N-terminal acetylation
Background
N-terminal acetylation (NTA) is a pervasive protein modification in higher eukaryotes but rarely occurs in prokaryotes. NTA is catalyzed by ribosome-tethered N-acetyltransferase (Nat) complexes consisting of a catalytically active and one or more auxiliary subunits (see figure). Because of its co-translational nature and the absence of deacetylases, NTA was supposed to be static and unregulated in eukaryotes. When this project started, the plant N-terminal protein acetylation machinery was barely characterized, and the impact of NTA on protein fate in plants was unknown.
Project Updates
2022 We identify HYPK as a novel NatA complex subunit and demonstrate its facilitating impact on global proteome stability.
2022 We uncover that the NatA complex promotes the stability of the plant proteome by masking a previously unknown N-degron.
2021 In collaboration with Prof. Felix Willmund (University of Kaiserslautern), we provided evidence for a ribosome-tethered N-acetyltransferase in plastids.
2020 We characterize the NAA50 homolog in plants and uncover its crucial function for plant development and the regulation of stress responses.
2020 We show that acetylation of protein N-termini by NatB affects plant growth and immunity towards pathogens.
2020 We identified the plant NAA60 homolog as a plasma membrane-anchored Nat that is required for a successful response towards protein-harming stresses. NAA60 has a broad substrate specificity in vitro and acetylates membrane-associated proteins in planta.
2015 to 2020 We identified the first plastid-localized N-acetyltransferase and contributed in the framework of the ERA-CAPS consortium Kat/Nat to the characterization of the dual active protein acetyltransferase machinery in plastids.
2015 We identified the NatA complex in the reference plant Arabidopsis thaliana and showed that this essential protein complex addresses approximately 40 % of the proteome. The phytohormone ABA down-regulates the abundance of the core NatA subunits, NAA10 and NAA15, which enhances drought tolerance by triggering stomata closure.
