Acetyl-CoA production by Mediator-bound 2-ketoacid dehydrogenases boosts de novo histone acetylation and is regulated by nitric oxide [Chipseq_H3K27ac_spikein]

Histone modifying enzymes depend on the availability of cofactors, with acetyl-CoA being required for histone acetyltransferase (HAT) activity. The discovery that mitochondrial acyl-CoA producing enzymes are also delivered to the nucleus suggests that high concentrations of metabolites generated locally may impact acetylation of histones and other nuclear substrates and eventually control gene regulation. Here we show that 2-ketoacid dehydrogenases were stably associated with the Mediator complex in macrophages, thus providing a local supply of acetyl-CoA and increasing the generation of hyper-acetylated histone tails. Nitric oxide (NO), which is produced in large amounts in LPS-stimulated macrophages, inhibited both the activity of 2-ketoacid dehydrogenases and their association with Mediator. Consequently, NO reduced de novo histone acetylation at genomic regions with high acetyl-CoA deposition rates. Our findings indicate that a local supply of acetyl-CoA generated by Mediator-bound 2-ketoacid dehydrogenases is required to maximize acetylation of histone tails at sites of elevated HAT activity.