Dual lysine and N‐terminal acetyltransferases reveal the complexity underpinning protein acetylation

• Main Authors: Willy V Bienvenut, Annika Brünje, Jean‐Baptiste Boyer, Jens S Mühlenbeck, Gautier Bernal, Ines Lassowskat, Cyril Dian, Eric Linster, Trinh V Dinh, Minna M Koskela, Vincent Jung, Julian Seidel, Laura K Schyrba, Aiste Ivanauskaite, Jürgen Eirich, Rüdiger Hell, Dirk Schwarzer, Paula Mulo, Markus Wirtz, Thierry Meinnel, Carmela Giglione, Iris Finkemeier
• Format: Article
• Language: English
• Published: Wiley 2020-07-01
• Series: Molecular Systems Biology
• Subjects: acetylome; acetyltransferase; co‐ and post‐translational modifications; plastid; quantitative proteomics
• Online Access: https://doi.org/10.15252/msb.20209464

Abstract Protein acetylation is a highly frequent protein modification. However, comparatively little is known about its enzymatic machinery. N‐α‐acetylation (NTA) and ε‐lysine acetylation (KA) are known to be catalyzed by distinct families of enzymes (NATs and KATs, respectively), although the possibility that the same GCN5‐related N‐acetyltransferase (GNAT) can perform both functions has been debated. Here, we discovered a new family of plastid‐localized GNATs, which possess a dual specificity. All characterized GNAT family members display a number of unique features. Quantitative mass spectrometry analyses revealed that these enzymes exhibit both distinct KA and relaxed NTA specificities. Furthermore, inactivation of GNAT2 leads to significant NTA or KA decreases of several plastid proteins, while proteins of other compartments were unaffected. The data indicate that these enzymes have specific protein targets and likely display partly redundant selectivity, increasing the robustness of the acetylation process in vivo. In summary, this study revealed a new layer of complexity in the machinery controlling this prevalent modification and suggests that other eukaryotic GNATs may also possess these previously underappreciated broader enzymatic activities.