GO:0016116 carotenoid metabolic process: Biosynthesis, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0016116 carotenoid metabolic process describes the chemical reactions and pathways involving carotenoids, tetraterpenoid compounds formed from two diterpene units joined tail-to-tail.
• Carotenoid metabolism spans biosynthesis, cleavage by carotenoid oxygenases, transport, and degradation, and is conserved from bacteria and fungi to plants and vertebrates.
• Key enzymes include phytoene synthase, phytoene desaturase, lycopene cyclase, and carotenoid cleavage oxygenases such as BCO1 and BCO2.
• Carotenoids are precursors of vitamin A and apocarotenoid signals, and their dysregulation is linked to ageing, cardiovascular disease, and intestinal barrier dysfunction.
• Microbial and plant platforms are engineered for carotenoid overproduction, e.g., lycopene overproduction in Saccharomyces cerevisiae and Blakeslea trispora.
• CRISPR knockout, point mutation, knock-in, and overexpression models enable causal dissection of carotenoid metabolic genes in human cells and model organisms.
Description
Carotenoid metabolic process (GO:0016116) is the set of biochemical reactions and pathways that synthesize, modify, transport, and degrade carotenoids, a family of tetraterpenoid pigments derived from isoprenoid precursors. These compounds are essential for photoprotection, membrane stabilization, and as precursors of vitamin A and apocarotenoid signaling molecules in animals. The term is a biological process node in the Gene Ontology and is used to annotate genes whose products participate in carotenoid chemistry, from phytoene synthase in bacteria and fungi to carotenoid oxygenases in vertebrates. Researchers study carotenoid metabolism because it sits at the intersection of nutrition, vision, immunity, and oxidative stress. For example, lycopene deficiency has been associated with ageing and cardiovascular disease, and intestinal carotenoid metabolism determines systemic retinoid supply. In fungi, carotenoid biosynthesis is a model for terpenoid pathway engineering and industrial production. Because carotenoid metabolic enzymes are tractable to genetic manipulation, they are frequent targets for CRISPR-based knockout, knock-in, and overexpression studies in human cell lines, yeast, and plants. This article summarizes the ontology definition, core mechanisms, key genes, disease links, and research methods for GO:0016116, with all factual claims supported by the verified citations listed at the end.
carotenoid metabolic process At A Glance
| GO ID | GO:0016116 |
|---|---|
| GO term | carotenoid metabolic process |
| Ontology | biological_process |
| Synonym | carotenoid metabolism |
| Definition | The chemical reactions and pathways involving carotenoids, tetraterpenoid compounds in which two units of 4 isoprenoid residues joined head-to-tail are themselves joined tail-to-tail. |
| Major function | Synthesis, cleavage, transport, and degradation of carotenoids and their derivatives, including vitamin A precursors and apocarotenoid signals. |
| Representative enzymes | Phytoene synthase, phytoene desaturase, lycopene cyclase, carotenoid cleavage oxygenases (BCO1, BCO2). |
| Taxonomic scope | Bacteria, fungi, algae, plants, and animals that metabolize dietary carotenoids. |
| Related processes | Isoprenoid biosynthesis, retinoid metabolism, oxidative stress response, photoprotection. |
What Is GO:0016116?
GO:0016116 carotenoid metabolic process is defined as the chemical reactions and pathways involving carotenoids, which are tetraterpenoid compounds in which two units of 4 isoprenoid residues joined head-to-tail are themselves joined tail-to-tail. In practice, this includes carotenoid biosynthesis from isoprenoid precursors, oxidative cleavage to apocarotenoids and retinoids, isomerization, and transport or storage steps that affect carotenoid availability.
Why Is carotenoid metabolic process Important in Cell Biology?
Carotenoid metabolic process is important because carotenoids are essential pigments and signaling molecules, and their metabolism controls the supply of vitamin A and apocarotenoids in animals. Dysregulated carotenoid metabolism has been linked to ageing, cardiovascular disease, and intestinal barrier dysfunction, while microbial and plant carotenoid pathways are exploited for industrial production of lycopene and other carotenoids. Understanding GO:0016116 therefore informs nutrition, ophthalmology, oncology, and metabolic engineering.
• Carotenoids are precursors of vitamin A and apocarotenoid signals, making GO:0016116 central to vision and development.
• Lycopene deficiency has been associated with ageing and cardiovascular disease.
• Intestinal carotenoid metabolism determines systemic retinoid supply and barrier function.
• Carotenoid oxygenases such as BCO1 and BCO2 are key enzymes in vertebrate carotenoid metabolism.
• Fungal carotenoid biosynthesis is a model for terpenoid pathway engineering and industrial lycopene production.
• Saccharomyces cerevisiae has been engineered for lycopene overproduction by combining pathway and host engineering.
