Codon Discrimination in Translation
Transfer RNA in Protein Synthesis
18 Synonymous codon use is non-random. Codons most used in highly transcribed genes, often 19 called optimal codons, typically have high gene counts of matching tRNA genes (tRNA abundance) and 20 promote accurate and/or efficient translation. Non-optimal codons, those least used in highly expressed 21 genes, may also affect translation. In multicellular organisms, codon optimality may vary among tissues. 22 At present however, codon use remains poorly understood in multicellular organisms.
... lar organisms. Here, we studied 23 codon usage of genes highly transcribed in germ line (testis, ovary) and somatic tissues 24 (gonadectomized males and females) of the beetle Tribolium castaneum. The results demonstrate that: 1) 25 the majority of optimal codons were organism-wide, the same in all tissues, and had numerous matching 26 tRNA gene copies (Opt↑tRNA), consistent with translational selection; 2) some optimal codons varied 27 among tissues, suggesting tissue-specific tRNA populations; 3) wobble tRNA were required for 28 translation of certain optimal codons (Opt-codonwobble), possibly allowing precise translation and/or 29 protein folding; and 4) remarkably, some non-optimal codons had abundant tRNA genes (Nonopt-30 codon↑tRNAs), and genes using those codons were tightly linked to ribosomal and stress-response 31 functions. Thus, Nonopt-codon↑tRNAs codons may regulate translation of specific genes. Together, the 32 evidence suggests that codon use and tRNA genes regulate multiple translational processes in beetles. 33