Every time a cell ramps up glycolysis — burning more glucose for energy — it may be simultaneously rewriting its own gene expression program. A newly characterized biochemical modification suggests that the metabolite pyruvate doesn't simply flow onward to the mitochondria; it can chemically tag proteins, including histones, creating a direct molecular bridge between energy metabolism and epigenetic control. This challenges the long-standing assumption that metabolic state and transcriptional regulation communicate primarily through indirect signaling cascades.
Published in Nature Metabolism, this work systematically maps lysine pyruvylation (Kpy) — the covalent addition of a pyruvyl group to lysine residues — across the mammalian proteome. Using biochemical and mass-spectrometry-based proteomic approaches, the researchers identified 88 discrete Kpy sites in mammalian cells. Critically, Kpy levels fluctuate in direct response to changes in glycolytic flux and intracellular pyruvate concentrations, establishing the modification as metabolically dynamic rather than constitutive. The team also identified the enzymatic machinery governing the cycle: histone acetyltransferase 1 (HAT1) and the transcriptional coactivator p300 (EP300) install the pyruvyl mark, while the mitochondrial deacylase SIRT3 erases it — placing Kpy within a regulated, reversible system.
This finding fits within a rapidly expanding framework of acyl-lysine modifications — including succinylation, malonylation, and the same group's earlier discovery of lactylation — that together suggest metabolites function as direct epigenetic writers, not merely as passive energy substrates. The involvement of SIRT3, a longevity-associated sirtuin responsive to NAD⁺ levels, is particularly intriguing: it positions Kpy as potentially sensitive to dietary, fasting, or aging-related shifts in metabolic state. That said, this is foundational biochemistry in cell culture and requires validation in physiological animal models and human tissue before functional claims about disease or aging can be made. The identification of 88 substrate sites is a starting point, not a complete landscape. Still, as a systematic characterization of a previously uncharacterized PTM with defined enzymes and demonstrated metabolic responsiveness, this is a genuinely significant mechanistic advance.