N-Terminal Acetylation and Protein Degradation Pathways

N-terminal acetylation constitutes one of the most prevalent modifications in eukaryotic cells, yet its global influence on protein turnover has only recently become clear. By capping the α-amino group of nascent polypeptides, N-terminal acetylation can mask degron signals, thereby shielding proteins from recognition by degradation machinery. This modification is co-translationally installed by a family of N-terminal acetyltransferases (NATs) that act with high substrate specificity determined by the N-terminal sequence context. In parallel, the ubiquitin-proteasome system orchestrates selective protein degradation through E3 ubiquitin ligases that identify degron motifs, attach ubiquitin chains and direct substrates to the proteasome. The interplay between N-terminal acetylation and degron exposure forms a regulatory nexus governing protein stability, cellular signalling and stress responses. Dysregulation of this balance has been implicated in processes from development to neurodegeneration and ageing, highlighting its global significance and therapeutic potential.

Research from Nature Portfolio

Recent studies have demonstrated that loss of a major NAT complex leads to accelerated degradation of specific protein subsets through direct recognition by a UBR family ligase complex, revealing that unacetylated N-termini bearing methionine followed by a hydrophobic residue act as high-priority degrons. Functional assays in human cells and in Drosophila models link this interplay to reduced longevity, motility defects and male sterility, while targeted modulation of key substrates reverses these phenotypes, underscoring the physiological importance of N-terminal acetylation as a protective mechanism.

Another investigation has employed a multiplex CRISPR screening platform to assign E3 ligases to their cognate substrates at scale. By combining pools of full-length proteins with site-saturation mutagenesis, the study refined known C-degron pathways, uncovered new substrate–ligase pairs and demonstrated compatibility with diverse substrate stabilities. This high-throughput approach accelerates mapping of specificity determinants within the ubiquitin-proteasome system, offering insights into the molecular logic of degron recognition.

N-Terminal Acetylation and Protein Degradation Pathways publication trend

The graph below shows the total number of articles in n-terminal acetylation and protein degradation pathways across all publications each year (not limited to Nature Index journals).

Technical terms

N-terminal acetylation: The covalent addition of an acetyl group to the free amino terminus of a protein, often affecting its stability and interactions.

Degron: A short sequence or structural motif within a protein recognised by ubiquitin ligases that marks the protein for degradation.

Ubiquitin-proteasome system: A cellular pathway in which proteins are tagged with ubiquitin molecules and subsequently degraded by the proteasome complex.

N-terminal acetyltransferases (NATs): Enzymes that catalyse N-terminal acetylation, determining substrate selection based on the initial amino acid sequence.

E3 ubiquitin ligases: Enzymes that confer specificity in the ubiquitin-proteasome system by recognising degrons and mediating ubiquitin transfer to substrates.

References

1. N-terminal acetylation shields proteins from degradation and promotes age-dependent motility and longevity. Nature Communications (2023).
2. DEGRONOPEDIA: a web server for proteome-wide inspection of degrons. Nucleic Acids Research (2024).
3. Defining E3 ligase–substrate relationships through multiplex CRISPR screening. Nature Cell Biology (2023).
4. Elucidation of E3 ubiquitin ligase specificity through proteome-wide internal degron mapping. Molecular Cell (2023).
5. Spotlight on protein N-terminal acetylation. Experimental & Molecular Medicine (2018).
6. N‐terminal modifications of cellular proteins: The enzymes involved, their substrate specificities and biological effects. Proteomics (2015).