A new look for lysine

Researchers have identified a new modification for the amino acid lysine which introduces a negative charge rather than simply hiding the positive charge, which is what was previously understood. The work is published online this week in Nature Chemical Biology, and suggests that larger changes in protein function can be caused through this modification.

Cellular functions are controlled at many levels, including at the ‘post-translational’ level, after a protein has been created by the ribosome. These modifications typically involve the covalent attachment of small chemical groups or metabolites onto a protein.

Lysine, one of the common amino acids, is a frequent target of these modifications due to its unique chemical reactivity. Acetylation is the attachment of an acetyl group and is a frequent type of modification and can have significant consequences for the modified protein’s function.

Yingming Zhao and colleagues identify a new post-translational modification: the attachment of the metabolite succinate, to lysine to generate succinyl-lysine. Using mass spectrometry data, the team demonstrates this modification on a large number of proteins and in a variety of cell types. Whereas acetylation is thought to simply ‘hide’ the normal positive charge of lysine, this new modification introduces a negative charge and so should be able to cause much larger changes in protein function.