Homeostasis of the biosynthetic metabolome.

Metabolite concentrations vary across conditions and such metabolome changes are relevant for metabolic and gene regulation. Here, we used LC-MS/MS to explore metabolite concentration changes in . We measured 101 primary metabolites in 19 experimental conditions that include various nutrients and stresses. Many metabolites showed little variation across conditions and only few metabolites correlated with the growth rate. The least varying metabolites were nucleotides (e.g. UTP had 10% variation) and amino acids (e.g. methionine had 13% variation). These results show that maintains protein and RNA building blocks within narrow concentration ranges, thus indicating that many feedback mechanisms in biosynthetic pathways contribute to end-product homeostasis.