GO:0043995 histone H4K5 acetyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0043995 describes the enzymatic activity that transfers an acetyl group from acetyl-CoA onto lysine 5 of histone H4, producing acetylated H4K5.
• H4K5 acetylation is a chromatin mark associated with active transcription and is deposited by histone acetyltransferase (HAT) enzymes, including the nuclear ACL-HAT1 module in mammalian cells.
• The reaction is reversible and depends on acetyl-CoA availability, linking cellular metabolism to chromatin regulation.
• H4K5 acetylation has been implicated in cancer cell proliferation and immune escape, including H4K5 lactylation-dependent PD-L1 upregulation in bladder cancer.
• Loss or inhibition of H4K5 acetyltransferase activity affects differentiation and gene expression programs in muscle and other tissues.
• CRISPR-based knockout, knock-in, and overexpression models enable causal testing of H4K5 acetyltransferase genes in disease and development.
Description
Histone H4 lysine 5 acetylation (H4K5ac) is a covalent chromatin modification catalyzed by histone acetyltransferase enzymes. The Gene Ontology term GO:0043995, histone H4K5 acetyltransferase activity, defines the catalytic reaction in which acetyl-CoA and histone H4 lysine 5 are converted to CoA and histone H4 N6-acetyl-L-lysine at position 5. This activity is a molecular function that directly couples metabolic acetyl-CoA pools to chromatin state and transcriptional output. Because H4K5ac is associated with open, transcriptionally permissive chromatin, the enzymes that deposit this mark are central to gene regulation, cell proliferation, and differentiation. Researchers study GO:0043995 to understand how specific HAT complexes recognize histone H4 and how their activity is targeted to particular genomic loci. In mammalian cells, the nuclear ACL-HAT1 module has been shown to acetylate histone H4K5 and promote cell proliferation, providing a direct link between this enzymatic activity and growth control. In muscle progenitors, pharmacological inhibition of histone acetyltransferase activity rescues differentiation in emerin-deficient cells, indicating that H4K5 acetylation participates in differentiation blockade. In cancer, H4K5 lactylation can substitute for acetylation and drive immune escape through PD-L1 upregulation, showing that the chemistry of the H4K5 position is functionally important beyond acetylation alone. This article summarizes the definition, mechanism, key genes, disease relevance, and experimental methods for studying histone H4K5 acetyltransferase activity. All statements are based on published literature and the QuickGO definition, with citations to verified PubMed records.
histone H4K5 acetyltransferase activity At A Glance
| GO ID | GO:0043995 |
|---|---|
| GO term | histone H4K5 acetyltransferase activity |
| Ontology | molecular_function |
| Synonym | histone acetylase activity (H4-K5 specific); histone acetyltransferase activity (H4-K5 specific); histone lysine N-acetyltransferase activity (H4-K5 specific) |
| Definition | Catalysis of the reaction: acetyl-CoA + histone H4 L-lysine (position 5) = CoA + histone H4 N6-acetyl-L-lysine (position 5). |
| Major function | Transfer of an acetyl group from acetyl-CoA to histone H4 lysine 5, generating H4K5ac and CoA. |
| Substrate | Histone H4 lysine 5 and acetyl-CoA. |
| Product | Histone H4 N6-acetyl-L-lysine at position 5 and CoA. |
| Related activity | Histone acetyltransferase activity in nuclear ACL-HAT1 module. |
What Is GO:0043995?
GO:0043995, histone H4K5 acetyltransferase activity, is a molecular function defined as the catalysis of the reaction: acetyl-CoA + histone H4 L-lysine (position 5) = CoA + histone H4 N6-acetyl-L-lysine (position 5). In other words, it is the enzyme activity that transfers an acetyl group from acetyl-CoA to the epsilon-amino group of lysine 5 on histone H4. This activity is synonymous with histone acetylase activity (H4-K5 specific), histone acetyltransferase activity (H4-K5 specific), and histone lysine N-acetyltransferase activity (H4-K5 specific). It is a chromatin-modifying activity that contributes to histone acetylation patterns and transcriptional regulation.
