Potential role of the X circular code in the regulation of gene expression

The X circular code is a set of 20 trinucleotides (codons) that has been identified in the protein-coding genes most organisms (bacteria, archaea, eukaryotes, plasmids, viruses). It shown previously important mathematical property being an error-correcting code. Thus, motifs code, i.e. series codons belonging to and called motifs, allow identification maintenance reading frame genes. are significantly enriched genes, but have also many transfer RNA (tRNA) functional regions ribosomal (rRNA), notably peptidyl transferase center decoding center. Here, we investigate potential role as elements First, identify which frequent or rare each domain life (archaea, bacteria, eukaryota) show that, for amino acids with highest codon bias, preferred often codon. We observe correlation between optimal codons/dicodons influence translation efficiency. Then, examined recently published experimental results concerning gene expression levels diverse organisms. approach used analysis according their density ds(X), number per kilobase sequence s. Surprisingly, this simple parameter identifies several unexpected relations expression. For example, minimal three domains life, codon-optimized Furthermore, generally correlates measures efficiency mRNA stability. Taken together, these lead us propose may represent genetic signal contributing correct optimization regulation