Abstract
In mammalian cells, >25% of proteins are synthesized and exported through the secretory pathway. The pathway complexity, however, obfuscates its impact on the secretion of different proteins. Unraveling its impact on diverse proteins is particularly important, since the pathway is used for biopharmaceutical production. Here we delineate the core secretory pathway functions and integrate them with genome-scale metabolic models of human, mouse, and Chinese hamster ovary (CHO) cells. The resulting reconstructions RECON2.2s, iMM1685s, and iCHO2048s, enable the computation of the cost and machinery demanded by each secreted protein. We predicted metabolic costs and maximum productivities of biotherapeutic proteins and identified protein features that most significantly impact protein secretion. By integrating additional metabolomic, glycoproteomic and ribosomal profiling data, we further found that CHO cells have adapted to reduce expression and secretion of expensive host cell proteins. Finally, the model successfully predicts the increase in titers after silencing a highly expressed selection marker. This work represents a knowledge-base of the mammalian secretory pathway that serves as a novel tool for systems biotechnology.
Footnotes
* Co-first author