GO:0052722 fatty acid in-chain hydroxylase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0052722 describes fatty acid in-chain hydroxylase activity, the catalysis of fatty acid + O2 + 2 NADPH + H+ to a fatty acid bearing an in-chain hydroxy group, plus 2 NADP+ and H2O [1, 2].
• The reaction is performed by cytochrome P450 monooxygenases that insert a hydroxyl group at a non-terminal, internal carbon of a fatty acid chain [1, 3, 8].
• Fungal CYP505 enzymes are self-sufficient in-chain hydroxylases that fuse a P450 domain to an NADPH-dependent reductase domain [1, 3].
• Plant microsomal laurate in-chain hydroxylases were among the first characterized enzymes of this activity and are inducible and substrate-selective [5, 8].
• In-chain hydroxylation and related P450 oxidations of fatty acids can initiate dicarboxylic fatty acid formation and generate desaturated products such as Delta-3-valproic acid [4, 6].
• Studying GO:0052722 requires combining enzyme assays, structural biology, heterologous expression and CRISPR-based cell models to link catalytic activity to cellular and disease phenotypes [1, 3, 7].
Description
GO:0052722, fatty acid in-chain hydroxylase activity, is a molecular function in which a fatty acid is oxidized at an internal, non-terminal carbon to introduce a hydroxy group, consuming O2 and NADPH and releasing NADP+ and water [1, 2]. This activity is distinct from terminal omega-hydroxylation and from desaturation because the oxygen is inserted into the hydrocarbon chain rather than at the carboxyl end or as a double bond [1, 3]. The reaction is catalyzed by cytochrome P450 monooxygenases, a large superfamily of heme-thiolate enzymes that use a P450 domain to activate molecular oxygen and a redox partner to deliver electrons from NADPH [2, 7]. Researchers care about GO:0052722 because in-chain hydroxylated fatty acids are precursors of diverse bioactive lipids, including dicarboxylic fatty acids and oxidized metabolites that influence plant development, microbial physiology and drug metabolism [4, 6]. The best-studied examples include the plant laurate in-chain hydroxylase from Helianthus tuberosus microsomes, which is induced and highly specific for lauric acid [5, 8], and the fungal CYP505E subfamily, whose members act as self-sufficient in-chain hydroxylases on fatty acids [1, 3]. Myxobacterial CYP267B1 further shows how structural features dictate oxidation of medium-chain fatty acids. Because the same P450 fold can perform in-chain hydroxylation, terminal hydroxylation or desaturation depending on active-site geometry, GO:0052722 is a useful functional annotation for interpreting enzyme assays, genome mining and metabolic engineering experiments [1, 3, 7]. It also provides a framework for asking how mutations, expression changes or species differences alter fatty acid oxidation in health and disease [2, 6].
fatty acid in-chain hydroxylase activity At A Glance
| GO ID | GO:0052722 |
|---|---|
| GO term | fatty acid in-chain hydroxylase activity |
| Ontology | molecular_function |
| Synonym | none |
| Major function | Catalysis of fatty acid + O2 + 2 NADPH + H+ = fatty acid with in-chain hydroxy group + 2 NADP+ + H2O |
| Reaction type | Oxidation-reduction; monooxygenation of an internal fatty acid carbon |
| Cofactors | O2, NADPH, H+; heme iron in cytochrome P450 enzymes |
| Representative enzymes | CYP505E3, plant laurate in-chain hydroxylase, CYP267B1, CYP94C1 |
| Substrate examples | Lauric acid, medium-chain fatty acids, valproic acid |
What Is GO:0052722?
In simple terms, GO:0052722 describes an enzyme activity that adds an -OH group to a carbon inside a fatty acid chain, not at the very end. The official definition is: Catalysis of the reaction: fatty acid + O2 + 2 NADPH + H+ = fatty acid with in-chain hydroxy group + 2 NADP+ + H2O. This means the enzyme uses molecular oxygen and reducing power from NADPH to insert one oxygen atom into the fatty acid as a hydroxy group, while the other oxygen atom is reduced to water and NADPH is oxidized to NADP+ [1, 2].