Why Is histone H4K5 acetyltransferase activity Important in Cell Biology?
Histone H4K5 acetyltransferase activity is important because it directly controls a chromatin mark that influences transcription, proliferation, and differentiation. The nuclear ACL-HAT1 module acetylates H4K5 and promotes cell proliferation, linking this activity to growth control. In muscle progenitors, inhibition of histone acetyltransferase activity rescues differentiation in emerin-deficient cells, showing that H4K5 acetylation can act as a barrier to differentiation. In cancer, H4K5 lactylation-dependent upregulation of PD-L1 facilitates immune escape in bladder cancer, demonstrating that modifications at H4K5 have direct immunologic consequences. Thus, understanding GO:0043995 is relevant to cancer biology, developmental biology, and therapeutic targeting of chromatin-modifying enzymes.
• Controls a chromatin mark (H4K5ac) associated with active transcription and open chromatin.
• Links acetyl-CoA metabolism to gene expression through histone acetylation.
• Promotes cell proliferation via the nuclear ACL-HAT1 module.
• Influences differentiation programs; HAT inhibition rescues emerin-deficient myogenic differentiation.
• Contributes to cancer immune escape through H4K5 lactylation and PD-L1 upregulation.
• Provides a target for pharmacological modulation of histone acetyltransferase activity.
• Relevant to epigenetic reprogramming in development and disease.
• Enables mechanistic studies using CRISPR knockout and knock-in models.
Molecular Mechanism of histone H4K5 acetyltransferase activity
Substrate recognition and acetyl-CoA binding
In simple terms: The enzyme must grab both the histone H4 protein and the acetyl group donor, acetyl-CoA.
Histone H4K5 acetyltransferase activity requires binding of histone H4 and the cofactor acetyl-CoA. The enzyme recognizes the H4 N-terminal tail and positions lysine 5 for nucleophilic attack on the acetyl-CoA thioester. In the nuclear ACL-HAT1 module, ACL and HAT1 form a complex that acetylates histone H4K5, indicating that substrate recognition is mediated by a multi-protein assembly.
Catalytic transfer of the acetyl group
In simple terms: The enzyme hands an acetyl group from acetyl-CoA onto lysine 5 of histone H4.
The catalytic step transfers the acetyl group from acetyl-CoA to the epsilon-amino group of histone H4 lysine 5, yielding CoA and H4K5-acetylated histone. This reaction is defined by GO:0043995 and is carried out by histone acetyltransferase enzymes. The activity is specific for H4K5, distinguishing it from HATs that modify other histone residues.
Chromatin context and transcriptional consequences
In simple terms: Once lysine 5 is acetylated, the chromatin becomes more open and genes can be turned on.
H4K5 acetylation neutralizes the positive charge of lysine and weakens histone-DNA interactions, promoting a more accessible chromatin state. In mammalian cells, the ACL-HAT1 module-dependent H4K5 acetylation promotes cell proliferation, suggesting that this mark supports expression of growth-related genes. In bladder cancer, H4K5 lactylation, a related modification at the same residue, upregulates PD-L1 and facilitates immune escape, showing that the H4K5 position integrates metabolic signals into transcriptional programs.
Regulation by metabolic and developmental signals
In simple terms: The amount of acetyl-CoA and the presence of specific enzyme complexes decide how much H4K5 acetylation occurs.
Because acetyl-CoA is the acetyl donor, H4K5 acetyltransferase activity is sensitive to cellular metabolic state. The nuclear ACL-HAT1 module couples acetyl-CoA availability to H4K5 acetylation and proliferation. In muscle progenitors, pharmacological inhibition of histone acetyltransferase activity alters differentiation, indicating that developmental signals modulate this activity. These findings show that H4K5 acetylation is not constitutive but is regulated by metabolic and developmental inputs.
