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Article Dans Une Revue Plant Physiology Année : 2020

NatB-mediated N-terminal acetylation affects growth and biotic stress responses

Résumé

N-terminal acetylation (NTA) is one of the most abundant protein modifications in eukaryotes. In humans, NTA is catalyzed by seven Nα-acetyltransferases (NatA-F and NatH). Remarkably, the plant Nat machinery and its biological relevance remain poorly understood, although NTA has gained recognition as a key regulator of crucial processes such as protein turnover, protein-protein interaction, and protein targeting. In this study, we combined in vitro assays, reverse genetics, quantitative N-terminomics, transcriptomics, and physiological assays to characterize the Arabidopsis NatB complex. We show that the plant NatB catalytic (NAA20) and auxiliary subunit (NAA25) form a stable heterodimeric complex that accepts canonical NatB-type substrates in vitro. In planta, NatB complex formation was essential for enzymatic activity. Depletion of NatB subunits to 30% of the wild-type level in three Arabidopsis T-DNA insertion mutants (naa20-1, naa20-2, and naa25-1) caused a 50% decrease in plant growth. A complementation approach revealed functional conservation between plant and human catalytic NatB subunits, whereas yeast NAA20 failed to complement naa20-1. Quantitative N-terminomics of approximately 1,000 peptides identified 32 bona fide substrates of the plant NatB complex. In vivo, NatB was seen to preferentially acetylate N-termini starting with the initiator methionine followed by acidic amino acids and contributed 20% of the acetylation marks in the detected plant proteome. Global transcriptome and proteome analyses of NatB-depleted mutants suggested a function of NatB in multiple stress responses. Indeed, loss of NatB function, but not NatA, increased plant sensitivity towards osmotic and high-salt stress, indicating that NatB is required for tolerance of these abiotic stressors.
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Dates et versions

hal-02989528 , version 1 (16-11-2020)

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Monika Huber, Willy V Bienvenut, Eric Linster, Iwona Stephan, Laura Armbruster, et al.. NatB-mediated N-terminal acetylation affects growth and biotic stress responses. Plant Physiology, 2020, 182 (2), pp.792-806. ⟨10.1104/pp.19.00792⟩. ⟨hal-02989528⟩
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