Why Is fatty acid in-chain hydroxylase activity Important in Cell Biology?
GO:0052722 matters because in-chain hydroxylation is a rate- and route-determining step in fatty acid oxidation, converting simple fatty acids into hydroxylated intermediates that can be further oxidized to dicarboxylic acids or desaturated products [4, 6]. These reactions influence plant wound and jasmonate responses, microbial lipid metabolism and the metabolic fate of drugs such as valproic acid [4, 6]. Because the reaction is catalyzed by cytochrome P450 enzymes with tunable substrate specificity, it is also a target for metabolic engineering and biocatalysis, where self-sufficient in-chain hydroxylases such as CYP505E3 can be used to produce hydroxy fatty acids [1, 3]. Understanding GO:0052722 therefore connects enzyme mechanism, structural biology, cell physiology and translational applications [2, 7].
• Defines a specific P450-dependent oxidation that inserts a hydroxy group at an internal fatty acid carbon [1, 2].
• Provides a precursor route to dicarboxylic fatty acids, which are important in plant development and lipid catabolism.
• Contributes to the metabolism of xenobiotics and drugs such as valproic acid through in-chain desaturation and oxidation.
• Enables production of hydroxy fatty acids as industrial and pharmaceutical building blocks via biocatalysis [1, 3].
• Explains substrate selectivity differences among plant, fungal and bacterial P450 enzymes [5, 7, 8].
• Supports genome mining and functional annotation of uncharacterized P450s in the CYP505E subfamily.
• Links enzyme structure to catalytic outcome, helping distinguish in-chain hydroxylation from terminal hydroxylation.
• Offers a testable function for CRISPR knockout, knock-in and overexpression studies in cell and animal models [1, 3].
What Happens During fatty acid in-chain hydroxylase activity?
Substrate binding and active-site recognition
In simple terms: The enzyme first grabs the fatty acid and positions it so that the correct internal carbon sits next to the reactive heme iron.
Cytochrome P450 enzymes of this class bind fatty acids in a hydrophobic substrate channel above the heme, and the position of the substrate determines which carbon is hydroxylated [1, 7]. Plant microsomal laurate in-chain hydroxylase is highly specific for lauric acid, showing that substrate recognition is selective [5, 8]. Structural work on CYP267B1 demonstrates how medium-chain fatty acids are accommodated and oriented for oxidation.
Oxygen activation and electron transfer
In simple terms: The enzyme uses electrons from NADPH to split oxygen and create a powerful oxidizing species.
The catalytic cycle requires delivery of two electrons from NADPH to the P450 heme, followed by binding and activation of O2 to form a reactive iron-oxo intermediate. In self-sufficient CYP505 enzymes, the P450 domain is fused to a diflavin reductase domain that supplies electrons from NADPH, so no separate redox partner is needed [1, 3]. This architecture couples NADPH oxidation to fatty acid hydroxylation.
In-chain hydroxylation and product formation
In simple terms: The activated oxygen is inserted into an internal carbon of the fatty acid, creating a hydroxy group.
The reactive heme intermediate abstracts hydrogen from an internal methylene carbon and rebounds the oxygen to form the in-chain hydroxy fatty acid, consuming O2 and NADPH and releasing water [1, 2]. The reaction is regioselective: CYP505E3 acts as an omega-7 in-chain hydroxylase on fatty acids. Plant laurate in-chain hydroxylase similarly introduces a hydroxy group at an internal position of lauric acid [5, 8].
Downstream fates of in-chain hydroxylated fatty acids
In simple terms: The hydroxy fatty acid can be further converted into other products, such as dicarboxylic acids or desaturated fatty acids.
In-chain hydroxylated fatty acids can be oxidized further; Arabidopsis CYP94C1 catalyzes dicarboxylic fatty acid formation in vitro, linking in-chain oxidation to fatty acid catabolism. P450 enzymes can also catalyze in-chain desaturation, as shown for valproic acid conversion to Delta-3-valproic acid by CYP3A1. These downstream reactions expand the metabolic impact of GO:0052722 beyond the initial hydroxy product [4, 6].