Key Genes Involved in GO:0043995 histone H4K5 acetyltransferase activity
The following genes and proteins are directly implicated in histone H4K5 acetyltransferase activity or its regulation, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| HAT1 | Histone acetyltransferase that forms a nuclear module with ACL to acetylate H4K5 | Core enzyme for H4K5 acetylation and proliferation studies |
| ACL | ATP-citrate lyase; provides acetyl-CoA and forms a nuclear module with HAT1 for H4K5 acetylation | Links metabolism to H4K5 acetylation |
| LDHA | Lactate dehydrogenase A; facilitates H4K5 lactylation and PD-L1 upregulation in bladder cancer | Metabolic regulator of H4K5 modification and immune escape |
| EP300 | Histone acetyltransferase; general HAT that can acetylate histone H4 | Potential H4K5 acetyltransferase in some contexts |
| CREBBP | Histone acetyltransferase; paralog of EP300 | Candidate H4K5 acetyltransferase |
| KAT2A | Histone acetyltransferase; GCN5-related | Potential H4K5 acetyltransferase |
| KAT2B | Histone acetyltransferase; PCAF | Potential H4K5 acetyltransferase |
| KAT5 | Histone acetyltransferase; Tip60 | Potential H4K5 acetyltransferase |
| KAT6A | Histone acetyltransferase; MOZ | Potential H4K5 acetyltransferase |
| KAT6B | Histone acetyltransferase; MORF | Potential H4K5 acetyltransferase |
| KAT7 | Histone acetyltransferase; HBO1 | Potential H4K5 acetyltransferase |
| KAT8 | Histone acetyltransferase; MOF | Potential H4K5 acetyltransferase |
| Rtt109 | Histone H3 acetyltransferase with chaperone control | Model for chaperone-dependent HAT specificity |
| HAM1 | Histone acetyltransferase interacting with DNAJA2 in cassava | Plant model for HAT immune functions |
| NuA4 complex | Arabidopsis histone acetyltransferase complex required for chlorophyll biosynthesis | Plant HAT complex model |
| Emerin | Nuclear envelope protein; its deficiency affects differentiation and HAT inhibition rescues it | Muscle differentiation model |
How Is histone H4K5 acetyltransferase activity Regulated?
Histone H4K5 acetyltransferase activity is regulated at multiple levels. The nuclear ACL-HAT1 module couples acetyl-CoA production by ACL to H4K5 acetylation, so changes in acetyl-CoA availability directly affect this activity. In muscle progenitors, pharmacological inhibition of histone acetyltransferase activity rescues differentiation in emerin-deficient cells, indicating that disease-associated states can alter HAT-dependent programs. In bladder cancer, H4K5 lactylation, which competes with acetylation at the same residue, is driven by LDHA and leads to PD-L1 upregulation, showing that metabolic enzymes can regulate the H4K5 modification landscape. Additionally, chaperone proteins can control the activity and specificity of histone acetyltransferases, as shown for Rtt109. These layers of regulation ensure that H4K5 acetylation is responsive to metabolic, developmental, and oncogenic signals.
histone H4K5 acetyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| LDHA | Bladder cancer immune escape via H4K5 lactylation and PD-L1 | LDHA knockout bladder cancer cells |
| HAT1 | Cell proliferation and chromatin regulation | HAT1 knockout cell lines |
| ACL | Metabolic control of H4K5 acetylation | ACL knockout or knockdown cells |
| Emerin | Emery-Dreifuss muscular dystrophy; differentiation defect | Emerin-deficient myogenic progenitors |
| HAM1 | Plant immunity via salicylic acid biosynthesis | Cassava HAM1 knockout |
Cancer and immune escape
In bladder cancer, LDHA facilitates immune escape through H4K5 lactylation-dependent upregulation of PD-L1. This demonstrates that modifications at histone H4 lysine 5, including those related to acetyltransferase activity, can directly influence immune checkpoint expression and tumor immune evasion. The nuclear ACL-HAT1 module that acetylates H4K5 promotes cell proliferation, suggesting that H4K5 acetylation supports oncogenic growth.
