarity with initiation and termination signals in eubacteria. There is indication that the different 5S rRNA genes from Methanococcus exhibit sequence polymorphism.