Effects of Oncohistone Mutations and PTM Crosstalk on the N-Terminal Acetylation Activities of NatD.

Acetylation at the α-N-terminus (Nα) is the most abundant modification detected on histone H4 and H2A, which is catalyzed by N-terminal acetyltransferase D (NatD or NAA40). Histone H4 and H2A contain an identical N-terminal SGRGK sequence that is enriched with post-translational modifications (PTMs) and frequently occurred oncogenic mutations known as "oncohistone" mutations. However, there is a lack of information on how oncohistone mutations and other PTMs affect NatD-catalyzed acetylation. Herein, we determined how the local chemical environment on the N-terminal SGRGK sequence impacts NatD-catalyzed Nα-acetylation on histone H4/H2A. Our studies indicate that all oncohistone mutations at SGRG suppressed NatD-catalyzed acetylation. Meanwhile, H4 Ser1 phosphorylation and Arg3 methylation negatively impact the NatD-mediated acetylation, but the Lys5 acetylation only has a marginal effect. This work reveals the impacts of oncohistone mutations on NatD activity and unravels the crosstalk between NatD and PTMs, implying potential regulatory mechanism of NatD and highlighting different avenues to interrogate the NatD-mediated pathway in the future.