GO:0003870 5-aminolevulinate synthase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0003870 defines the molecular function that catalyzes the condensation of glycine and succinyl-CoA to form 5-aminolevulinate, the first committed step of heme biosynthesis.
• The reaction is pyridoxal 5'-phosphate (PLP)-dependent and occurs in the mitochondrial matrix, with the enzyme encoded by ALAS1 (ubiquitous) and ALAS2 (erythroid-specific) in mammals.
• 5-aminolevulinate synthase (ALAS) is the rate-limiting enzyme of heme synthesis, and its activity is tightly regulated by heme, succinyl-CoA availability, and developmental signals.
• Dysregulation of ALAS activity is linked to X-linked sideroblastic anemia (ALAS2 mutations) and acute hepatic porphyrias (ALAS1 induction), making it a therapeutic target.
• Structural and mechanistic studies have revealed conformational dynamics and a conserved catalytic fold shared across species, from bacteria to humans.
• CRISPR-based knockout, point-mutation, and knock-in models enable precise dissection of ALAS function in heme-related diseases and metabolic engineering.
Description
5-aminolevulinate synthase (ALAS) activity, encoded by GO:0003870, is the molecular function responsible for the first and rate-limiting step of heme biosynthesis in metazoans, fungi, and some bacteria. This enzymatic activity catalyzes the pyridoxal 5'-phosphate (PLP)-dependent condensation of glycine and succinyl-CoA to yield 5-aminolevulinate (ALA), carbon dioxide, and coenzyme A. Because heme is essential for oxygen transport, electron transfer, and numerous metabolic reactions, ALAS activity sits at a critical regulatory node connecting cellular metabolism to heme production. Researchers study GO:0003870 to understand how heme synthesis is controlled, how its dysregulation leads to porphyrias and sideroblastic anemias, and how the enzyme can be engineered for biotechnological production of ALA. The activity is encoded by two distinct genes in mammals: ALAS1, which is ubiquitously expressed and subject to feedback inhibition by heme, and ALAS2, which is erythroid-specific and regulated by iron and erythropoiesis. Structural and kinetic studies have provided detailed insights into the catalytic mechanism, including the roles of conserved residues and conformational changes during substrate binding and product release. Given its central role in heme biology, ALAS activity is a prime target for CRISPR-based functional genomics, allowing researchers to create knockout, point-mutation, and knock-in models that reveal how specific residues and regulatory elements contribute to enzyme function and disease. This article synthesizes authoritative QuickGO data and verified PubMed literature to provide a comprehensive overview of GO:0003870 for researchers, clinicians, and biotechnology engineers.
5-aminolevulinate synthase activity At A Glance
| GO ID | GO:0003870 |
|---|---|
| GO term | 5-aminolevulinate synthase activity |
| Ontology | molecular_function |
| Synonym | 5-aminolevulinate synthetase activity; 5-aminolevulinic acid synthase activity; ALAS activity; ALA synthase activity; delta-aminolevulinate synthase activity; succinyl-CoA:glycine C-succinyltransferase (decarboxylating) |
| Major function | Catalyzes the first step of heme biosynthesis: condensation of glycine and succinyl-CoA to form 5-aminolevulinate, CO2, and CoA |
| Cofactor | Pyridoxal 5'-phosphate (PLP) |
| Subcellular location | Mitochondrial matrix |
| Representative genes | ALAS1 (ubiquitous), ALAS2 (erythroid-specific) in mammals; HemA in bacteria |
| Reaction direction | Irreversible under physiological conditions |
| Pathology | Mutations in ALAS2 cause X-linked sideroblastic anemia; ALAS1 induction is implicated in acute hepatic porphyrias |
What Is GO:0003870?
GO:0003870, 5-aminolevulinate synthase activity, is defined as the catalysis of the reaction: glycine + H+ + succinyl-CoA = 5-aminolevulinate + CO2 + CoA. In other words, it is the enzymatic activity that joins glycine and succinyl-CoA to form 5-aminolevulinate, releasing carbon dioxide and coenzyme A. This activity requires pyridoxal 5'-phosphate (PLP) as a cofactor and represents the first committed step in heme biosynthesis.
Why Is 5-aminolevulinate synthase activity Important in Cell Biology?
GO:0003870 is critically important because it governs the rate-limiting step of heme biosynthesis, a process essential for oxygen transport, mitochondrial respiration, and diverse metabolic reactions. Dysregulation of this activity leads to severe human disorders, including X-linked sideroblastic anemia and acute hepatic porphyrias, and it is a target for therapeutic intervention and metabolic engineering. Understanding its mechanism and regulation is fundamental to hematology, hepatology, and biotechnology.
• Rate-limiting step of heme biosynthesis, controlling the flux of the entire pathway.
• Mutations in ALAS2 cause X-linked sideroblastic anemia, a disorder of heme synthesis in erythroid cells.
• Induction of ALAS1 by drugs or hormones can precipitate acute hepatic porphyrias.
• ALAS activity is essential for mitochondrial function and cellular respiration.
• The enzyme is a target for engineering improved 5-aminolevulinate production in biotechnology.
• Heme feedback inhibition of ALAS1 maintains metabolic homeostasis.
• ALAS2 regulation by iron and erythropoiesis links heme synthesis to red blood cell development.
• Structural studies of ALAS provide a framework for designing inhibitors and activators.
• CRISPR models of ALAS genes enable precise dissection of its role in disease and development.
• ALAS activity is conserved across species, making model organisms valuable for mechanistic studies.
What Happens During 5-aminolevulinate synthase activity?
Substrate Binding and Catalysis
In simple terms: The enzyme grabs glycine and succinyl-CoA and joins them together to make ALA.
The catalytic cycle begins with the binding of glycine and succinyl-CoA to the active site of ALAS. Glycine forms a Schiff base with the PLP cofactor, facilitating decarboxylation and condensation with succinyl-CoA. This leads to the release of CO2 and CoA, and the formation of 5-aminolevulinate. The reaction is irreversible and requires a conserved lysine residue for PLP attachment.
Conformational Dynamics
In simple terms: The enzyme changes shape to allow substrates in and products out.
Structural studies of ALAS from Rhodopseudomonas palustris revealed multiple conformations of the enzyme, indicating that substrate binding and product release are accompanied by significant conformational changes. These dynamics are essential for catalysis and are conserved across species, as seen in mammalian ALAS.
Heme Feedback Inhibition
In simple terms: When heme levels are high, heme binds to the enzyme and stops it from working.
In non-erythroid cells, ALAS1 activity is feedback-inhibited by heme, which binds to a heme-regulatory motif and promotes degradation or inhibits enzyme activity. This ensures that heme synthesis matches cellular demand. In erythroid cells, ALAS2 lacks this heme-responsive motif and is instead regulated by iron availability and erythropoiesis.
Role in Heme Biosynthesis Pathway
In simple terms: ALA made by ALAS is the starting material for all heme.
The 5-aminolevulinate produced by ALAS is the first committed precursor of heme. It is subsequently converted by a series of enzymes in the mitochondria and cytoplasm to yield heme, which is then incorporated into hemoproteins. Thus, ALAS activity determines the overall rate of heme production.
Key Genes Involved in GO:0003870 5-aminolevulinate synthase activity
The following genes encode proteins that either possess 5-aminolevulinate synthase activity or directly regulate it, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ALAS1 | Ubiquitous 5-aminolevulinate synthase; rate-limiting for heme synthesis in non-erythroid tissues | Target for acute hepatic porphyria therapies; regulated by heme and drugs |
| ALAS2 | Erythroid-specific 5-aminolevulinate synthase; essential for hemoglobin production | Mutations cause X-linked sideroblastic anemia; regulated by iron |
| HemA | Bacterial 5-aminolevulinate synthase; first step of heme biosynthesis in bacteria | Model for structural and mechanistic studies; used in biotechnology |
| PLP | Pyridoxal 5'-phosphate cofactor required for ALAS activity | Essential for catalysis; deficiency affects heme synthesis |
| Succinyl-CoA | Substrate for ALAS; provides the carbon skeleton for ALA | Links TCA cycle to heme biosynthesis |
| Glycine | Substrate for ALAS; provides the nitrogen and part of the carbon skeleton | Amino acid precursor for heme |
| Heme | End product of the pathway; feedback inhibitor of ALAS1 | Regulates ALAS1 stability and activity |
| Iron | Regulates ALAS2 translation via IRP/IRE system | Links iron metabolism to heme synthesis |
| Erythropoietin | Stimulates erythropoiesis and ALAS2 expression | Hormonal regulation of red blood cell production |
| Tryptophan | Hypothesized to modulate ALAS activity and heme utilization | Potential therapy for acute hepatic porphyrias |
| TDO2 | Tryptophan 2,3-dioxygenase; degrades tryptophan and may affect heme utilization | Target for porphyria therapy |
| SLC25A38 | Mitochondrial glycine transporter; supplies glycine for ALAS | Mutations cause sideroblastic anemia |
| ABCB7 | Mitochondrial iron transporter; affects iron availability for ALAS2 | Linked to sideroblastic anemia with ataxia |
| FECH | Ferrochelatase; inserts iron into protoporphyrin to form heme | Downstream of ALAS; defects cause erythropoietic protoporphyria |
| CPOX | Coproporphyrinogen oxidase; heme biosynthesis enzyme | Defects cause hereditary coproporphyria |
| PPOX | Protoporphyrinogen oxidase; heme biosynthesis enzyme | Defects cause variegate porphyria |
| UROS | Uroporphyrinogen III synthase; heme biosynthesis enzyme | Defects cause congenital erythropoietic porphyria |
| GATA1 | Erythroid transcription factor; regulates ALAS2 expression | Controls erythroid-specific heme synthesis |
How Is 5-aminolevulinate synthase activity Regulated?
ALAS activity is regulated at multiple levels. In non-erythroid cells, ALAS1 is feedback-inhibited by heme, which promotes protein degradation and inhibits mitochondrial import. Additionally, ALAS1 expression is induced by drugs, hormones, and fasting, which can precipitate acute porphyrias. In erythroid cells, ALAS2 is regulated by iron via the iron-responsive element (IRE) in its mRNA, and by erythropoietin and GATA1 during erythroid differentiation. Post-translational modifications and conformational changes also modulate ALAS activity.
5-aminolevulinate synthase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ALAS2 | X-linked sideroblastic anemia | ALAS2 knockout or point-mutation knock-in in erythroid cell lines (e.g., K562, CD34+ cells) |
| ALAS1 | Acute hepatic porphyrias | ALAS1 overexpression or knockout in hepatocyte-like cells (e.g., HepG2, primary hepatocytes) |
| HemA | Bacterial heme biosynthesis | HemA knockout in E. coli or R. palustris for metabolic engineering |
| SLC25A38 | Sideroblastic anemia | SLC25A38 knockout in erythroid cells to study glycine transport |
| FECH | Erythropoietic protoporphyria | FECH knockout or point-mutation models in erythroid cells |
X-linked Sideroblastic Anemia
Mutations in ALAS2 that reduce 5-aminolevulinate synthase activity cause X-linked sideroblastic anemia, characterized by defective heme synthesis, iron overload in mitochondria, and ineffective erythropoiesis. The disease highlights the critical role of ALAS2 in erythroid heme production.
Acute Hepatic Porphyrias
Acute hepatic porphyrias are caused by deficiencies in heme biosynthesis enzymes downstream of ALAS, leading to accumulation of neurotoxic intermediates. Induction of ALAS1 by drugs or hormones exacerbates the disease, and therapies aim to reduce ALAS1 activity or heme utilization.
Metabolic and Biotechnological Applications
Engineered ALAS variants with enhanced activity and stability are used for microbial production of 5-aminolevulinate, a precursor for heme and porphyrin-based products. Rational design has improved enzyme performance for industrial applications.
From 5-aminolevulinate synthase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of ALAS1 loss on heme synthesis and cell viability? | ALAS1 knockout in HepG2 or primary hepatocytes |
| How do ALAS2 mutations cause sideroblastic anemia? | ALAS2 point-mutation knock-in in K562 or CD34+ erythroid cells |
| Can engineered ALAS improve ALA production? | ALAS overexpression or knock-in in E. coli or R. palustris |
| How is ALAS1 regulated by heme? | ALAS1 tagged knock-in for degradation studies in HeLa or HepG2 |
| What is the role of ALAS2 in erythropoiesis? | ALAS2 knockout in mouse models or human erythroid cultures |
| How do disease-associated mutations affect ALAS structure? | Point-mutation knock-in of ALAS2 variants in HEK293T for structural studies |
How to Study the 5-aminolevulinate synthase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Colorimetric ALA assay | 5-aminolevulinate production | Enzyme kinetics and inhibitor testing |
| X-ray crystallography | Three-dimensional structure | Mechanistic studies and drug design |
| RNA-seq | ALAS1/ALAS2 mRNA levels | Regulation by heme, iron, or drugs |
| Western blot | ALAS protein levels | Protein stability and degradation studies |
| CRISPR knockout | Loss-of-function phenotypes | Gene function in heme synthesis |
| CRISPR knock-in | Mutant ALAS expression | Disease modeling and structure-function analysis |
| Proteomics | Protein interactions and modifications | Identifying ALAS regulators |
| Metabolomics | Heme pathway intermediates | Flux analysis and disease biomarker discovery |
Enzymatic Activity Assays
5-aminolevulinate synthase activity is typically measured by monitoring the formation of ALA using colorimetric or fluorometric assays. These methods are essential for characterizing wild-type and mutant enzymes.
Structural Biology
X-ray crystallography and cryo-EM have been used to determine the structure of ALAS from various species, revealing conformational changes and substrate binding. These studies inform rational design of inhibitors and engineered variants.
Gene Expression Analysis
RNA-seq and qPCR are used to measure ALAS1 and ALAS2 mRNA levels under different conditions, such as heme depletion or erythropoietin stimulation.
CRISPR Screening
Genome-wide CRISPR knockout screens can identify genes that regulate ALAS activity or heme biosynthesis, providing insights into pathway crosstalk and disease modifiers.
How CRISPR Can Be Used to Study GO:0003870 5-aminolevulinate synthase activity
Knockout
CRISPR knockout of ALAS1 or ALAS2 enables researchers to study the consequences of loss of 5-aminolevulinate synthase activity on heme synthesis, cell viability, and mitochondrial function. Knockout models are valuable for validating drug targets and understanding disease mechanisms.
Point Mutation
Introducing disease-associated point mutations into ALAS2 (e.g., those found in sideroblastic anemia) using CRISPR base editing or homology-directed repair allows precise modeling of enzyme dysfunction and structural studies.
Knock-in
Knock-in of tagged ALAS1 or ALAS2 (e.g., FLAG, GFP) facilitates protein localization, interaction, and degradation studies. Knock-in of engineered ALAS variants can improve ALA production in biotechnology.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of ALAS1/ALAS2 can boost heme synthesis for metabolic engineering or to study feedback regulation.
How EDITGENE Supports 5-aminolevulinate synthase activity Research
Researchers studying 5-aminolevulinate synthase activity-related genes often need to determine whether a candidate gene is causally involved in heme biosynthesis, disease pathogenesis, or metabolic engineering. EDITGENE provides comprehensive CRISPR-based services to create precise cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for 5-aminolevulinate synthase activity research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| ALAS1 Knockout HEK293 Cell Line | EDJ-KQ3366 | Human | 211 | Details Get a Quote |
| ALAS2 Knockout HEK293 Cell Line | EDJ-KQ4030 | Human | 212 | Details Get a Quote |
| ALAS1 Knockout A-549 Cell Line | EDJ-KQ26372 | Human | 211 | Details Get a Quote |
| ALAS1 Knockout HCT 116 Cell Line | EDJ-KQ26374 | Human | 211 | Details Get a Quote |
| ALAS1 Knockout HeLa Cell Line | EDJ-KQ26375 | Human | 211 | Details Get a Quote |
| ALAS2 Knockout HeLa Cell Line | EDJ-KQ52589 | Human | 212 | Details Get a Quote |
| ALAS2 Knockout A-549 Cell Line | EDJ-KQ61067 | Human | 212 | Details Get a Quote |
| ALAS2 Knockout HCT 116 Cell Line | EDJ-KQ69550 | Human | 212 | Details Get a Quote |
Displaying Records 1 To 8 Of 8 Records
Frequently Asked Questions About 5-aminolevulinate synthase activity
What is 5-aminolevulinate synthase activity?