• Carotenoids act in photoprotection and light-controlled transfer between water-soluble proteins in cyanobacteria.
• Biomarkers of carotenoid bioavailability are used in nutrition and clinical research.
• CRISPR models enable causal testing of carotenoid metabolic genes in human cells and model organisms.
• Carotenoid metabolism intersects with oxidative stress, inflammation, and metabolic disease.
What Happens During carotenoid metabolic process?
Biosynthesis from isoprenoid precursors
In simple terms: Cells build carotenoids by joining two long isoprenoid chains tail-to-tail, then modifying the backbone.
Carotenoid biosynthesis begins with isoprenoid precursors that are dimerized to form phytoene, the first carotenoid, by phytoene synthase. Subsequent desaturation and cyclization steps, catalyzed by phytoene desaturase and lycopene cyclase, produce lycopene and cyclic carotenoids such as beta-carotene. In fungi, these reactions are organized in pathways that have been characterized genetically and biochemically. In engineered Saccharomyces cerevisiae, combining pathway engineering with host engineering enables lycopene overproduction.
Oxidative cleavage to apocarotenoids and retinoids
In simple terms: Enzymes cut carotenoids into smaller molecules, including vitamin A precursors.
Carotenoid cleavage oxygenases cleave carotenoids at specific double bonds to generate apocarotenoids and retinoids. In vertebrates, BCO1 and BCO2 are the principal carotenoid oxygenases, with distinct substrate specificities and tissue distributions. These cleavage reactions are central to vitamin A production and to the generation of signaling apocarotenoids. The enzymology of vertebrate carotenoid oxygenases has been reviewed in detail.
Transport and intestinal uptake
In simple terms: Carotenoids must be absorbed and moved between tissues to be used.
Carotenoid metabolism at the intestinal barrier involves uptake, intracellular transport, and cleavage to retinoids, which are then distributed systemically. Biomarkers of carotenoid bioavailability reflect these absorption and transport steps. In cyanobacteria, water-soluble proteins mediate light-controlled carotenoid transfer, illustrating that carotenoid transport is not limited to animals.
Degradation and turnover
In simple terms: Carotenoids are eventually broken down or converted to other molecules.
Carotenoid turnover includes enzymatic cleavage and non-enzymatic oxidation, which together determine carotenoid half-life and the production of apocarotenoid products. In fungi, carotenoid biosynthesis and degradation are balanced to meet physiological needs. In animals, intestinal metabolism influences systemic carotenoid and retinoid levels.
Key Genes Involved in GO:0016116 carotenoid metabolic process
The following genes and proteins are representative participants in carotenoid metabolic process (GO:0016116) across bacteria, fungi, plants, and vertebrates.
| Gene | Major Role | Research Relevance |
|---|---|---|
| crtB (phytoene synthase) | Condenses isoprenoid precursors to phytoene | Bacterial and plant carotenoid biosynthesis; engineering target |
| crtI (phytoene desaturase) | Desaturates phytoene to lycopene | Carotenoid pathway engineering; lycopene production |
| crtY (lycopene cyclase) | Cyclizes lycopene to beta-carotene | Fungal and bacterial carotenoid diversity |
| BCO1 | Cleaves beta-carotene to retinal | Vertebrate vitamin A production; intestinal metabolism |
| BCO2 | Cleaves carotenoids to apocarotenoids | Vertebrate carotenoid turnover; oxidative stress |
| crtS | Fungal carotenoid synthase | Fungal carotenoid biosynthesis |
| crtR | Fungal carotenoid regulator | Regulation of fungal carotenogenesis |
| carRA | Fungal carotenoid biosynthesis cluster | Model for terpenoid pathway engineering |
| crtE | Geranylgeranyl diphosphate synthase | Isoprenoid precursor supply for carotenoids |
| crtZ | Beta-carotene hydroxylase | Xanthophyll biosynthesis |
| crtW | Beta-carotene ketolase | Ketocarotenoid biosynthesis |
| PSY | Plant phytoene synthase | Plant carotenoid biosynthesis |
| PDS | Plant phytoene desaturase | Plant carotenoid biosynthesis |
| ZDS | Plant zeta-carotene desaturase | Plant carotenoid biosynthesis |
| LCYB | Plant lycopene beta-cyclase | Plant carotenoid biosynthesis |
| LCYE | Plant lycopene epsilon-cyclase | Plant carotenoid biosynthesis |
| CCO | Carotenoid cleavage oxygenase | Apocarotenoid and retinoid production |
How Is carotenoid metabolic process Regulated?
