deAMPylation

DeAMPylation is the enzymatic removal of an adenosine monophosphate (AMP) group that has been covalently attached to a substrate, reversing the modification known as AMPylation or adenylylation. It is a reversible post-translational modification that can regulate protein activity, interactions, localization, and stability.

The reaction typically cleaves the phosphoester bond linking the substrate’s amino acid residue (often a serine, threonine, or tyrosine) to the phosphate of AMP, releasing free AMP and restoring the unmodified substrate. DeAMPylation is carried out by deAMPylases, enzymes that can be part of the same enzymatic families that perform AMPylation (such as Fic-domain proteins) or other metal-dependent hydrolases. In some systems, certain Fic-domain proteins are bidirectional, capable of both AMPylation and deAMPylation depending on cellular conditions or regulatory cues.

Biological examples show the importance of reversible AMPylation. In mammals, the FicD protein, also known as HYPE, has been reported to catalyze both AMPylation and deAMPylation of the ER chaperone BiP, enabling rapid modulation of protein folding capacity in response to ER stress and calcium signaling. In bacteria, AMPylation is a virulence mechanism used by toxins to modify host proteins, and while the presence and identity of deAMPylases in bacteria are less well characterized, reversibility of AMPylation has been observed in some contexts.

Detection and study of deAMPylation involve mass spectrometry to identify the AMP moiety, biochemical assays with defined substrates, and structural analyses to elucidate active-site mechanisms. DeAMPylation is a key component of the dynamic regulation of protein function by reversible AMPylation.