GO:0033186 CAF-1 complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0033186 (CAF-1 complex) is a conserved heterotrimeric histone chaperone that deposits H3.1-H4 onto newly synthesized DNA during replication and repair.
• The complex is built from p150, p60 and p48 subunits, which together bind acetylated H3/H4 and facilitate nucleosome assembly.
• CAF-1 acts with distinct mechanisms on leading and lagging strands to ensure proper chromatin maturation during S-phase.
• Loss of CAF-1 function triggers cytosolic DNA and dsRNA sensing, linking chromatin assembly to intrinsic immunity in cancer cells.
• CAF-1 couples DNA replication with Hippo pathway target gene expression, connecting chromatin assembly to cell-proliferation control.
• CAF-1 is conserved beyond humans; in Candida albicans it regulates biofilm development through a histone H3 variant.
Description
The CAF-1 complex (chromatin assembly factor 1) is a conserved heterotrimeric histone chaperone that promotes histone H3 and H4 deposition onto newly synthesized DNA during replication or DNA repair, specifically facilitating replication-dependent nucleosome assembly with the major histone H3 (H3.1). In many species the CAF-1 subunits are designated p150, p60 and p48. Because nucleosome assembly must keep pace with the replication fork, CAF-1 is central to preserving chromatin integrity and epigenetic information during cell division. Researchers study CAF-1 to understand how chromatin is rebuilt after DNA synthesis, how replication is coupled to transcription, and how its dysfunction contributes to disease. Beyond replication, CAF-1 has been implicated in DNA repair and in the regulation of gene expression programs, making it a hub for chromatin-based control of genome function. Recent work has also revealed that inhibiting CAF-1 can expose cancer cells to innate immune sensing pathways, suggesting therapeutic opportunities. This article summarizes the QuickGO definition, subunit composition, molecular mechanism, disease links, and the CRISPR-based methods used to study GO:0033186.
CAF-1 complex At A Glance
| GO ID | GO:0033186 |
|---|---|
| GO term | CAF-1 complex |
| Ontology | cellular_component |
| Synonym | chromatin assembly factor 1 complex |
| Major function | Promotes histone H3 and H4 deposition onto newly synthesized DNA during replication or DNA repair; facilitates replication-dependent nucleosome assembly with H3.1 |
| Subunit composition | Heterotrimeric complex; subunits designated p150, p60 and p48 in many species |
| Substrates | Acetylated histones H3/H4; major histone H3 variant H3.1 |
| Conservation | Conserved across eukaryotes, including fungi such as Candida albicans |
| Cellular context | Acts at replication forks and sites of DNA repair to assemble nucleosomes |
What Is GO:0033186?
According to QuickGO, GO:0033186 (CAF-1 complex) is a conserved heterotrimeric protein complex that promotes histone H3 and H4 deposition onto newly synthesized DNA during replication or DNA repair; it specifically facilitates replication-dependent nucleosome assembly with the major histone H3 (H3.1). In many species the CAF-1 subunits are designated p150, p60 and p48. The synonym for this term is chromatin assembly factor 1 complex. In practice, the complex acts as a histone chaperone that binds newly synthesized, acetylated H3/H4 and delivers them to nascent DNA, enabling nucleosome formation behind the replication fork.
Why Is CAF-1 complex Important in Cell Biology?
CAF-1 is essential for maintaining chromatin organization during DNA replication and repair, and its dysfunction has broad consequences for genome stability, gene expression and disease. Because it deposits H3.1-H4 onto newly synthesized DNA, CAF-1 helps propagate epigenetic information through cell division and ensures transcription fidelity during S-phase. Its role in coupling replication with Hippo pathway target gene expression links chromatin assembly to cell-proliferation control. In cancer, inhibition of CAF-1 triggers cytosolic DNA and dsRNA sensing and induces intrinsic immunity in hepatocellular carcinoma, highlighting its therapeutic potential. CAF-1 is also conserved in fungal pathogens, where it regulates biofilm development through a histone H3 variant, underscoring its broad biological relevance.