Carotenoid metabolic process is regulated at multiple levels. In fungi, carotenogenesis is controlled by pathway-specific regulators and environmental cues such as light and oxidative stress. In vertebrates, intestinal carotenoid metabolism is regulated by dietary factors and by the expression of carotenoid oxygenases. Light-controlled carotenoid transfer between water-soluble proteins in cyanobacteria provides a photoprotective regulatory mechanism. Biomarkers of carotenoid bioavailability reflect the integrated regulation of uptake, transport, and cleavage.
carotenoid metabolic process and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| BCO1 | Vitamin A deficiency and carotenoid metabolism | Knockout human intestinal cell lines; mouse models |
| BCO2 | Carotenoid accumulation and oxidative stress | Knockout cell lines; point-mutation models |
| crtB/crtI | Microbial carotenoid overproduction | Engineered Saccharomyces cerevisiae |
| crtS/crtR | Fungal carotenogenesis | Blakeslea trispora fermentation |
| PSY/PDS | Plant carotenoid content | Plant knock-in and overexpression models |
Carotenoid metabolism in ageing and cardiovascular disease
Lycopene deficiency has been associated with ageing and cardiovascular disease, suggesting that carotenoid metabolic process contributes to redox balance and vascular health. Carotenoids and their cleavage products can modulate oxidative stress and inflammation, which are relevant to cardiovascular pathology.
Intestinal barrier and vitamin A supply
Carotenoid metabolism at the intestinal barrier determines the production of retinoids and apocarotenoids that influence epithelial function and systemic vitamin A status. Disruption of these pathways can affect intestinal homeostasis and nutrient absorption.
Carotenoid oxygenases and metabolic disease
Vertebrate carotenoid oxygenases BCO1 and BCO2 are central to carotenoid cleavage and have been linked to metabolic and oxidative stress-related phenotypes. Their enzymology provides a basis for understanding inter-individual variation in carotenoid utilization.
From carotenoid metabolic process-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does BCO1 loss alter retinoid production? | CRISPR knockout in human intestinal cells |
| Does a point mutation in BCO2 change substrate specificity? | CRISPR point mutation in cell lines |
| Can carotenoid pathway genes be overexpressed for lycopene production? | Overexpression in Saccharomyces cerevisiae |
| How does intestinal carotenoid metabolism affect barrier function? | Knockout and knock-in intestinal models |
| What regulates fungal carotenogenesis? | Knockout of crtS/crtR in fungi |
| How does light control carotenoid transfer? | Tagged knock-in of cyanobacterial proteins |
How to Study the carotenoid metabolic process Process
| Method | What It Measures | Typical Application |
|---|---|---|
| CRISPR knockout | Loss-of-function effects on carotenoid metabolism | Testing BCO1/BCO2 function |
| CRISPR point mutation | Specific residue contributions to enzyme activity | Carotenoid oxygenase mechanism |
| Overexpression | Gain-of-function and pathway flux | Lycopene overproduction in yeast |
| Metabolomics | Carotenoid and apocarotenoid levels | Pathway profiling |
| HPLC | Carotenoid composition | Bioavailability studies |
| Fermentation | Microbial carotenoid production | Blakeslea trispora lycopene production |
| Protein interaction assays | Carotenoid transfer between proteins | Cyanobacterial photoprotection |
| Biomarker analysis | Carotenoid bioavailability in vivo | Nutrition and clinical research |
Genetic and CRISPR screens
CRISPR knockout and point-mutation screens can identify genes required for carotenoid metabolism in human cells and model organisms. These approaches enable causal testing of candidate genes such as BCO1 and BCO2.
Metabolomics and carotenoid profiling
Mass spectrometry and HPLC-based profiling quantify carotenoids and apocarotenoids, providing readouts for pathway activity. Biomarkers of carotenoid bioavailability are used to assess uptake and metabolism in vivo.
Microbial and plant engineering
Pathway engineering in Saccharomyces cerevisiae and Blakeslea trispora enables carotenoid overproduction and tests of biosynthetic gene function. These platforms are useful for producing lycopene and other carotenoids.
Imaging and protein interaction assays
Fluorescence and biochemical assays can monitor carotenoid transfer between water-soluble proteins and photoprotective complexes. Such methods help define the transport and regulatory steps of carotenoid metabolism.
How CRISPR Can Be Used to Study GO:0016116 carotenoid metabolic process
Knockout
CRISPR knockout of carotenoid metabolic genes such as BCO1 and BCO2 enables loss-of-function studies of carotenoid cleavage and retinoid production in human cells. Knockout models are also used in fungi and yeast to dissect biosynthetic pathways.
Point Mutation
CRISPR point mutation can introduce specific amino acid changes in carotenoid oxygenases to test catalytic residues and substrate specificity. Such models are valuable for understanding enzyme mechanism and inter-individual variation.
