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

Abstract

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.

Dynamic play between human N-α-acetyltransferase D and H4-mutant histones: Molecular dynamics study

“…This indicates that in these MTs, the residue network of the hNatD is disrupted significantly. Recently, Ho et al have investigated the catalytic efficiency of hNatD for pentapeptide of H4 WT and MT tails (Ho & Huang, 2021). Their finding shows that the catalytic efficiency of N-α-acetylation of MT histone tails was remarkably reduced.…”

“…Figure 1 illustrates the acetylation of H4/H2A by hNatD. Recently, how the activity and catalytic efficiency of hNatD are altered under the influence of WT and MTs pentapetides binding to hNatD has been reported (Ho & Huang, 2021). However, the molecular level understanding of H4 (WT & MTs) binding dynamics still lacks.…”

De novo methylation of histone H3K23 by the methyltransferases EHMT1/GLP and EHMT2/G9a

“…While these enzymes were already known to be promiscuous on both non-histone and histone targets [38], [39], this work draws attention to the phenomena that multiple, biologically distinct, histone methylation marks can be catalyzed by the same HMTs in vivo [40], [41]. This work could also shed light on combinatorial post-translational modi cation states involving these newly identi ed targets in vivo, as well as provide new insights into mechanisms of PTM cross-talk and how oncohistones can impart changes in the epigenome [42], [43]. More interestingly, in vivo perturbations in EHMT1/GLP and EHMT2/G9a have been implicated in many cellular processes including autophagy [44], DNA methylation, [35], [45], hypoxia [46], tumor suppression [47]- [50], chromatin remodeling [20], and synaptic plasticity [51] to name a few, and homozygous loss of EHMT1/GLP results in embryonic lethality in mice [52].…”

“…The EHMT1/GLP and EHMT2/G9a methyltransferases are being pursued as targets for drug development, particularly as potential anti-cancer therapeutics [48], [53]- [57] including the inhibitor used in this study, UNC0642, as well as multiple additional agents, including a recently described dual inhibitor of EHMT2/G9a and the DNA methyltransferase DNMT1 [45]. These enzymes have been targeted largely due to their well-characterized role in mediating H3K9 methylation, an important heterochromatic mark that is often used by cancer cells to repress large chromatin blocks and repress expression of key tumor suppressor genes and pathways [19], [34], [41], [43]. However, based on the current work, it will be important to assess the impact of such EHMT1/GLP and EHMT2/G9a inhibitors on methylation at other histone lysine methylation modi cations including at H3K18, H3K23, and H3K27, since these would represent on-target modi cations that, upon EHMT1/GLP or EHMT2/G9a inhibition, may have unanticipated consequences apart from inhibiting H3K9 methylation alone.…”

Oncohistones: Exposing the nuances and vulnerabilities of epigenetic regulation

“…Also prevalent are mutations on the far N termini of H2A and H4, especially those at H4S1, R3, G4, and H2AS1 and R3 (Nacev et al, 2019). Peptides bearing mutations at these residues show reduced acetylation by the H2A/H4-specific N-acetyltransferase NatD (Ho and Huang, 2022). Activity decreases result from Review decreased K m values of the mutant histone peptides (Ho and Huang, 2022), suggesting compromised binding consistent with the NatD crystal structure that reveals a narrow binding channel likely to be blocked by substrate N-terminal mutation (Magin et al, 2015).…”