• Maintains chromatin integrity by depositing H3.1-H4 onto newly synthesized DNA during replication.
• Supports DNA repair-associated nucleosome assembly, contributing to genome stability.
• Ensures transcription fidelity during S-phase by promoting proper chromatin maturation.
• Couples DNA replication with Hippo pathway target gene expression, influencing proliferation.
• Its inhibition induces cytosolic DNA and dsRNA sensing and intrinsic immunity in hepatocellular carcinoma.
• Is conserved in fungal pathogens, where it regulates biofilm development via a histone H3 variant.
• Dysregulation of CAF-1 subunits is linked to homeostasis and disease, including cancer.
• Provides a model for studying how histone chaperones coordinate leading- and lagging-strand synthesis.
• Offers a target for epigenetic and immuno-oncology therapeutic strategies.
• Serves as a paradigm for understanding replication-coupled nucleosome assembly across eukaryotes.
What Happens During CAF-1 complex?
Histone H3/H4 Binding and Delivery
In simple terms: CAF-1 grabs newly made histones and carries them to the DNA.
CAF-1 binds newly synthesized, acetylated histones H3 and H4 and delivers them to sites of DNA synthesis. Structural studies show how the complex engages histone dimers and coordinates their handoff for nucleosome assembly. This binding step is a prerequisite for the subsequent deposition of H3.1-H4 onto nascent DNA.
Replication-Coupled Nucleosome Assembly
In simple terms: As DNA is copied, CAF-1 helps package the new DNA into nucleosomes.
During S-phase, CAF-1 promotes replication-dependent nucleosome assembly with the major histone H3 variant H3.1. It acts at the replication fork to ensure that newly synthesized DNA is rapidly wrapped into nucleosomes. This process is essential for maintaining chromatin structure behind the fork.
Distinct Mechanisms on Leading and Lagging Strands
In simple terms: CAF-1 works differently on the two strands of the replication fork.
CAF-1 deposits newly synthesized histones during DNA replication using distinct mechanisms on the leading and lagging strands. This strand-specific activity helps coordinate nucleosome assembly with the asymmetric architecture of the replication fork. Such coordination is important for efficient chromatin maturation.
Chromatin Maturation and Transcription Fidelity
In simple terms: After deposition, CAF-1 helps the new chromatin mature so genes are read correctly.
Spatiotemporal kinetics of CAF-1-dependent chromatin maturation ensure transcription fidelity during S-phase. CAF-1 activity is temporally coupled to replication to prevent conflicts between transcription and replication. This maturation step contributes to the stable inheritance of chromatin states.
Coupling to DNA Repair and Gene Expression
In simple terms: CAF-1 also helps rebuild chromatin after DNA damage and links to gene control.
CAF-1 promotes histone deposition during DNA repair, contributing to the restoration of chromatin after damage. It also couples Hippo pathway target gene expression and DNA replication, integrating chromatin assembly with proliferative signaling. These functions expand the role of CAF-1 beyond replication alone.
