GO:0004312 fatty acid synthase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004312 fatty acid synthase activity catalyzes the NADPH-dependent synthesis of long-chain fatty acids from acetyl-CoA and malonyl-CoA.
• FASN is a multifunctional enzyme that integrates seven catalytic activities into a single polypeptide or complex, often called a chemical nanofactory.
• FASN is overexpressed in many cancers and supports the lipogenic phenotype required for tumor growth and metastasis.
• FASN activity is regulated by post-translational modifications, including lactylation, which can inhibit lipid synthesis.
• Loss of FBXW7β enhances FASN-mediated lipogenesis and promotes colorectal cancer growth, linking FASN to oncogenic signaling.
• FASN-mediated lipid droplet formation enhances macrophage killing of Staphylococcus aureus, highlighting a role in host defense.
Description
Fatty acid synthase (FASN) is the central enzyme responsible for de novo synthesis of long-chain fatty acids in many organisms. The Gene Ontology term GO:0004312, fatty acid synthase activity, captures the catalytic function that converts acetyl-CoA and malonyl-CoA into long-chain fatty acids using NADPH as a reducing agent. This activity is essential for cellular membrane biogenesis, energy storage, and signaling, and it is frequently upregulated in cancer and other proliferative diseases. Understanding FASN at the molecular level is critical for developing targeted therapies and for interpreting metabolic reprogramming in disease. The enzyme is a large multifunctional protein or complex that performs multiple sequential reactions, making it a fascinating subject for structural and mechanistic studies. In this article, we provide a comprehensive overview of GO:0004312, covering its definition, mechanism, key genes, disease relevance, and research methods, with a focus on how CRISPR-based models can accelerate discovery.
fatty acid synthase activity At A Glance
| GO ID | GO:0004312 |
|---|---|
| GO term | fatty acid synthase activity |
| Ontology | molecular_function |
| Synonym | acyl-CoA:malonyl-CoA C-acyltransferase (decarboxylating, oxoacyl- and enoyl-reducing and thioester-hydrolysing); fatty-acid synthase activity |
| Definition | Catalysis of the reaction: acetyl-CoA + n malonyl-CoA + 2n NADPH + 2n H+ = long-chain fatty acid + n+1 CoA + n CO2 + 2n NADP+. |
| Major function | De novo synthesis of long-chain fatty acids from acetyl-CoA and malonyl-CoA using NADPH. |
| EC number | 2.3.1.85 |
| Related genes | FASN (human), Fasn (mouse), and homologs in other species. |
What Is GO:0004312?
GO:0004312 fatty acid synthase activity is defined as the catalysis of the reaction: acetyl-CoA + n malonyl-CoA + 2n NADPH + 2n H+ = long-chain fatty acid + n+1 CoA + n CO2 + 2n NADP+. In simpler terms, it is the enzymatic activity that builds long-chain fatty acids by repeatedly adding two-carbon units from malonyl-CoA to a growing acyl chain, while consuming NADPH and releasing CO2.
Why Is fatty acid synthase activity Important in Cell Biology?
Fatty acid synthase activity is fundamental to cellular metabolism, providing fatty acids for membrane synthesis, energy storage, and lipid signaling. Its dysregulation is a hallmark of many cancers, where elevated FASN supports rapid proliferation and survival. Beyond cancer, FASN plays roles in immune cell function, as shown by its involvement in macrophage killing of Staphylococcus aureus. The enzyme is also a target for therapeutic intervention, with numerous inhibitors in development. Therefore, understanding GO:0004312 is crucial for both basic biology and translational research.
• FASN is overexpressed in many cancers, including breast, prostate, and colorectal cancer, and correlates with poor prognosis.
• Inhibition of FASN reduces tumor growth and metastasis in preclinical models, making it a promising drug target.
• FASN supports brain metastasis in breast cancer, highlighting its role in advanced disease.
• Loss of FBXW7β enhances FASN-mediated lipogenesis and promotes colorectal cancer growth.
• FASN-mediated lipid droplet formation is important for macrophage defense against Staphylococcus aureus.
• FASN activity is regulated by lactylation, linking metabolic state to enzyme function.
• The enzyme is a model system for understanding multifunctional enzyme complexes and substrate channeling.
• FASN is involved in lipid synthesis in various tissues, impacting obesity and metabolic disorders.
• Targeting FASN may overcome drug resistance in cancer cells that rely on lipogenesis.
• FASN expression is regulated by oncogenic pathways such as PI3K/AKT and mTOR, connecting growth signaling to metabolism.
Core Mechanisms of fatty acid synthase activity
Initiation and Loading of Acetyl-CoA
In simple terms: The enzyme starts by loading an acetyl group onto its acyl carrier protein.
