adenilyl

Adenylyl, also spelled adenilyl, is a chemical term used to describe the adenylyl group, a moiety derived from adenylic acid (adenosine monophosphate, AMP). In biochemistry it denotes a substituent consisting of an adenosine monophosphate unit attached to another molecule through a phosphate ester linkage. The term is commonly encountered in discussions of reactions that transfer or attach this adenylyl group to substrates.

Adenylylation, or AMPylation, is the covalent attachment of an adenylyl group to a target molecule. In many biological contexts, ATP serves as the donor of the adenylyl group, with pyrophosphate (PPi) released as a byproduct. The resulting product is a substrate-adenylyl (substrate-AMP) compound, in which the substrate is modified by the addition of AMP.

Biological significance and examples of adenylylation are most prominent in enzymology and regulatory biology. Enzymes known as adenylyl transferases catalyze these reactions. Certain bacterial and eukaryotic proteins, including Fic-domain effectors from pathogenic bacteria, AMPylate host proteins to alter their activity, localization, or interactions. For example, some Legionella and Vibrio effectors modify host GTPases or other proteins by AMPylation, influencing processes such as vesicle trafficking and cytoskeletal dynamics.

In terminology, adenylyl constitutes the radical form derived from AMP, distinct from related terms such as adenylate (the anionic form) and adenosine monophosphate itself. The concept is primarily used to describe covalent post-translational modifications and enzyme-mediated transfer reactions involving the AMP moiety.