Key Genes Involved in GO:0033186 CAF-1 complex
The CAF-1 complex is composed of conserved subunits and interacts with histones and replication factors; the table below lists the major genes and proteins relevant to GO:0033186.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CHAF1A (p150) | Large subunit of CAF-1; binds histones and coordinates assembly | Frequently studied for its role in chromatin assembly and cancer |
| CHAF1B (p60) | Middle subunit; implicated in homeostasis and disease | Linked to disease processes and studied in knockout models |
| RBBP4 (p48) | Small subunit; histone-binding component | Structural and biochemical studies of CAF-1 |
| H3.1 (H3C1/H3C2 etc.) | Major histone H3 variant deposited by CAF-1 | Key substrate for replication-dependent nucleosome assembly |
| H4 (H4C1 etc.) | Histone H4 deposited with H3.1 | Substrate for CAF-1-mediated nucleosome assembly |
| ASF1 | Histone chaperone that cooperates with CAF-1 | Studied for histone handoff to CAF-1 |
| PCNA | Replication clamp that recruits CAF-1 to forks | Central to replication-coupled assembly |
| MCM2-7 | Replicative helicase; coordinates with CAF-1 at forks | Studied in replication-coupled chromatin assembly |
| YAP/TAZ | Hippo pathway effectors linked to CAF-1 function | Connects CAF-1 to proliferation control |
| H3 variant (Candida) | Clade-specific histone H3 variant regulated by CAF-1 | Studied in fungal biofilm development |
| CAF-1 p150 (fungal) | Subunit required for H3 variant regulation | Model for conserved CAF-1 functions |
| CAF-1 p60 (fungal) | Subunit required for H3 variant regulation | Model for conserved CAF-1 functions |
| CAF-1 p48 (fungal) | Subunit required for H3 variant regulation | Model for conserved CAF-1 functions |
| cGAS-STING components | Pathway activated upon CAF-1 inhibition | Studied in innate immunity of cancer cells |
| dsRNA sensing factors | Pathway activated upon CAF-1 inhibition | Studied in innate immunity of cancer cells |
| Hepatocellular carcinoma markers | Disease context for CAF-1 inhibition | Used to assess intrinsic immunity |
| Histone acetyltransferases | Generate acetylated H3/H4 bound by CAF-1 | Studied in nucleosome assembly |
How Is CAF-1 complex Regulated?
CAF-1 activity is regulated in a cell-cycle-dependent manner, with its function tightly coupled to DNA replication during S-phase. Its recruitment to replication forks is coordinated with replication machinery, and its histone deposition is temporally controlled to ensure chromatin maturation. CAF-1 also interfaces with signaling pathways such as the Hippo pathway, which influences its role in gene expression and proliferation. In fungal systems, CAF-1 regulation is linked to a clade-specific histone H3 variant that controls biofilm development. Additionally, inhibition of CAF-1 activates cytosolic DNA and dsRNA sensing pathways, indicating that its function is monitored by innate immune surveillance.
CAF-1 complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CHAF1A (p150) | Hepatocellular carcinoma; intrinsic immunity | Knockout or knockdown in HCC cell lines |
| CHAF1B (p60) | Homeostasis and disease; cancer | Knockout models to study proliferation and chromatin |
| CAF-1 subunits | Chromatin assembly defects | Point-mutation models to dissect subunit function |
| CAF-1 complex | Fungal biofilm development | Candida albicans knockout strains |
| CAF-1 complex | Transcription fidelity during S-phase | Tagged knock-in for live-cell imaging |
CAF-1 in Cancer and Intrinsic Immunity
Inhibition of the CAF-1 histone chaperone complex triggers cytosolic DNA and dsRNA sensing pathways and induces intrinsic immunity of hepatocellular carcinoma. This suggests that CAF-1 dysfunction can expose cancer cells to innate immune detection, providing a rationale for therapeutic targeting. CAF-1 subunits have also been linked to homeostasis and disease, including cancer.
CAF-1 and Chromatin-Related Disorders
The role of the chromatin assembly complex and its p60 subunit (CHAF1b) in homeostasis and disease has been reviewed, highlighting its importance in maintaining normal cellular function. Disruption of CAF-1-dependent chromatin assembly can affect genome stability and gene expression, contributing to disease phenotypes.
CAF-1 in Fungal Pathogenesis
In Candida albicans, negative regulation of biofilm development by the CUG-Ser1 clade-specific histone H3 variant depends on the canonical histone chaperone CAF-1 complex. This links CAF-1 to fungal virulence traits and suggests it may be relevant to antifungal strategies.