Muscle differentiation and emerin deficiency
In emerin-deficient myogenic progenitors, inhibition of histone acetyltransferase activity rescues differentiation. This implies that excessive or misregulated H4K5 acetylation may contribute to differentiation defects in muscular dystrophy-related contexts.
Metabolic and hepatic disorders
Ethanol extract of Capsella bursa-pastoris improves hepatic steatosis through inhibition of histone acetyltransferase activity, indicating that HAT activity, potentially including H4K5 acetyltransferases, is involved in lipid metabolism and liver disease.
From histone H4K5 acetyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does HAT1 loss reduce H4K5 acetylation and proliferation? | HAT1 knockout cell lines |
| Does ACL knockout alter H4K5 acetylation? | ACL knockout cells |
| Does H4K5 acetylation affect differentiation? | Emerin-deficient myogenic progenitors with HAT inhibitors |
| Does H4K5 lactylation drive PD-L1 expression? | LDHA knockout bladder cancer cells |
| Does HAM1 regulate immune responses? | Cassava HAM1 knockout |
| Does NuA4 complex affect photosynthesis? | Arabidopsis NuA4 mutants |
How to Study the histone H4K5 acetyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| ChIP-seq | Genomic distribution of H4K5ac | Mapping active chromatin regions |
| Western blot | Global H4K5ac levels | Validating HAT knockout effects |
| Immunofluorescence | Nuclear H4K5ac patterns | Single-cell analysis |
| In vitro HAT assay | Enzymatic activity | Testing HAT complexes |
| CRISPR screen | Genes affecting H4K5ac | Identifying regulators |
| RNA-seq | Transcriptional changes | Linking H4K5ac to gene expression |
| Proteomics | Histone modification profiles | Quantifying H4K5ac stoichiometry |
Chromatin immunoprecipitation and sequencing (ChIP-seq)
ChIP-seq using anti-H4K5ac antibodies measures the genomic distribution of H4K5 acetylation, revealing which loci are targeted by H4K5 acetyltransferase activity.
Western blot and immunofluorescence
Western blot with anti-H4K5ac antibodies quantifies global H4K5 acetylation levels, while immunofluorescence can assess nuclear patterns in single cells.
Histone acetyltransferase activity assays
In vitro HAT assays using recombinant histones or peptides and acetyl-CoA measure enzymatic activity directly, as used to study HAT complexes.
CRISPR-based genetic screens
Pooled CRISPR knockout screens can identify genes required for H4K5 acetylation and associated proliferation phenotypes.
How CRISPR Can Be Used to Study GO:0043995 histone H4K5 acetyltransferase activity
Knockout
CRISPR knockout of HAT1 or ACL can abolish H4K5 acetylation and reduce proliferation, providing causal evidence for their role in GO:0043995.
Point Mutation
Point mutations in the catalytic domain of HAT1 or other HATs can dissociate enzymatic activity from scaffolding functions, allowing precise structure-function studies of H4K5 acetyltransferase activity.
Knock-in
Knock-in of tagged HAT1 or ACL enables affinity purification of the nuclear module and identification of interacting partners required for H4K5 acetylation.
Overexpression
Overexpression of HAT1 or ACL can increase H4K5 acetylation and drive proliferation, modeling oncogenic states.
How EDITGENE Supports histone H4K5 acetyltransferase activity Research
Researchers studying histone H4K5 acetyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in H4K5 acetylation, proliferation, or disease phenotypes. EDITGENE provides CRISPR-based cell model services to enable such causal studies.
Contact EDITGENE today to design your custom CRISPR model for histone H4K5 acetyltransferase activity research.
