Functional analysis of codon bias in the alcohol dehydrogenase gene of Drosophila melanogaster

Codon bias and its effect on protein production was studied using the model organism Drosophila melanogaster. Seven preferred leucine codons in the alcohol dehydrogenase (Adh) gene were changed to unpreferred codons. This gene (7-Up) was microinjected into a line of flies to create mutants carrying the mutant gene. Total soluble protein was isolated and assayed for total protein present and activity level of the enzyme. Ten control lines with the wildtype Adh gene and twelve mutant lines with the 7-Up gene showed average activity levels of 112.8 +/- 28.8 and 124.1 +/- 57.3 mumol NAD+ reduced per minute per mug of protein x 100, respectively. These results indicate that increasing codon bias artificially has no effect on protein production, possibly due to saturated tRNA pools in the cell.