A1 Refereed original research article in a scientific journal
The plastidial protein acetyltransferase GNAT1 forms a complex with GNAT2, yet their interaction is dispensable for state transitions
Authors: Brünje, Annika; Füßl, Magdalena; Eirich, Jürgen; Boyer, Jean-Baptiste; Heinkow, Paulina; Neumann, Ulla; Konert, Minna; Ivanauskaite, Aiste; Seidel, Julian; Ozawa, Shin-Ichiro; Sakamoto, Wataru; Meinnel, Thierry; Schwarzer, Dirk; Mulo, Paula; Giglione, Carmela; Finkemeier, Iris
Publisher: Elsevier BV
Publication year: 2024
Journal: Molecular and Cellular Proteomics
Journal name in source: Molecular & Cellular Proteomics
Journal acronym: Mol Cell Proteomics
Article number: 100850
Volume: 23
Issue: 11
ISSN: 1535-9476
eISSN: 1535-9484
DOI: https://doi.org/10.1016/j.mcpro.2024.100850
Web address : https://doi.org/10.1016/j.mcpro.2024.100850
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/458337345
Protein N-acetylation is one of the most abundant co- and post-translational modifications in eukaryotes, extending its occurrence to chloroplasts within vascular plants. Recently, a novel plastidial enzyme family comprising eight acetyltransferases that exhibit dual lysine and N-terminus acetylation activities was unveiled in Arabidopsis. Among these, GNAT1, GNAT2, and GNAT3 reveal notable phylogenetic proximity, forming a subgroup termed NAA90. Our study focused on characterizing GNAT1, closely related to the state transition acetyltransferase GNAT2. In contrast to GNAT2, GNAT1 did not prove essential for state transitions and displayed no discernible phenotypic difference compared to the wild type under high light conditions, while gnat2 mutants were severely affected. However, gnat1 mutants exhibited a tighter packing of the thylakoid membranes akin to gnat2 mutants. In vitro studies with recombinant GNAT1 demonstrated robust N-terminus acetylation activity on synthetic substrate peptides. This activity was confirmed in vivo through N-terminal acetylome profiling in two independent gnat1 knockout lines. This attributed several acetylation sites on plastidial proteins to GNAT1, reflecting a subset of GNAT2's substrate spectrum. Moreover, co-immunoprecipitation coupled to mass spectrometry revealed a robust interaction between GNAT1 and GNAT2, as well as a significant association of GNAT2 with GNAT3 - the third acetyltransferase within the NAA90 subfamily. This study unveils the existence of at least two acetyltransferase complexes within chloroplasts, whereby complex formation might have a critical effect on the fine-tuning of the overall acetyltransferase activities. These findings introduce a novel layer of regulation in acetylation-dependent adjustments in plastidial metabolism.
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Funding information in the publication:
This work was supported by the Professorinnenprogramm of the University of Muenster and funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Projektnummern FI1655/4-1, 445970965, 469950637, 507704013 to I.F.. Further support was provided by Deutscher Akademischer Austauschdienst (DAAD) within the Programme for Project-Related Personal Exchange, the European Research Area-Coordinated Action in Plant Sciences (ERA-CAPS) Research Programme ‘KatNat’, the Research Council of Finland 321616, 355787 and 330083 to P.M., A.I. and M.K.. Further support was provided by the French National Research Agency (ANR) by KatNat (ERA-CAPS, ANR-17-CAPS-0001-01) and CanMore (France-Germany PRCI, ANR-20 CE92-0040) to C.G., T.M., and J.B.B. This work has benefited from the support from a French State grant (Saclay Plant Sciences, reference n° ANR-17-EUR-0007, EUR SPS-GSR) under a France 2030 program (reference n° ANR-11-IDEX-0003), and from the facilities and expertise of the I2BC proteomic platform (Proteomic-Gif, SICaPS) supported by IBiSA, Ile de France Region, Plan Cancer, CNRS and Paris-Saclay University and from COST Action CA20113, supported by COST (European Cooperation in Science and Technology). Further support was provided by the Grants-in-Aid for Scientific Research from Japan Society for the Promotion of Science KAKENHI 23H04959 to WS and by the RECTOR program in Okayama University, Japan, to S.O. and W.S.
