Proteins of Diverse Function and Subcellular Location Are Lysine Acetylated in Arabidopsis    

Abstract

Acetylation of the «-amino group of lysine (Lys) is a reversible posttranslational modification recently discovered to be widespread, occurring on proteins outside the nucleus, in most subcellular locations in mammalian cells. Almost nothing is known about this modification in plants beyond the well-studied acetylation of histone proteins in the nucleus. Here, we report that Lys acetylation in plants also occurs on organellar and cytosolic proteins. We identified 91 Lys-acetylated sites on 74 proteins of diverse functional classes. Furthermore, our study suggests that Lys acetylation may be an important posttranslational modification in the chloroplast, since four Calvin cycle enzymes were acetylated. The plastid-encoded large subunit of Rubisco stands out because of the large number of acetylated sites occurring at important Lys residues that are involved in Rubisco tertiary structure formation and catalytic function. Using the human recombinant deacetylase sirtuin 3, it was demonstrated that Lys deacetylation significantly affects Rubisco activity as well as the activities of other central metabolic enzymes, such as the Calvin cycle enzyme phosphoglycerate kinase, the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase, and the tricarboxylic acid cycle enzyme malate dehydrogenase. Our results demonstrate that Lys acetylation also occurs on proteins outside the nucleus in Arabidopsis (Arabidopsis thaliana) and that Lys acetylation could be important in the regulation of key metabolic enzymes.

Modulation of Protein Phosphorylation, N-Glycosylation and Lys-Acetylation in Grape (Vitis vinifera) Mesocarp and Exocarp Owing to Lobesia botrana Infection

“…Conversely, phosphorylated proteins were mainly localized to the nucleus and cytosol. Lys-acetylated proteins were localized in several cellular compartments in agreement with previous findings regarding a broad range of functions for this modification (37,38).…”

“…2B). Even though we identified more Lysacetylation sites than previous plant acetylproteome studies (37,38), it is important to mention that iTRAQ can interfere with the Lys-acetylation immunoprecipitation efficiency, as previously reported (39) and this can reduce the number of identified Lys-acetylated peptides. The distribution of the 603 phosphorylation sites identified in the exocarp, and the 878 sites detected in the mesocarp was, respectively 89%/92% ( p S); 10%/7% ( p T); and 1%/1% ( p Y) (Fig.…”

“…4E). In a previous paper (37), only a very weak motif could be detected, with the acetylated lysines surrounded by Gly, Ala, Leu, and Arg amino acids. To our knowledge the acK-Y motif is the first report of the acetylation motif in plants, even though it has already been described for human (51).…”

The Arabidopsis Class II Sirtuin Is a Lysine Deacetylase and Interacts with Mitochondrial Energy Metabolism

“…Two recent studies identified the first organellar Lysacetylated proteins in Arabidopsis (Finkemeier et al, 2011;Wu et al, 2011). Among these proteins were several plastidial proteins but only a few mitochondrial proteins, such as cytochrome c, the a subunit of the ATP synthase complex, and AAC1.…”

“…In plants, Lys acetylation was, until recently, mainly thought to occur on histone proteins as regulatory mechanism for transcription and chromatin functions (Hollender and Liu, 2008). However, several central metabolic enzymes of diverse subcellular compartments were recently discovered to be Lys acetylated in Arabidopsis (Arabidopsis thaliana), and in vitro deacetylation tests confirmed that Lys acetylation affects enzyme activities and protein functions (Finkemeier et al, 2011;Wu et al, 2011). Although even organellar-encoded proteins, such as the b subunit of the ATP synthase and the large subunit of Rubisco, have been identified as Lys acetylated in Arabidopsis, it is as yet unclear which enzymes regulate this modification in mitochondria and chloroplasts of plants.…”