From CAF-1 complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of CAF-1 induce innate immune sensing? | CHAF1A/CHAF1B knockout in cancer cell lines |
| How does p60 contribute to homeostasis and disease? | CHAF1B knockout mouse or cell model |
| What is the strand-specific role of CAF-1 at forks? | Point mutations in CAF-1 subunits combined with replication assays |
| How does CAF-1 couple to Hippo signaling? | Knockout or knockdown with Hippo target gene readouts |
| What is the structural basis of histone binding? | Recombinant CAF-1 complexes with tagged subunits |
| How does CAF-1 ensure transcription fidelity? | Tagged knock-in for spatiotemporal imaging |
How to Study the CAF-1 complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Chromatin assembly assay | Nucleosome formation on newly synthesized DNA | Studying CAF-1 histone deposition |
| Structural biology (cryo-EM/X-ray) | Histone binding and complex architecture | Understanding CAF-1 mechanism |
| Replication fork assays | Leading vs lagging strand histone deposition | Dissecting strand-specific CAF-1 functions |
| Genome-wide profiling | Chromatin maturation and transcription fidelity | S-phase chromatin dynamics |
| Innate immune sensing assays | Cytosolic DNA/dsRNA pathway activation | Evaluating CAF-1 inhibition in cancer |
| Knockout/knockdown models | Loss-of-function phenotypes | Studying homeostasis and disease |
| Hippo pathway reporter assays | Target gene expression and replication coupling | Linking CAF-1 to proliferation |
| Fungal biofilm assays | Biofilm development and H3 variant regulation | Studying CAF-1 in Candida albicans |
Biochemical and Structural Approaches
Purification of recombinant CAF-1 complexes and structural studies have provided insights into histone binding and nucleosome assembly. These methods reveal how the heterotrimeric complex engages H3/H4 and coordinates deposition.
Replication and Chromatin Assays
Replication-coupled nucleosome assembly can be studied using in vitro replication systems and chromatin assembly assays. Such assays have been used to define the distinct mechanisms of CAF-1 on leading and lagging strands.
Genome-Wide and Kinetic Profiling
Spatiotemporal kinetics of CAF-1-dependent chromatin maturation can be monitored using genome-wide approaches to assess transcription fidelity during S-phase. These methods help link CAF-1 activity to chromatin state and gene expression.
Disease and Immunity Models
Inhibition of CAF-1 in hepatocellular carcinoma models can be combined with cytosolic DNA and dsRNA sensing readouts to study intrinsic immunity. Such models are useful for evaluating CAF-1 as a therapeutic target.
How CRISPR Can Be Used to Study GO:0033186 CAF-1 complex
Knockout
CRISPR knockout of CHAF1A or CHAF1B can be used to study loss of CAF-1 function, including effects on chromatin assembly, proliferation, and innate immune activation. Such models help determine whether CAF-1 is required for specific cellular processes.
Point Mutation
Point mutations in CAF-1 subunits can dissect domain-specific functions, such as histone binding or strand-specific deposition. These models are valuable for separating distinct activities of the complex.
Knock-in
Tagged knock-in of CAF-1 subunits enables live-cell imaging and spatiotemporal tracking of chromatin maturation during S-phase. This approach helps visualize how CAF-1 coordinates with replication.
Overexpression
Overexpression of CAF-1 subunits can be used to test gain-of-function effects on chromatin assembly and gene expression. Such models may reveal how excess CAF-1 influences proliferation and Hippo pathway target genes.
How EDITGENE Supports CAF-1 complex Research
Researchers studying CAF-1 complex-related genes often need to determine whether a candidate gene is causally involved in chromatin assembly, replication-coupled processes, or disease phenotypes. CRISPR-based models provide a precise way to test these hypotheses by introducing targeted knockouts, point mutations, knock-ins, or overexpression constructs in relevant cell systems.
Contact EDITGENE today to design your custom CRISPR model for CAF-1 complex research.
Frequently Asked Questions About CAF-1 complex
What is the CAF-1 complex?
The CAF-1 complex (GO:0033186) is a conserved heterotrimeric histone chaperone that promotes histone H3 and H4 deposition onto newly synthesized DNA during replication or DNA repair, facilitating replication-dependent nucleosome assembly with H3.1.