The first step in fatty acid synthesis involves the transfer of an acetyl group from acetyl-CoA to the acyl carrier protein (ACP) domain of FASN, catalyzed by the malonyl/acetyltransferase (MAT) domain. This priming reaction is essential for the subsequent elongation cycles. In the animal FASN, the acetyl group is initially loaded onto the ACP and then transferred to the ketoacyl synthase (KS) domain, which serves as the starting point for chain elongation.
Elongation Cycle: Condensation, Reduction, Dehydration, and Reduction
In simple terms: The enzyme repeatedly adds two-carbon units to the growing fatty acid chain through four steps.
Each elongation cycle begins with the condensation of a malonyl group (decarboxylated) with the growing acyl chain, catalyzed by the KS domain. The resulting β-ketoacyl intermediate is then reduced by the ketoacyl reductase (KR) domain using NADPH, dehydrated by the dehydratase (DH) domain, and further reduced by the enoyl reductase (ER) domain using NADPH to form a saturated acyl chain. This cycle repeats seven times to produce palmitate (C16:0) in most organisms.
Termination and Release of Fatty Acid
In simple terms: The finished fatty acid chain is cut off from the enzyme.
Once the acyl chain reaches the desired length, typically 16 carbons, the thioesterase (TE) domain hydrolyzes the thioester bond to release the free fatty acid. This termination step is critical for product specificity and is regulated to ensure proper chain length. In some FASN systems, the TE domain also participates in proofreading and release of incomplete chains.
Structural Organization of FASN
In simple terms: FASN is a large enzyme with multiple active sites arranged in a specific order.
Animal FASN is a homodimer where each monomer contains all seven catalytic domains arranged as a linear sequence of alternating catalytic and structural domains. The domains are connected by flexible linkers that allow the ACP to shuttle intermediates between active sites. This architecture enables efficient substrate channeling and processive catalysis. In contrast, bacterial and plant FASN systems consist of separate monofunctional proteins that assemble into a complex.
Cofactor Requirements and Redox Balance
In simple terms: The enzyme needs NADPH to provide reducing power.
FASN requires NADPH as a cofactor for the two reduction steps in each elongation cycle. NADPH is oxidized to NADP+ during the reduction of the β-ketoacyl and enoyl intermediates. The enzyme's activity is therefore tightly linked to cellular NADPH supply, which is generated by the pentose phosphate pathway and malic enzyme. This redox dependency makes FASN sensitive to the cellular metabolic state.
Regulation of FASN Activity
In simple terms: The enzyme's activity can be turned up or down by modifications and signaling pathways.
FASN activity is regulated at multiple levels, including transcriptional control by sterol regulatory element-binding proteins (SREBPs) and post-translational modifications. For example, lactylation of FASN inhibits its lipid synthesis activity, linking lactate metabolism to fatty acid production. Additionally, FBXW7β loss-of-function enhances FASN-mediated lipogenesis, indicating that ubiquitin-proteasome pathways can modulate FASN stability or activity. These regulatory mechanisms allow cells to adapt fatty acid synthesis to changing metabolic demands.
Key Genes Involved in GO:0004312 fatty acid synthase activity
The following genes and proteins are directly involved in or regulate fatty acid synthase activity (GO:0004312).
| Gene | Major Role | Research Relevance |
|---|---|---|
| FASN | Encodes the multifunctional fatty acid synthase enzyme in humans. | Central to de novo lipogenesis; overexpressed in cancers; target for inhibitors. |
| Fasn | Mouse homolog of FASN. | Used in knockout and transgenic models to study metabolism and cancer. |
| FBXW7 | Encodes an F-box protein that targets proteins for degradation; FBXW7β loss enhances FASN-mediated lipogenesis. | Tumor suppressor; its loss promotes colorectal cancer growth via FASN. |
| SREBF1 | Encodes SREBP-1, a transcription factor that activates FASN expression. | Master regulator of lipogenesis; links growth signaling to FASN. |
| MLXIPL | Encodes ChREBP, a transcription factor that regulates FASN in response to glucose. | Mediates carbohydrate-induced lipogenesis. |
| ACACA | Encodes acetyl-CoA carboxylase, which produces malonyl-CoA for FASN. | Provides substrate for FASN; coordinated regulation. |
| ACSL1 | Encodes acyl-CoA synthetase, which activates fatty acids for further metabolism. | Supplies acetyl-CoA for FASN; involved in lipid remodeling. |
| NADPH oxidases | Enzymes that generate NADPH, indirectly supporting FASN activity. | Redox balance affects FASN function. |
| LDHA | Lactate dehydrogenase A, involved in lactate production and lactylation of FASN. | Links glycolysis to FASN regulation via lactylation. |
| SIRT1 | Deacetylase that may regulate FASN acetylation status. | Potential regulator of FASN activity through deacetylation. |
| AMPK | Energy sensor kinase that inhibits lipogenesis, including FASN. | Links energy status to FASN regulation. |
| mTOR | Kinase that promotes lipogenesis via SREBP activation. | Growth signaling upstream of FASN. |
| PPARG | Nuclear receptor that regulates lipid metabolism genes including FASN. | Adipocyte differentiation and lipid storage. |
| INSIG1 | Regulates SREBP processing and thus FASN expression. | Feedback control of lipogenesis. |
| SCAP | Escorts SREBP to Golgi for activation, affecting FASN transcription. | Cholesterol and fatty acid synthesis regulation. |
| USP7 | Deubiquitinase that may stabilize FASN. | Potential regulator of FASN protein levels. |
| STUB1 | E3 ubiquitin ligase that may target FASN for degradation. | Post-translational regulation of FASN. |
How Is fatty acid synthase activity Regulated?