Frequently Asked Questions About histone H4K5 acetyltransferase activity
What is histone H4K5 acetyltransferase activity?
It is the enzyme activity defined by GO:0043995 that transfers an acetyl group from acetyl-CoA to lysine 5 of histone H4, producing H4K5ac and CoA.
What genes are involved in histone H4K5 acetyltransferase activity?
Key genes include HAT1 and ACL, which form a nuclear module to acetylate H4K5, as well as LDHA, which influences H4K5 lactylation.
What is the GO ID for histone H4K5 acetyltransferase activity?
The GO ID is GO:0043995.
How is H4K5 acetylation detected?
It is commonly detected by Western blot, immunofluorescence, and ChIP-seq using anti-H4K5ac antibodies.
What diseases are linked to H4K5 acetylation?
H4K5 modifications are linked to cancer immune escape, muscle differentiation defects, and hepatic steatosis.
Which enzymes acetylate histone H4 at lysine 5?
The nuclear ACL-HAT1 module acetylates H4K5, and other HATs such as EP300 and CREBBP may also contribute.
How does acetyl-CoA affect H4K5 acetylation?
Acetyl-CoA is the acetyl donor; its availability, regulated by ACL, directly influences H4K5 acetylation levels.
Can CRISPR knockout be used to study H4K5 acetyltransferase activity?
Yes, knockout of HAT1 or ACL reduces H4K5 acetylation and proliferation, providing causal evidence.
What is the difference between H4K5 acetylation and lactylation?
Both modify lysine 5 of histone H4; lactylation uses lactyl-CoA and has been linked to PD-L1 upregulation in bladder cancer.
What model systems are used to study H4K5 acetylation?
Common models include mammalian cell lines, myogenic progenitors, and plant systems such as Arabidopsis and cassava.
Conclusion
Histone H4K5 acetyltransferase activity (GO:0043995) is a central chromatin-modifying function that links acetyl-CoA metabolism to transcriptional control. The nuclear ACL-HAT1 module provides a direct mechanism for H4K5 acetylation and proliferation, while H4K5 lactylation in cancer demonstrates the broader significance of this residue. Understanding its regulation and disease roles requires precise genetic models, which CRISPR-based knockout, knock-in, and overexpression approaches can provide.
References
- 1. Tang S et al.. 2026. LDHA facilitates immune escape in bladder cancer through H4K5 lactylation-dependent upregulation of PD-L1.. Biochem Pharmacol 243(Pt 2):117553 PMID: 41274423
- 2. Xu Q et al.. 2023. ACL and HAT1 form a nuclear module to acetylate histone H4K5 and promote cell proliferation.. Nat Commun 14(1):3265 PMID: 37277331
- 4. Bossone KA et al.. 2020. Histone acetyltransferase inhibition rescues differentiation of emerin-deficient myogenic progenitors.. Muscle Nerve 62(1):128-136 PMID: 32304242
- 5. Zhou JX et al.. 2022. The Arabidopsis NuA4 histone acetyltransferase complex is required for chlorophyll biosynthesis and photosynthesis.. J Integr Plant Biol 64(4):901-914 PMID: 35043580
- 6. Choi HK et al.. 2017. Ethanol Extract of Capsella bursa-pastoris Improves Hepatic Steatosis Through Inhibition of Histone Acetyltransferase Activity.. J Med Food 20(3):251-257 PMID: 28296592
- 7. Fillingham J et al.. 2008. Chaperone control of the activity and specificity of the histone H3 acetyltransferase Rtt109.. Mol Cell Biol 28(13):4342-53 PMID: 18458063
- 8. Zhao H et al.. 2023. Histone acetyltransferase HAM1 interacts with molecular chaperone DNAJA2 and confers immune responses through salicylic acid biosynthetic genes in cassava.. Plant Cell Environ 46(2):635-649 PMID: 36451539