Key Genes Involved in GO:0052722 fatty acid in-chain hydroxylase activity
The following genes and proteins are directly associated with fatty acid in-chain hydroxylase activity or with closely related P450-dependent fatty acid oxidation reactions.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CYP505E3 | Self-sufficient omega-7 in-chain hydroxylase acting on fatty acids | Model enzyme for fungal in-chain hydroxylation and biocatalysis |
| CYP505E subfamily members | Fungal self-sufficient in-chain hydroxylating P450 monooxygenases | Subfamily delineation and functional assignment |
| Plant laurate in-chain hydroxylase | Microsomal P450 that hydroxylates lauric acid at an internal carbon | Early biochemical model for plant in-chain hydroxylation [5, 8] |
| CYP94C1 | Arabidopsis P450 catalyzing dicarboxylic fatty acid formation in vitro | Links in-chain oxidation to fatty acid catabolism |
| CYP3A1 | P450 that catalyzes in-chain desaturation of valproic acid | Drug metabolism relevance of fatty acid oxidation |
| CYP267B1 | Myxobacterial P450 oxidizing medium-chain fatty acids | Structural insights into substrate handling |
| CYP505E3 reductase domain | Fused diflavin reductase that transfers electrons from NADPH | Explains self-sufficient catalysis [1, 3] |
| CYP505E3 P450 domain | Heme-containing domain that binds fatty acid and activates oxygen | Catalytic core for in-chain hydroxylation |
| CYP94C1 heme domain | P450 catalytic domain for dicarboxylic fatty acid formation | Mechanistic studies of plant fatty acid oxidation |
| CYP3A1 heme domain | P450 catalytic domain for valproic acid desaturation | Isoform selectivity studies |
| CYP267B1 heme domain | P450 catalytic domain for medium-chain fatty acid oxidation | Structural and mechanistic analysis |
| Plant microsomal P450 system | Membrane-bound enzyme system for laurate in-chain hydroxylation | Induction and specificity studies |
| NADPH-cytochrome P450 reductase | Redox partner for microsomal P450 enzymes | Electron transfer in plant and mammalian systems |
| Lauric acid | Model substrate for in-chain hydroxylase assays | Substrate specificity and enzyme kinetics [5, 8] |
| Valproic acid | Drug substrate for P450-mediated in-chain desaturation | Pharmacological relevance |
| Medium-chain fatty acids | Substrates for myxobacterial CYP267B1 | Structure-function studies |
| Dicarboxylic fatty acids | Downstream products of in-chain oxidation | Plant lipid catabolism |
How Is fatty acid in-chain hydroxylase activity Regulated?
Fatty acid in-chain hydroxylase activity is regulated at multiple levels. In plants, the laurate in-chain hydroxylase from Helianthus tuberosus microsomes is inducible, and its activity can be selectively inactivated by unsaturated substrate analogs, indicating tight control of enzyme levels and active-site chemistry [5, 8]. Arabidopsis CYP94C1 is responsive to methyl jasmonate and wounding, linking expression of an in-chain oxidizing P450 to stress and developmental signals. In fungi, the self-sufficient CYP505E enzymes are regulated by their fused reductase domain, which controls electron supply from NADPH and thus catalytic turnover [1, 3]. At the protein level, P450 enzymes can undergo autocatalytic inactivation, as shown for plant lauric acid in-chain hydroxylase, providing a feedback mechanism that limits excessive activity. Together, these mechanisms tune in-chain hydroxylation to substrate availability, redox status and cellular signals [2, 4].
fatty acid in-chain hydroxylase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CYP3A1 | Valproic acid metabolism and drug response | Hepatocyte cell lines with CYP3A1 knockout or overexpression |
| CYP94C1 | Fatty acid catabolism and dicarboxylic acid formation | Plant or heterologous cell models with CYP94C1 knockout |
| CYP505E3 | Fungal lipid metabolism and biocatalysis | Fungal knockout and knock-in strains [1, 3] |
| Plant laurate in-chain hydroxylase | Plant stress and wound responses | Plant microsomal assays and mutant lines [5, 8] |
| CYP267B1 | Medium-chain fatty acid oxidation | Bacterial expression and structural models |
Fatty acid oxidation and drug metabolism
P450-catalyzed in-chain oxidation of fatty acids is mechanistically related to drug metabolism, as illustrated by CYP3A1-mediated in-chain desaturation of valproic acid to Delta-3-valproic acid. This connection is important because valproic acid is a widely used anticonvulsant, and its metabolic transformation can influence efficacy and toxicity. Understanding GO:0052722 therefore helps interpret inter-individual differences in fatty acid and drug oxidation [2, 6].
Lipid catabolism and metabolic disorders
In-chain hydroxylation can initiate the formation of dicarboxylic fatty acids, which are products of fatty acid catabolism and are relevant to disorders of lipid metabolism. Arabidopsis CYP94C1 catalyzes dicarboxylic fatty acid formation in vitro, providing a plant model for how in-chain oxidation feeds into lipid breakdown pathways. Dysregulation of such pathways in humans could affect energy homeostasis and lipid accumulation, although direct disease links for GO:0052722 remain an active area of research [2, 4].
Microbial and fungal P450s in infection and biotechnology
Fungal CYP505E enzymes are self-sufficient in-chain hydroxylases that may contribute to fungal lipid remodeling and host interaction [1, 3]. Because these enzymes are structurally distinct and can be heterologously expressed, they are also candidates for antifungal target discovery and for biocatalytic production of hydroxy fatty acids [1, 3]. Studying their activity in cell models can clarify roles in fungal physiology and potential virulence.
From fatty acid in-chain hydroxylase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of an in-chain hydroxylase alter fatty acid profiles? | CRISPR knockout cell line or fungal strain [1, 3] |
| Which residue controls regioselectivity? | Point-mutation knock-in of active-site variants |
| Can a tagged enzyme be tracked in cells? | Knock-in of an epitope-tagged P450 |
| Does overexpression increase hydroxy fatty acid production? | Overexpression cell model or microbial host [1, 3] |
| How does a disease-associated variant affect catalysis? | Point-mutation cell model with enzyme assays |
| Can in-chain hydroxylation be redirected to a new substrate? | Directed evolution and knock-in libraries [3, 7] |
How to Study the fatty acid in-chain hydroxylase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Microsomal enzyme assay | In-chain hydroxylase activity with NADPH and fatty acid | Plant and mammalian P450 characterization [5, 8] |
| Recombinant expression | Activity of a single P450 enzyme | Fungal CYP505E3 functional analysis |
| LC-MS or GC-MS | Hydroxy fatty acid products and regiochemistry | Product identification [1, 7] |
| X-ray crystallography | Three-dimensional structure of P450 with substrate | Active-site and regioselectivity studies |
| Site-directed mutagenesis | Effect of specific residues on catalysis | Mechanistic dissection |
| Heterologous cell assays | Cellular fatty acid oxidation and product formation | CYP94C1 and CYP3A1 studies [4, 6] |
| Genome mining | Identification of new in-chain hydroxylase candidates | CYP505E subfamily discovery |
| CRISPR knockout | Loss-of-function phenotype for a candidate gene | Linking gene to fatty acid profile [1, 3] |
Enzyme activity assays
In vitro assays using microsomes or purified P450 enzymes with fatty acid substrates and NADPH are the primary way to measure GO:0052722. Plant laurate in-chain hydroxylase activity was characterized in microsomal fractions, and substrate specificity was defined using lauric acid and analogs [5, 8]. For self-sufficient CYP505E3, activity can be measured without an added reductase because the enzyme contains its own redox domain. Product analysis by chromatography or mass spectrometry confirms the position of the hydroxy group [1, 7].