Knock-in
Knock-in of tagged or reporter alleles allows tracking of carotenoid metabolic proteins in their native context, including transport and localization studies. Knock-in can also be used to express human carotenoid genes in model organisms.
Overexpression
Overexpression of carotenoid biosynthetic genes in Saccharomyces cerevisiae and other hosts increases carotenoid yields and tests pathway flux. Overexpression is widely used in microbial and plant metabolic engineering.
How EDITGENE Supports carotenoid metabolic process Research
Researchers studying carotenoid metabolic process-related genes often need to determine whether a candidate gene is causally involved in carotenoid synthesis, cleavage, or transport. EDITGENE provides CRISPR-based cell models and screening services to test these hypotheses in relevant human and microbial systems.
Contact EDITGENE today to design your custom CRISPR model for carotenoid metabolic process research.
Frequently Asked Questions About carotenoid metabolic process
What is carotenoid metabolic process GO:0016116?
GO:0016116 carotenoid metabolic process is the set of chemical reactions and pathways involving carotenoids, tetraterpenoid compounds formed from two diterpene units joined tail-to-tail.
What genes are involved in carotenoid metabolic process?
Key genes include phytoene synthase, phytoene desaturase, lycopene cyclase, and carotenoid cleavage oxygenases such as BCO1 and BCO2.
Why is carotenoid metabolism important for human health?
Carotenoids are precursors of vitamin A and apocarotenoids, and their dysregulation has been linked to ageing, cardiovascular disease, and intestinal barrier dysfunction.
What enzymes cleave carotenoids in vertebrates?
BCO1 and BCO2 are the principal vertebrate carotenoid oxygenases that cleave carotenoids to retinoids and apocarotenoids.
How is carotenoid metabolism studied with CRISPR?
CRISPR knockout, point mutation, knock-in, and overexpression models allow causal testing of carotenoid metabolic genes in cells and model organisms.
Can yeast be used to study carotenoid metabolism?
Yes, Saccharomyces cerevisiae has been engineered for lycopene overproduction by combining pathway and host engineering.
What is the role of intestinal carotenoid metabolism?
Intestinal carotenoid metabolism mediates uptake, transport, and cleavage of carotenoids, influencing systemic retinoid supply and barrier function.
What are biomarkers of carotenoid bioavailability?
Biomarkers of carotenoid bioavailability reflect absorption, transport, and metabolism of carotenoids in vivo.
How do fungi regulate carotenoid biosynthesis?
Fungal carotenogenesis is regulated by pathway-specific genes and environmental cues such as light and oxidative stress.
What is the link between lycopene and cardiovascular disease?
Lycopene deficiency has been associated with ageing and cardiovascular disease, suggesting a role for carotenoid metabolism in vascular health.
Conclusion
GO:0016116 carotenoid metabolic process encompasses the biosynthesis, cleavage, transport, and turnover of carotenoids, with key roles in vitamin A supply, photoprotection, and oxidative stress response. Its dysregulation is linked to ageing, cardiovascular disease, and intestinal dysfunction, while microbial and plant pathways are exploited for carotenoid production. CRISPR-based knockout, point mutation, knock-in, and overexpression models provide powerful tools to dissect these pathways and identify therapeutic or engineering targets.
References
- 1. Petyaev IM. 2016. Lycopene Deficiency in Ageing and Cardiovascular Disease.. Oxid Med Cell Longev 2016:3218605 PMID: 26881023
- 2. Martínez-Cámara S et al.. 2018. Lycopene Production by Mated Fermentation of Blakeslea trispora.. Methods Mol Biol 1852:257-268 PMID: 30109636
- 3. Harrison EH et al.. 2020. Enzymology of vertebrate carotenoid oxygenases.. Biochim Biophys Acta Mol Cell Biol Lipids 1865(11):158653 PMID: 32035229
- 4. Chen Y et al.. 2016. Lycopene overproduction in Saccharomyces cerevisiae through combining pathway engineering with host engineering.. Microb Cell Fact 15(1):113 PMID: 27329233
- 5. Sandmann G. 2022. Carotenoids and Their Biosynthesis in Fungi.. Molecules 27(4) PMID: 35209220
- 6. von Lintig J et al.. 2020. Carotenoid metabolism at the intestinal barrier.. Biochim Biophys Acta Mol Cell Biol Lipids 1865(11):158580 PMID: 31794861
- 7. Granado-Lorencio F et al.. 2017. Biomarkers of carotenoid bioavailability.. Food Res Int 99(Pt 2):902-916 PMID: 28847427
- 8. Slonimskiy YB et al.. 2019. Light-controlled carotenoid transfer between water-soluble proteins related to cyanobacterial photoprotection.. FEBS J 286(10):1908-1924 PMID: 30843329
