Unconventional codon reading by Mycoplasma mycoides tRNAs as revealed by partial sequence analysis.

Continuing our investigation of the tRNA genes and gene products in Mycoplasma mycoides, we report the sequence of the gene for tRNALeu (CAA) as well as partial primary structures of the following tRNAs: Leu (CAA), Leu (UAG), Arg (UCU), Thr (AGU) and Ile (CAU). It is suggested that in M. mycoides, at least some of the family codon boxes are read by only one tRNA each, using an unconventional method which does not discriminate between the nucleotides in the third codon position. M. mycoides is the first free-living organism known to use an unconventional method of this kind.