Life without tRNAArg-adenosine deaminase TadA: evolutionary consequences of decoding the four CGN codons as arginine in Mycoplasmas and other Mollicutes.

ABSTRACT: In most bacteria, two tRNAs decode the four arginine CGN codons. One tRNA harboring a wobble inosine (tRNA(Arg)ICG) reads the CGU, CGC and CGA codons, whereas a second tRNA harboring a wobble cytidine (tRNA(Arg)CCG) reads the remaining CGG codon. The reduced genomes of Mycoplasmas and other Mollicutes lack the gene encoding tRNA(Arg)CCG. This raises the question of how these organisms decode CGG codons. Examination of 36 Mollicute genomes for genes encoding tRNA(Arg) and the TadA enzyme, responsible for wobble inosine formation, suggested an evolutionary scenario where tadA gene mutations first occurred. This allowed the temporary accumulation of non-deaminated tRNA(Arg)ACG, capable of reading all CGN codons. This hypothesis was verified in Mycoplasma capricolum, which contains a small fra

SUBMITTER: Yokobori S 

PROVIDER: S-EPMC3711424 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature