Recombinant Podospora anserina 3-ketoacyl-CoA reductase (Pa_6_6580)
Description
Introduction to 3-ketoacyl-CoA Reductase
3-ketoacyl-CoA reductase (KAR) represents a key enzyme in the metabolic pathway of fatty acids, specifically catalyzing the reduction of 3-ketoacyl-CoA to 3-hydroxyacyl-CoA during fatty acid synthesis and β-oxidation processes. The enzyme from Podospora anserina, a filamentous ascomycete fungus, is of particular interest to researchers studying comparative biochemistry and fungal metabolism. This enzyme, also referred to as 3-ketoreductase or microsomal beta-keto-reductase, has been assigned the Enzyme Commission (EC) number 1.1.1.-, indicating its role as an oxidoreductase acting on the CH-OH group of donors with NAD+ or NADP+ as an acceptor .
Podospora anserina has been established as a valuable model organism in mycology and cellular biology research, particularly for investigations into aging, mitochondrial function, and metabolic processes. The study of its metabolic enzymes, including 3-ketoacyl-CoA reductase, provides insights into fundamental biochemical processes that may be applicable across various species. The availability of recombinant forms of this enzyme facilitates detailed biochemical characterization and functional studies.
Protein Information and Classification
Recombinant Podospora anserina 3-ketoacyl-CoA reductase is encoded by the gene designated as Pa_6_6580. This protein has been cataloged in the UniProt database with the accession number B2B3L4, providing a reference point for researchers . The enzyme belongs to the short-chain dehydrogenase/reductase (SDR) superfamily, which is characterized by specific sequence motifs and a conserved Rossmann fold for nucleotide binding.
Table 1: Molecular Characteristics of Recombinant Podospora anserina 3-ketoacyl-CoA Reductase
| Characteristic | Description |
|---|---|
| Protein Name | 3-ketoacyl-CoA reductase |
| Alternative Names | 3-ketoreductase, KAR, Microsomal beta-keto-reductase |
| Organism | Podospora anserina (strain S / ATCC MYA-4624 / DSM 980 / FGSC 10383) |
| Gene Identifier | Pa_6_6580 |
| UniProt Accession | B2B3L4 |
| EC Number | 1.1.1.- |
| Protein Length | 340 amino acids |
| Expression Region | 1-340 |
Enzymatic Reaction
The primary function of 3-ketoacyl-CoA reductase is to catalyze the reduction of a ketone group at the C-3 position of a fatty acyl-CoA molecule, converting 3-ketoacyl-CoA to 3-hydroxyacyl-CoA. This reaction requires the cofactor NADPH (or in some cases NADH), which donates a hydride ion to the carbonyl carbon, resulting in the formation of a hydroxyl group . The general reaction can be represented as:
3-ketoacyl-CoA + NAD(P)H + H+ → 3-hydroxyacyl-CoA + NAD(P)+
Induced Fit Model in Enzymatic Catalysis
The catalytic mechanism of enzymes like 3-ketoacyl-CoA reductase follows the induced fit model of enzyme catalysis. In this model, the binding of the substrate to the enzyme induces conformational changes in both molecules, bringing them into optimal alignment for the reaction to occur . The process typically follows these stages:
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The enzyme and substrate exist initially as separate entities
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The enzyme and substrate bind to form an initial complex
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Both the enzyme and substrate undergo conformational changes, resulting in a tight binding at the transition state
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The reaction occurs, converting the substrate to product
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The enzyme releases the product and returns to its original conformation
In the case of 3-ketoacyl-CoA reductase, this induced fit mechanism ensures precise positioning of the 3-ketoacyl-CoA substrate and the NAD(P)H cofactor, facilitating efficient hydride transfer and subsequent reduction of the ketone group.
Role in Fatty Acid Metabolism
In the context of fatty acid metabolism, 3-ketoacyl-CoA reductase plays different roles depending on the metabolic pathway. In fatty acid synthesis, it contributes to the elongation of fatty acid chains by reducing the ketone group formed during the condensation reaction. In β-oxidation, it participates in the catabolic breakdown of fatty acids for energy production.
Recent research on the ascomycete yeast Candida lusitaniae has revealed that fatty acid β-oxidation can occur in both peroxisomes and mitochondria, challenging the traditional view that ascomycete yeasts possess only a peroxisome-localized β-oxidation pathway . The study demonstrated that a key enzyme in this pathway, Fox2p, is localized to both organelles. While this finding pertains specifically to C. lusitaniae, it raises interesting questions about the potential dual localization of similar enzymes like 3-ketoacyl-CoA reductase in related fungi such as Podospora anserina.
