High expression of a synthetic gene encoding potato alpha-glucan phosphorylase in Aspergillus niger

We describe the successful heterologous expression of the Solanum tuberosum alpha-glucan phosphorylase (GP) gene in Aspergillus niger. Special attention was paid to the influence of different codon usage and A+T content in the coding region on GP protein expression. Use of A. niger-preferred codon usage and lower A+T content in a synthetic gene (GP-syn) resulted in a significant improvement in the level of the GP mRNA and a dramatic increase in the quantity of GP protein produced such that it accounted for approximately 10% of the total soluble protein. We suggest that redesigning the primary DNA sequence encoding a desired protein product can be an extremely effective method for improving heterologous protein production in filamentous fungi.