Quantitative proteomic analysis of the lysine acetylome reveals diverse SIRT2 substrates

Sirtuin 2 (SIRT2) is a NAD+-dependent deacetylase, which regulates multiple biological processes, including genome maintenance, aging, tumor suppression, and metabolism. While a number of substrates involved in these processes have been identified, the global landscape of the SIRT2 acetylome remains unclear. Using a label-free quantitative proteomic approach following enrichment for acetylated peptides from SIRT2-depleted and SIRT2-overexpressing HCT116 human colorectal cancer cells, we identified a total of 2,846 unique acetylation sites from 1414 proteins. 896 sites from 610 proteins showed a > 1.5-fold increase in acetylation with SIRT2 knockdown, and 509 sites from 361 proteins showed a > 1.5-fold decrease in acetylation with SIRT2 overexpression, with 184 proteins meeting both criteria. Sequence motif analyses identified several site-specific consensus sequence motifs preferentially recognized by SIRT2, most commonly KxxxxK(ac). Gene Ontology, KEGG, and MetaCore pathway analyses identified SIRT2 substrates involved in diverse pathways, including carbon metabolism, glycolysis, spliceosome, RNA transport, RNA binding, transcription, DNA damage response, the cell cycle, and colorectal cancer. Collectively, our findings expand on the number of known acetylation sites, substrates, and cellular pathways targeted by SIRT2, providing support for SIRT2 in regulating networks of proteins in diverse pathways and opening new avenues of investigation into SIRT2 function.