Protein post-translational modifications in serine synthetic pathway: functions and molecular mechanisms

Serine is a non-essential amino acid, serving as a precursor for other amino acids, lipids, and nucleotide synthesis. Its supply is ensured by two main mechanisms: exogenous uptake and endogenous synthesis. The serine synthesis pathway (SSP) connects glycolysis with the one-carbon cycle and plays an important role in cellular homeostasis by regulating substance synthesis, redox homeostasis, and gene expression. The de novo SSP involves three successive enzymatic reactions catalyzed by phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), and phosphoserine phosphatase (PSPH). Post-translational modifications (PTMs), as essential regulatory mechanisms of proteins, play pivotal roles in physiological and pathological processes. This review focuses on the regulatory mode of PTMs on PHGDH, PSAT1, and PSPH, including phosphorylation, ubiquitination, acetylation, methylation, S-palmitoylation, S-nitrosylation, deamidation, SUMOylation, and lactylation. We summarize how these PTMs participate in the metabolic reprogramming of SSP. It helps us better understand the molecular mechanisms and physiological significance of the PTM network in serine synthetic metabolism, providing guidance for subsequent research and development in the future.