An economic demand-based framework for prioritization strategies in response to transient amino acid limitations

Cells contain disparate amounts of distinct amino acids, each of which has different metabolic and chemical origins, but the supply cost vs demand requirements of each is unclear. Here, using yeast we quantify the restoration-responses after disrupting amino acid supply, and uncover a hierarchically prioritized restoration strategy for distinct amino acids. We comprehensively calculate individual amino acid biosynthetic supply costs, quantify total demand for an amino acid, and estimate cumulative supply/demand requirements for each amino acid. Through this, we discover that the restoration priority is driven by the gross demand for an amino acid, which is itself coupled to low supply costs for that amino acid. Demand from metabolic requirements dominate the demand-pulls for an amino acid, as exemplified by the largest restoration response upon disrupting arginine supply. Collectively, this demand-driven framework that drives the amino acid economy can identify novel amino acid responses, and help design metabolic engineering applications. How cells prioritize restoring amino acids when supply is limited is unknown. Here, using budding yeast, the authors build an economic framework to explain prioritization strategies and find that the amino acid economy is driven by demand for low-cost amino acids.