pyruvylation

Pyruvylation is a post-synthetic modification in which a pyruvate moiety is covalently attached to a molecule, most often to a sugar residue within polysaccharides or glycoproteins. The modification introduces a pyruvate-derived functional group that carries a carboxylate and a ketone, adding negative charge and altering chemical reactivity and three-dimensional conformation of the target.

Biological occurrence of pyruvylation has been observed in bacterial surface polysaccharides and in certain plant and fungal glycans. It can modify the antigenic properties of capsules and O-antigens, influencing interactions with host immune factors and lectins, as well as biofilm formation and virulence in some bacteria. The exact prevalence and distribution of pyruvylated glycans vary across taxa and tissues.

Biosynthesis and chemistry involve pyruvyltransferase enzymes that transfer a pyruvate unit to specific hydroxyl groups on sugar residues. The pyruvate donor is typically a derivative of pyruvate, and the resulting linkage can be O- or C-pyruvyl, depending on enzyme specificity and substrate context. Pyruvylated sugars can be detected by mass spectrometry and NMR, and in some systems by antibodies that recognize the pyruvylated epitope. The modification is relatively stable under physiological conditions but can be labile under certain chemical treatments in some glycan contexts.

Functional significance of pyruvylation includes altered surface charge, conformation, and interaction patterns of glycoconjugates, which can modulate receptor binding and immune recognition. In bacteria, these changes may influence capsule integrity, host interactions, and immune evasion, while in other organisms pyruvylated glycans can affect cell wall properties and glycoprotein function.