Regulates lysine acetylation levels of plastid proteins related to photosynthesis (PubMed:29061669). Involved in the regulation of the activation state of RuBisCO, which is controlled by lysine acetylation of RuBisCO activase under low-light conditions (PubMed:29061669). Associates with alpha- and beta-tubulins and deacetylate alpha-tubulin (PubMed:22404109). Does not seem to be required for the cellular patterning in the root epidermis (PubMed:16176989). Involved in the regulation of melatonin biosynthesis by catalyzing the deacetylation of N-acetylserotonin to produce serotonin (PubMed:29247559). N-acetylserotonin is methylated by acetylserotonin O-methyltransferase (ASMT) to produce melatonin (N-acetyl-5-methoxytryptamine) (Probable). Deacetylates melatonin to produce 5-methoxytryptamine (PubMed:29247559). In vitro, deacetylates N-acetyltyramine and N-acetyltryptamine to produce tyramine and tryptamine, respectively (PubMed:29247559). H2O + N-acetylserotonin = acetate + serotonin H2O + N-acetyltyramine = acetate + tyramine H2O + N-acetyltryptamine = acetate + tryptamine H2O + melatonin = 5-methoxytryptamine + acetate Binds 1 zinc ion per subunit. Its activity is inhibited by trichostatin A (TSA), a known histone deacetylase inhibitor. Interacts with PP2A2. Expressed in stems, leaves, flowers, siliques and mature seeds. Belongs to the histone deacetylase family.