Synonymous codon bias is related to gene length in Escherichia coli: selection for translational accuracy?

The level of synonymous codon bias is shown to be positively correlated to gene length in Escherichia co/i genes which are thought to be expressed at similar levels; these are genes whose products are present in multimeric proteins in equimolar amounts. It is argued that the positive correlation could be caused by selection to avoid missense errors during translation. Since the cost of producing a protein is proportional to its length, selection in favor of codons which increase accuracy should be greater in longer genes, and long genes should therefore have higher synonymous codon bias. It is also shown that there is variation in synonymous codon use which is independent of either expression level, gene length, amino acid composition, or chromosomal location. This variation is consistent with selection for translational accuracy but may have other origins.