5-aminolevulinate synthase activity (GO:0003870) is the enzymatic function that catalyzes the first step of heme biosynthesis, converting glycine and succinyl-CoA to 5-aminolevulinate, CO2, and CoA.
What genes are involved in 5-aminolevulinate synthase activity?
In mammals, ALAS1 encodes the ubiquitous enzyme and ALAS2 encodes the erythroid-specific enzyme. In bacteria, HemA encodes the enzyme.
What is the role of ALAS in heme biosynthesis?
ALAS catalyzes the rate-limiting step of heme biosynthesis, producing 5-aminolevulinate, which is subsequently converted to heme through a series of enzymatic reactions.
How is 5-aminolevulinate synthase activity regulated?
ALAS1 is feedback-inhibited by heme and induced by drugs or hormones, while ALAS2 is regulated by iron and erythropoiesis.
What diseases are associated with ALAS mutations?
Mutations in ALAS2 cause X-linked sideroblastic anemia, and dysregulation of ALAS1 is implicated in acute hepatic porphyrias.
What is the reaction catalyzed by 5-aminolevulinate synthase?
The enzyme catalyzes: glycine + H+ + succinyl-CoA = 5-aminolevulinate + CO2 + CoA.
What cofactor is required for ALAS activity?
Pyridoxal 5'-phosphate (PLP) is an essential cofactor for ALAS activity.
Where does 5-aminolevulinate synthase act in the cell?
ALAS is located in the mitochondrial matrix, where it catalyzes the first step of heme biosynthesis.
Can CRISPR be used to study ALAS function?
Yes, CRISPR knockout, point mutation, and knock-in models are powerful tools to dissect ALAS function in heme synthesis and disease.
How can I measure 5-aminolevulinate synthase activity?
Activity is typically measured using colorimetric assays that detect 5-aminolevulinate production, or by monitoring heme synthesis in cell models.
Conclusion
5-aminolevulinate synthase activity (GO:0003870) is a fundamental molecular function that initiates heme biosynthesis, with critical roles in human health and disease. Its tight regulation and structural complexity make it a compelling target for research in hematology, hepatology, and biotechnology. CRISPR-based models offer unprecedented opportunities to dissect its mechanism and develop therapeutic strategies. EDITGENE provides comprehensive services to support these investigations, from knockout and point-mutation models to library screening and bioinformatics.
References
- 1. Stojanovski BM et al.. 2019. 5-Aminolevulinate synthase catalysis: The catcher in heme biosynthesis.. Mol Genet Metab 128(3):178-189 PMID: 31345668
- 2. Zhang T et al.. 2022. Crystal structure of 5-Aminolevulinate synthase HemA from Rhodopseudomonas palustris presents multiple conformations.. Biochem Biophys Res Commun 609:100-104 PMID: 35427926
- 3. Du S et al.. 2025. Rational Design Engineering of 5-Aminolevulinate Synthase with Activity and Stability Enhancement.. J Agric Food Chem 73(3):1892-1901 PMID: 39772634
- 4. Badawy AA. 2019. Hypothesis: Metabolic targeting of 5-aminolevulinate synthase by tryptophan and inhibitors of heme utilisation by tryptophan 2,3-dioxygenase as potential therapies of acute hepatic porphyrias.. Med Hypotheses 131:109314 PMID: 31443750
- 5. Ferreira GC et al.. 1993. Expression of mammalian 5-aminolevulinate synthase in Escherichia coli. Overproduction, purification, and characterization.. J Biol Chem 268(1):584-90 PMID: 8416963
- 6. Ikushiro H et al.. 2018. Heme-dependent Inactivation of 5-Aminolevulinate Synthase from Caulobacter crescentus.. Sci Rep 8(1):14228 PMID: 30242198
- 7. Hunter GA et al.. 2009. 5-aminolevulinate synthase: catalysis of the first step of heme biosynthesis.. Cell Mol Biol (Noisy-le-grand) 55(1):102-10 PMID: 19268008
- 8. Essig DA et al.. 1990. Regulation of 5'-aminolevulinate synthase activity in overloaded skeletal muscle.. Am J Physiol 259(2 Pt 1):C310-4 PMID: 2382704