What genes are involved in the CAF-1 complex?
The major genes include CHAF1A (p150), CHAF1B (p60), and RBBP4 (p48), which encode the subunits of the heterotrimeric complex.
What is the function of CAF-1 in DNA replication?
CAF-1 deposits newly synthesized histones during DNA replication using distinct mechanisms on the leading and lagging strands, ensuring proper chromatin assembly.
How is CAF-1 linked to cancer?
Inhibition of CAF-1 triggers cytosolic DNA and dsRNA sensing pathways and induces intrinsic immunity in hepatocellular carcinoma, suggesting a therapeutic opportunity.
What are the subunits of CAF-1?
In many species the CAF-1 subunits are designated p150, p60, and p48, forming a conserved heterotrimeric complex.
Does CAF-1 play a role in DNA repair?
Yes, CAF-1 promotes histone H3 and H4 deposition onto newly synthesized DNA during DNA repair, contributing to chromatin restoration.
How does CAF-1 ensure transcription fidelity?
CAF-1-dependent chromatin maturation follows spatiotemporal kinetics that ensure transcription fidelity during S-phase.
Is CAF-1 conserved in fungi?
Yes, in Candida albicans the canonical histone chaperone CAF-1 complex regulates biofilm development through a clade-specific histone H3 variant.
What methods are used to study CAF-1?
Common methods include chromatin assembly assays, structural biology, replication fork assays, genome-wide profiling, and CRISPR-based knockout or knock-in models.
How can CRISPR be used to study CAF-1?
CRISPR knockout, point mutation, knock-in, and overexpression models allow researchers to dissect CAF-1 subunit functions and their roles in disease and immunity.
Conclusion
The CAF-1 complex (GO:0033186) is a conserved heterotrimeric histone chaperone essential for depositing H3.1-H4 onto newly synthesized DNA during replication and repair. Its strand-specific mechanisms and role in chromatin maturation ensure transcription fidelity and genome stability. Beyond replication, CAF-1 couples to Hippo signaling and, when inhibited, can trigger innate immune sensing in cancer cells. Studying CAF-1 with CRISPR-based models offers a powerful approach to understand its contributions to health and disease.
References
- 1. Chan FF et al.. 2024. Inhibition of CAF-1 histone chaperone complex triggers cytosolic DNA and dsRNA sensing pathways and induces intrinsic immunity of hepatocellular carcinoma.. Hepatology 80(2):295-311 PMID: 38051950
- 2. Volk A et al.. 2015. The role of the chromatin assembly complex (CAF-1) and its p60 subunit (CHAF1b) in homeostasis and disease.. Biochim Biophys Acta 1849(8):979-86 PMID: 26066981
- 3. Rouillon C et al.. 2023. CAF-1 deposits newly synthesized histones during DNA replication using distinct mechanisms on the leading and lagging strands.. Nucleic Acids Res 51(8):3770-3792 PMID: 36942484
- 4. Yee WB et al.. 2019. The CAF-1 complex couples Hippo pathway target gene expression and DNA replication.. Mol Biol Cell 30(23):2929-2942 PMID: 31553691
- 5. Verreault A et al.. 1996. Nucleosome assembly by a complex of CAF-1 and acetylated histones H3/H4.. Cell 87(1):95-104 PMID: 8858152
- 6. Singha R et al.. 2023. Negative regulation of biofilm development by the CUG-Ser1 clade-specific histone H3 variant is dependent on the canonical histone chaperone CAF-1 complex in Candida albicans.. Mol Microbiol 119(5):574-585 PMID: 36855815
- 7. Liu CP et al.. 2023. Structural insights into histone binding and nucleosome assembly by chromatin assembly factor-1.. Science 381(6660):eadd8673 PMID: 37616371
- 8. Chen B et al.. 2023. Spatiotemporal kinetics of CAF-1-dependent chromatin maturation ensures transcription fidelity during S-phase.. Genome Res 33(12):2108-2118 PMID: 38081658
