The CGA Codon Decoding through Arg-tRNA^ICG Supply Governed by Tad2/Tad3 in Saccharomyces cerevisiae

The CGA codon is a rare codon in _Saccharomyces cerevisiae _and is known to be inefficiently decoded by wobble pairing with Arg-tRNAICG. Experimental consecutive CGA codons cause ribosome stalling to result in a reduction of the encoding protein product. In this study, an additional supply of Arg-tRNA(ACG) genes that produce decoding Arg-tRNAICG recovered the product level from the CGA12-luc reporter, revealing that the product reduction is essentially due to inefficient decoding and deficiency in the tRNA supply. The mature tRNAICG and the precursor tRNAACG ratios examined for cellular tRNA fraction determined that the tRNAICG ratio is maintained at less than 30%, and is responsive to the anticodon first adenosine deamination enzyme, Tad2/Tad3, expression level.