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Proteomics. 2015 Jul;15(14):2426-35. doi: 10.1002/pmic.201500025. Epub 2015 Jun 18.

Molecular identification and functional characterization of the first Nα-acetyltransferase in plastids by global acetylome profiling.

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Department of Plant Molecular Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany.
Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Gif-sur-Yvette, France.
Hartmut Hoffmann-Berling International Graduate School, University of Heidelberg, Heidelberg, Germany.
Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies gGbmH, Heidelberg, Germany.


Protein N(α) -terminal acetylation represents one of the most abundant protein modifications of higher eukaryotes. In humans, six N(α) -acetyltransferases (Nats) are responsible for the acetylation of approximately 80% of the cytosolic proteins. N-terminal protein acetylation has not been evidenced in organelles of metazoans, but in higher plants is a widespread modification not only in the cytosol but also in the chloroplast. In this study, we identify and characterize the first organellar-localized Nat in eukaryotes. A primary sequence-based search in Arabidopsis thaliana revealed seven putatively plastid-localized Nats of which AT2G39000 (AtNAA70) showed the highest conservation of the acetyl-CoA binding pocket. The chloroplastic localization of AtNAA70 was demonstrated by transient expression of AtNAA70:YFP in Arabidopsis mesophyll protoplasts. Homology modeling uncovered a significant conservation of tertiary structural elements between human HsNAA50 and AtNAA70. The in vivo acetylation activity of AtNAA70 was demonstrated on a number of distinct protein N(α) -termini with a newly established global acetylome profiling test after expression of AtNAA70 in E. coli. AtNAA70 predominately acetylated proteins starting with M, A, S and T, providing an explanation for most protein N-termini acetylation events found in chloroplasts. Like HsNAA50, AtNAA70 displays N(ε) -acetyltransferase activity on three internal lysine residues. All MS data have been deposited in the ProteomeXchange with identifier PXD001947 (


Arabidopsis thaliana; AtNAA70; Chloroplast; Nα-acetyltransferase; Plant proteomics

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