Heterologous biosynthesis offers a new way to capture the medicinal properties presented by complex natural products. In this study, production of 6-deoxyerythronolide B (6dEB), the polyketide precursor to the antibiotic erythromycin, was used to probe the heterologous pathways needed for Escherichia coli-derived biosynthesis. More specifically, the heterologous proteins responsible for 6dEB production were varied by adjusting their respective gene dosage levels. In this way, heterologous components required for posttranslational modification, 6dEB biosynthesis, and substrate provision were adjusted in expression levels to observe the relative effect each has on final heterologous biosynthesis. The results indicate that both the biosynthetic and substrate provision heterologous proteins impact 6dEB formation to a greater extent when compared with posttranslational modification and suggest these components for future protein and metabolic engineering.