Hat2p recognizes the histone H3 tail to specify the acetylation of the newly synthesized H3/H4 heterodimer by the Hat1p/Hat2p complex

The N-terminal acetyltransferase NatA is a heterodimeric complex consisting of a catalytic subunit (Naa10/ARD1) and an auxiliary subunit (Naa15). NatA co-translationally acetylates the N termini of a wide variety of nascent polypeptides. In addition, Naa10 can act independently to posttranslationally acetylate a distinct set of substrates, notably actin. Recent structural studies of Naa10 have also revealed the molecular basis for N-terminal acetylation specificity. Surprisingly, recent reports claim that Naa10 may also acetylate lysine residues of diverse targets, including methionine sulfoxide reductase A, myosin light chain kinase, and Runt-related transcription factor 2. Here we used recombinant proteins to reconstitute and assess lysine acetylation events catalyzed by Naa10 in vitro. We show that there is no difference in lysine acetylation of substrate proteins with or without Naa10, suggesting that the substrates may be acetylated chemically rather than enzymatically. Together, our data argue against a role for Naa10 in lysine acetylation.

Section: Resultsmentioning

confidence: 73%

The N-terminal Acetyltransferase Naa10/ARD1 Does Not Acetylate Lysine Residues

Magin

March

Marmorstein

2016

“…Acetylation of H3 Lys 14 Impairs Importin Binding-The Importin-binding segments in H3 and H4 tails contain several lysine residues that are acetylated to different degrees in the cytoplasm (H3 Lys 14 , H3 Lys 18 , H4 Lys 5 , and H4 Lys 12 ) (28,30,31,(52)(53)(54). The role of histone acetylation in nuclear import was controversial with reports of both promoting and inhibiting histone import (12,17,31).…”

Section: Discussionmentioning

confidence: 99%

“…However, H3 and H4 import is likely coordinated with upstream and downstream histone processing/nucleosome assembly events and thus may involve other protein players (28,30,31,(52)(53)(54)(55)(56). Furthermore, H3 and H4 dimerize and bind histone chaperone b before binding FIGURE 4.…”

Section: Discussionmentioning

confidence: 99%

Recognition Elements in the Histone H3 and H4 Tails for Seven Different Importins

Soniat

Çağatay

Chook

2016

N-terminal tails of histones H3 and H4 are known to bind several different Importins to import the histones into the cell nucleus. However, it is not known what binding elements in the histone tails are recognized by the individual Importins. Biochemical studies of H3 and H4 tails binding to seven Importins, Imp␤, Kap␤2, Imp4, Imp5, Imp7, Imp9, and Imp␣, show the H3 tail binding more tightly than the H4 tail. The H3 tail binds Kap␤2 and Imp5 with K D values of 77 and 57 nM, respectively, and binds the other five Importins more weakly. Mutagenic analysis shows H3 tail residues 11-27 to be the sole binding segment for Imp␤, Kap␤2, and Imp4. However, Imp5, Imp7, Imp9, and Imp␣ bind two separate elements in the H3 tail: the segment at residues 11-27 and an isoleucine-lysine nuclear localization signal (IK-NLS) motif at residues 35-40. The H4 tail also uses either one or two basic segments to bind the same set of Importins with a similar trend of relative affinities as the H3 tail, albeit at least 10-fold weaker. Of the many lysine residues in the H3 and H4 tails, only acetylation of the H3 Lys 14 substantially decreased binding to several Importins. Lastly, we show that, in addition to the N-terminal tails, the histone fold domains of H3 and H4 and/or the histone chaperone Asf1b are important for Importin-histone recognition.New nucleosomes are assembled in the nucleus during S phase as new core histones H2A, H2B, H3, and H4 are synthesized, assembled into H2A/H2B and H3/H4 dimers in the cytoplasm, and then imported into the nucleus for deposition onto replicating chromatin (1-8). Little is known about cytoplasmic assembly/processing of H2A and H2B, but assembly/processing of H3 and H4 are better understood. In the cytoplasm, H3 and H4 are passed from one histone chaperone to another for folding, assembly into H3/H4 dimers, and acetylation.

“…9). In the Hat1 structure, four of six residues in this region are shown to make interactions with the H4 peptide (Glu-162, Ala-163, Asn-165, and Ile-167) (30). We hypothesize that the same trend may extrapolate to the ␣2-␤7 loop of hMOF such that the hMOF ␣2-␤7 loop might be used for cognate histone H4 peptide recognition in a similar way.…”

Section: Discussionmentioning

confidence: 92%

Structural and Functional Role of Acetyltransferase hMOF K274 Autoacetylation

McCullough

Song

Shin

et al. 2016

Many histone acetyltransferases undergo autoacetylation, either through chemical or enzymatic means, to potentiate enzymatic cognate substrate lysine acetylation, although the mode and molecular role of such autoacetylation is poorly understood. The MYST family of histone acetyltransferases is autoacetylated at an active site lysine residue to facilitate cognate substrate lysine binding and acetylation. Here, we report on a detailed molecular investigation of Lys-274 autoacetylation of the human MYST protein Males Absent on the First (hMOF). A mutational scan of hMOF Lys-274 reveals that all amino acid substitutions of this residue are able to bind cofactor but are significantly destabilized, both in vitro and in cells, and are catalytically inactive for cognate histone H4 peptide lysine acetylation. The x-ray crystal structure of a hMOF K274P mutant suggests that the reduced stability and catalytic activity stems from a disordering of the residue 274-harboring a ␣2-␤7 loop. We also provide structural evidence that a C316S/E350Q mutant, which is defective for cognate substrate lysine acetylation; and biochemical evidence that a K268M mutant, which is defective for Lys-274 chemical acetylation in the context of a K274-peptide, can still undergo quantitative K274 autoacetylation. Together, these studies point to the critical and specific role of hMOF Lys-274 autoacetylation in hMOF stability and cognate substrate acetylation and argues that binding of Ac-CoA to hMOF likely drives Lys-274 autoacetylation for subsequent cognate substrate acetylation.