FASN activity is regulated at transcriptional, translational, and post-translational levels. Transcriptional regulation is primarily mediated by SREBP-1c and ChREBP, which are activated by insulin and glucose, respectively. AMPK phosphorylates and inhibits acetyl-CoA carboxylase, reducing malonyl-CoA supply, and also directly inhibits SREBP-1, thereby downregulating FASN. Post-translational modifications include lactylation, which inhibits FASN activity, and ubiquitination, which can target FASN for degradation. Additionally, FBXW7β loss-of-function enhances FASN-mediated lipogenesis, suggesting that the ubiquitin-proteasome system plays a role in regulating FASN.
fatty acid synthase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| FASN | Breast cancer brain metastasis | Knockout or knockdown in breast cancer cell lines; brain metastasis mouse models. |
| FASN | Colorectal cancer | Conditional knockout in intestinal epithelium; xenograft models. |
| FASN | Staphylococcus aureus infection | Macrophage-specific knockout; infection models. |
| FBXW7 | Colorectal cancer | Knockout of FBXW7β in colorectal cancer cells; mouse models. |
| FASN | Obesity and metabolic syndrome | Liver-specific knockout; high-fat diet models. |
Cancer
FASN is overexpressed in many cancers, including breast, prostate, colorectal, and ovarian cancers, where it supports the lipogenic phenotype required for rapid proliferation and survival. High FASN expression is associated with poor prognosis and metastasis, particularly in breast cancer brain metastasis. Inhibition of FASN reduces tumor growth in preclinical models, making it a promising therapeutic target. Loss of FBXW7β enhances FASN-mediated lipogenesis and promotes colorectal cancer growth, linking FASN to oncogenic signaling pathways.
Infectious Disease and Immunity
FASN-mediated lipid droplet formation enhances macrophage killing of Staphylococcus aureus, indicating a role for FASN in host defense. This suggests that modulating FASN activity could influence immune responses to bacterial infections. Further research is needed to fully understand the mechanisms involved.
Metabolic Disorders
Dysregulation of FASN is implicated in obesity, type 2 diabetes, and non-alcoholic fatty liver disease, where excessive lipogenesis contributes to pathology. Targeting FASN may offer therapeutic benefits for these metabolic conditions, although challenges remain due to the essential role of FASN in normal physiology.
From fatty acid synthase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does FASN loss affect tumor growth? | FASN knockout in cancer cell lines and xenografts. |
| How does FASN lactylation regulate activity? | Point mutation of lactylation sites in FASN; overexpression of mutant. |
| What is the role of FASN in macrophage killing? | Macrophage-specific FASN knockout; bacterial infection assays. |
| How does FBXW7β loss enhance FASN lipogenesis? | FBXW7β knockout in colorectal cancer cells; lipidomics. |
| Can FASN inhibition overcome drug resistance? | FASN overexpression in resistant cell lines; inhibitor treatment. |
| What is the structural basis of FASN catalysis? | Tagged knock-in of FASN for cryo-EM; point mutations of active sites. |
How to Study the fatty acid synthase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| CRISPR knockout | Loss of FASN protein and function | Cancer cell lines, mouse models. |
| Lipidomics | Fatty acid and lipid species | Assessing FASN activity in cells. |
| Western blot | FASN protein levels and modifications | Regulation studies. |
| Immunoprecipitation | Protein-protein interactions and modifications | Identifying FASN regulators. |
| Cryo-EM | Three-dimensional structure of FASN | Mechanistic studies. |
| Fluorescence microscopy | FASN localization and lipid droplets | Cellular imaging. |
| Metabolic flux analysis | Rate of fatty acid synthesis | Quantifying FASN activity. |
| RNA-seq | Transcriptional changes upon FASN manipulation | Pathway analysis. |
Genetic Knockout and Knockdown
CRISPR-Cas9 knockout of FASN or RNA interference can be used to deplete FASN and assess its role in cell proliferation, lipid synthesis, and tumor growth. These models help determine whether FASN is causally involved in a phenotype.