Structural and mechanistic studies
X-ray crystallography and site-directed mutagenesis reveal how P450 enzymes position fatty acids for in-chain hydroxylation. Structural insights into CYP267B1 showed how medium-chain fatty acids bind and are oxidized. Similar approaches can identify the residues that distinguish in-chain hydroxylation from terminal hydroxylation or desaturation [1, 7]. These studies are essential for interpreting GO:0052722 annotations and for engineering new specificities.
Heterologous expression and cell-based assays
Expressing P450 enzymes in heterologous hosts allows functional testing of candidate genes. CYP505E3 was characterized as a novel self-sufficient in-chain hydroxylase using recombinant expression. Arabidopsis CYP94C1 was expressed and assayed in vitro to demonstrate dicarboxylic fatty acid formation. Cell-based assays with knockout or overexpression can link enzyme activity to lipid profiles and stress responses [4, 6].
Genome mining and bioinformatics
Bioinformatic analysis of P450 sequences can identify new in-chain hydroxylases. Delineation of the CYP505E subfamily used sequence and functional data to define a group of fungal self-sufficient in-chain hydroxylating enzymes. Comparative genomics and phylogenetic analysis help predict substrate specificity and guide experimental validation [3, 7]. These methods are increasingly used to annotate GO:0052722 in newly sequenced genomes.
How CRISPR Can Be Used to Study GO:0052722 fatty acid in-chain hydroxylase activity
Knockout
CRISPR knockout of a candidate in-chain hydroxylase gene removes the enzyme and allows researchers to test whether the corresponding fatty acid oxidation product disappears. This is useful for validating GO:0052722 annotations in fungal, plant or mammalian cells [1, 3]. Knockout models can also reveal compensatory pathways and substrate accumulation.
Point Mutation
Point mutations in the P450 active site can switch regioselectivity or abolish catalysis. CRISPR-mediated point mutation of residues identified by structural studies, such as those in CYP267B1, allows direct testing of their role in in-chain hydroxylation. This approach helps distinguish in-chain hydroxylation from terminal hydroxylation or desaturation [1, 7].
Knock-in
Knock-in of an epitope tag or fluorescent protein at the endogenous locus enables tracking of the enzyme in its native context. Tagged knock-in of a self-sufficient P450 such as CYP505E3 can be used to monitor expression, localization and turnover. Knock-in of disease-associated variants can also model altered fatty acid metabolism.
Overexpression
Overexpression of an in-chain hydroxylase can increase production of hydroxy fatty acids and reveal downstream effects on lipid metabolism. This is particularly useful for biocatalysis and for testing whether increased activity alters cell physiology [1, 3]. Overexpression models complement knockout studies by providing gain-of-function evidence.
How EDITGENE Supports fatty acid in-chain hydroxylase activity Research
Researchers studying fatty acid in-chain hydroxylase activity-related genes often need to determine whether a candidate gene is causally involved in fatty acid oxidation, how specific residues control regioselectivity, and whether altered expression changes lipid phenotypes. EDITGENE provides CRISPR-based cell models and screening services to address these questions with reproducible, publication-ready reagents.
Contact EDITGENE today to design your custom CRISPR model for fatty acid in-chain hydroxylase activity research.
Frequently Asked Questions About fatty acid in-chain hydroxylase activity
What is fatty acid in-chain hydroxylase activity?
It is the enzyme activity defined by GO:0052722 that catalyzes the reaction fatty acid + O2 + 2 NADPH + H+ = fatty acid with in-chain hydroxy group + 2 NADP+ + H2O, inserting a hydroxy group at an internal carbon of a fatty acid [1, 2].
What genes are involved in fatty acid in-chain hydroxylase activity?
Genes encoding cytochrome P450 enzymes such as CYP505E3, plant laurate in-chain hydroxylase, CYP94C1, CYP3A1 and CYP267B1 are involved in or closely related to this activity [1, 3, 4, 6, 7].
Which enzyme is a self-sufficient in-chain hydroxylase?
CYP505E3 is a fungal self-sufficient omega-7 in-chain hydroxylase that contains both a P450 domain and a fused reductase domain [1, 3].
What is the difference between in-chain hydroxylation and terminal hydroxylation?
In-chain hydroxylation adds a hydroxy group to an internal carbon, whereas terminal hydroxylation modifies the omega carbon; the position is determined by active-site geometry [1, 7].
How is fatty acid in-chain hydroxylase activity measured?
It is typically measured using microsomal or recombinant enzyme assays with fatty acid substrates and NADPH, followed by product analysis by chromatography or mass spectrometry [1, 5, 8].
Is fatty acid in-chain hydroxylase activity related to drug metabolism?
Yes, P450 enzymes can catalyze in-chain desaturation of drugs such as valproic acid, linking this activity to drug metabolism.
What is the role of CYP94C1 in fatty acid oxidation?
CYP94C1 from Arabidopsis catalyzes dicarboxylic fatty acid formation in vitro, connecting in-chain oxidation to fatty acid catabolism.
Can CRISPR be used to study fatty acid in-chain hydroxylase activity?
Yes, CRISPR knockout, point mutation, knock-in and overexpression models can test the function of candidate P450 genes in cells [1, 3, 7].
Which substrates are used to assay in-chain hydroxylases?
Lauric acid is a classic substrate for plant laurate in-chain hydroxylase, while medium-chain fatty acids and valproic acid are used for other P450 enzymes [5, 6, 7, 8].
Why is GO:0052722 important for biotechnology?
Self-sufficient in-chain hydroxylases such as CYP505E3 can produce hydroxy fatty acids, which are valuable building blocks for chemicals and pharmaceuticals [1, 3].
Conclusion
GO:0052722, fatty acid in-chain hydroxylase activity, defines a specific P450-dependent oxidation that inserts a hydroxy group at an internal fatty acid carbon. The reaction is catalyzed by diverse enzymes, from plant microsomal laurate in-chain hydroxylase to fungal self-sufficient CYP505E3 and bacterial CYP267B1, and it connects to dicarboxylic acid formation and drug metabolism [1, 3, 4, 6, 7]. Understanding its mechanism, regulation and cellular roles provides a foundation for metabolic engineering and disease research [2, 5, 8]. CRISPR-based cell models, combined with enzyme assays, structural biology and bioinformatics, offer a robust path to validate gene function and explore therapeutic or biotechnological applications of in-chain hydroxylation [1, 3, 7].
References
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- 2. Salaün JP et al.. 1995. Cytochrome P450-dependent oxidation of fatty acids.. Drug Metabol Drug Interact 12(3-4):261-83 PMID: 8820856
- 3. Smit MS et al.. 2023. Delineation of the CYP505E subfamily of fungal self-sufficient in-chain hydroxylating cytochrome P450 monooxygenases.. Appl Microbiol Biotechnol 107(2-3):735-747 PMID: 36607403
- 4. Kandel S et al.. 2007. Characterization of a methyl jasmonate and wounding-responsive cytochrome P450 of Arabidopsis thaliana catalyzing dicarboxylic fatty acid formation in vitro.. FEBS J 274(19):5116-27 PMID: 17868380
- 5. Salaun JP et al.. 1984. Autocatalytic inactivation of plant cytochrome P-450 enzymes: selective inactivation of the lauric acid in-chain hydroxylase from Helianthus tuberosus L. by unsaturated substrate analogs.. Arch Biochem Biophys 232(1):1-7 PMID: 6742847
- 6. Fisher MB et al.. 1998. P450-catalyzed in-chain desaturation of valproic acid: isoform selectivity and mechanism of formation of Delta 3-valproic acid generated by baculovirus-expressed CYP3A1.. Arch Biochem Biophys 356(1):63-70 PMID: 9681992
- 7. Jóźwik IK et al.. 2018. Structural insights into oxidation of medium-chain fatty acids and flavanone by myxobacterial cytochrome P450 CYP267B1.. Biochem J 475(17):2801-2817 PMID: 30045877
- 8. Salaün JP et al.. 1981. Induction and specificity of a (cytochrome P-450)-dependent laurate in-chain-hydroxylase from higher plant microsomes.. Eur J Biochem 119(3):651-5 PMID: 7308207
