Chemical proteomic approaches to investigate N-myristoylation

The protein lipidation event N-myristoylation is catalyzed by the N-myristoyltransferase (NMT) enzymes and occurs on over 200 proteins with N-terminal glycines. The modification controls the localization, stability, function and interactions of its substrate proteins and has been implicated in the regulation of multiple biological processes and disease pathologies. Understanding how the N-myristoylated proteome is altered in these pathologies and in response to pharmacological NMT inhibition is therefore critical to understand how N-myristoylation regulates basic biology and how its pharmacological inhibition may be optimally leveraged in clinical settings. Chemical proteomic approaches have emerged as powerful methods to profile protein post-translational modifications, including lipidation, on a proteome-wide scale. This chapter describes two complementary chemical proteomic methods to assess N-myristoylation. The metabolic labelling approach is based on the uptake and incorporation of bio-orthogonal myristic acid analogues into NMT substrates, allowing the selective labelling, enrichment and detection of these proteins. In contrast, the second method is based on the ability of Sortase A to modify N-terminal glycines with a substrate peptide, allowing the incorporation of an enrichment handle in NMT substrates lacking N-myristoylation, for example due to pharmacological NMT inhibition. Detailed, up-to-date protocols for both chemical proteomic approaches are described in this chapter and encompass all steps of the workflows, including cell treatment, sample preparation and data analysis.