Metabolic and Lipidomic Profiling
Mass spectrometry-based lipidomics and metabolic flux analysis can measure the impact of FASN manipulation on fatty acid synthesis and lipid species. These methods provide quantitative readouts of FASN activity.
Post-Translational Modification Analysis
Western blotting with modification-specific antibodies, immunoprecipitation, and mass spectrometry can detect lactylation, acetylation, and ubiquitination of FASN. These techniques are essential for understanding how FASN activity is regulated.
Structural Biology and Imaging
Cryo-electron microscopy and X-ray crystallography can resolve FASN structure and conformational changes. Fluorescence microscopy can visualize FASN localization and lipid droplet formation in cells.
How CRISPR Can Be Used to Study GO:0004312 fatty acid synthase activity
Knockout
CRISPR-Cas9 knockout of FASN generates cell lines or animal models completely lacking FASN activity. These models are used to study the essentiality of FASN in development, metabolism, and cancer. For example, FASN knockout in cancer cells reduces proliferation and tumor growth.
Point Mutation
CRISPR-mediated point mutations can be introduced into FASN to study specific residues involved in catalysis or regulation. For instance, mutating lactylation sites can reveal their impact on FASN activity. Point mutations in active sites can also help dissect the catalytic mechanism.
Knock-in
Knock-in of tagged FASN (e.g., GFP or FLAG) allows for visualization and purification of the enzyme. This approach is useful for studying FASN localization, interactions, and post-translational modifications.
Overexpression
CRISPR activation or lentiviral overexpression of FASN can model the lipogenic phenotype observed in cancer. Overexpression models are used to test FASN inhibitors and to study the consequences of elevated FASN activity.
How EDITGENE Supports fatty acid synthase activity Research
Researchers studying fatty acid synthase activity-related genes often need to determine whether a candidate gene is causally involved in lipid metabolism, cancer progression, or immune function. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell models, enabling rigorous functional studies.
Contact EDITGENE today to design your custom CRISPR model for fatty acid synthase activity research.
Frequently Asked Questions About fatty acid synthase activity
What is fatty acid synthase activity?
Fatty acid synthase activity (GO:0004312) is the enzymatic function that synthesizes long-chain fatty acids from acetyl-CoA and malonyl-CoA using NADPH, as defined by the Gene Ontology.
What genes are involved in fatty acid synthase activity?
The primary gene is FASN, which encodes the multifunctional enzyme. Other genes such as FBXW7, SREBF1, and ACACA regulate or support FASN activity.
How is fatty acid synthase activity regulated?
FASN is regulated transcriptionally by SREBP-1c and ChREBP, and post-translationally by modifications like lactylation and ubiquitination.
What diseases are associated with fatty acid synthase activity?
FASN is linked to cancer, metabolic disorders, and infectious diseases. It is overexpressed in many cancers and supports tumor growth.
What is the role of FASN in cancer?
FASN provides fatty acids for membrane synthesis and signaling, supporting rapid cancer cell proliferation. Its inhibition reduces tumor growth.
How can I study fatty acid synthase activity in the lab?
Common methods include CRISPR knockout, lipidomics, Western blotting, and metabolic flux analysis.
What are the substrates of fatty acid synthase?
The substrates are acetyl-CoA, malonyl-CoA, and NADPH. The enzyme produces long-chain fatty acids, CoA, CO2, and NADP+.
Is fatty acid synthase a good drug target?
Yes, FASN is considered a promising target for cancer therapy, with several inhibitors in development.
What is the structure of fatty acid synthase?
Animal FASN is a homodimer with seven catalytic domains per monomer, arranged to allow substrate channeling.
How does lactylation affect FASN?
Lactylation of FASN inhibits its lipid synthesis activity, linking lactate metabolism to fatty acid production.
Conclusion
GO:0004312 fatty acid synthase activity is a central metabolic function with profound implications for cancer, immunity, and metabolic diseases. The multifunctional enzyme FASN executes this activity through a series of well-orchestrated catalytic steps, and its regulation is complex and tightly linked to cellular signaling. Continued research using advanced CRISPR models and multi-omics approaches will further illuminate the roles of FASN and aid in the development of targeted therapies.
References
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