Table 2: Enzymatic Properties of 3-ketoacyl-CoA Reductases (Comparative Analysis)
| Property | Podospora anserina | Ascomycete Yeasts | Mammals |
|---|---|---|---|
| Cofactor Preference | NADPH (predicted) | NADPH | NADPH |
| Subcellular Localization | Predicted: Peroxisomal | Peroxisomal/Mitochondrial* | Mitochondrial/Endoplasmic reticulum |
| Role in β-Oxidation | Fatty acid degradation | Fatty acid degradation | Fatty acid degradation |
| Role in Fatty Acid Synthesis | Fatty acid elongation | Fatty acid elongation | Fatty acid elongation |
*Based on studies in Candida lusitaniae
Expression and Purification
The recombinant production of Podospora anserina 3-ketoacyl-CoA reductase involves expression of the Pa_6_6580 gene in a suitable host system, followed by purification steps to isolate the protein. While specific details of the expression system used for commercial production are not provided in the available search results, common approaches for recombinant protein production include bacterial (E. coli), yeast (Saccharomyces cerevisiae, Pichia pastoris), or mammalian cell culture systems .
The purification of recombinant proteins typically involves multiple chromatographic steps, which may include affinity chromatography (utilizing fusion tags), ion exchange chromatography, and size exclusion chromatography. These processes aim to isolate the target protein with high purity while maintaining its native structure and enzymatic activity.
Enzyme Assays and Kinetic Studies
The availability of purified recombinant enzyme enables detailed kinetic studies to characterize its catalytic properties. Parameters such as Km (Michaelis constant), kcat (turnover number), and substrate specificity can be determined through carefully designed enzyme assays. This information contributes to the broader understanding of enzyme function and can guide the development of applications in biotechnology and medicine.
Comparative Biochemistry and Evolution
Comparative studies of 3-ketoacyl-CoA reductases from different organisms can reveal evolutionary relationships and adaptations in fatty acid metabolism. The Podospora anserina enzyme, representing filamentous fungi, can be compared with homologs from yeasts, bacteria, plants, and animals to identify conserved features and lineage-specific adaptations .
Table 4: Applications of Recombinant Podospora anserina 3-ketoacyl-CoA Reductase
| Application | Description | Potential Benefits |
|---|---|---|
| Enzyme Kinetics Studies | Investigation of catalytic mechanism and kinetic parameters | Understanding of fungal metabolism |
| Structural Biology | Determination of three-dimensional structure | Insights into substrate binding and catalysis |
| Inhibitor Screening | Identification of compounds that modulate enzyme activity | Potential antifungal drug development |
| Antibody Production | Generation of antibodies against the enzyme | Tools for localization and expression studies |
| Metabolic Engineering | Modification of fatty acid metabolism pathways | Enhanced production of valuable lipids |
| Comparative Biochemistry | Analysis of evolutionary relationships among similar enzymes | Understanding of metabolic adaptation |
Expression Challenges
The production of recombinant full-length proteins like Podospora anserina 3-ketoacyl-CoA reductase often faces various challenges. These can include issues related to protein hydrophobicity, codon usage, and potential toxicity to the host expression system . Proteins with highly hydrophobic regions, such as membrane-associated enzymes, may be particularly difficult to express in soluble form. Additionally, differences in codon usage between the source organism (Podospora anserina) and the expression host can impact translation efficiency and protein yield.
Ensuring Protein Functionality
A critical aspect of recombinant protein production is ensuring that the expressed protein maintains its native structure and enzymatic activity. This can be particularly challenging for enzymes that require specific cofactors, post-translational modifications, or protein-protein interactions for optimal function. Various strategies, such as co-expression with chaperones, optimization of expression conditions, and careful design of purification protocols, may be employed to address these challenges.
Future Perspectives and Research Directions
The study of recombinant Podospora anserina 3-ketoacyl-CoA reductase opens several avenues for future research. These include detailed characterization of its enzymatic properties, investigation of its regulation in response to environmental conditions, exploration of its potential applications in biotechnology, and comparative studies with homologous enzymes from other organisms.
With the advancement of protein structure prediction technologies such as AlphaFold2, there are enhanced opportunities for understanding the structural basis of enzyme function even in the absence of experimental structures . These computational approaches, combined with experimental biochemical studies, can provide comprehensive insights into the molecular mechanisms underlying fatty acid metabolism in fungi and other organisms.
Product Specs
Note: We will prioritize shipping the format currently in stock. However, if you have specific format requirements, please indicate them in your order notes. We will accommodate your request to the best of our ability.
Note: Our proteins are shipped standard with normal blue ice packs. If you require dry ice shipping, please inform us in advance. Additional fees may apply.
Generally, the shelf life of the liquid form is 6 months at -20°C/-80°C. The shelf life of the lyophilized form is 12 months at -20°C/-80°C.
Target Background
KEGG: pan:PODANSg7603
STRING: 515849.XP_001910564.1
Q&A
What is 3-ketoacyl-CoA reductase and what is its role in Podospora anserina?
3-ketoacyl-CoA reductase (also known as 3-ketoreductase, KAR, or Microsomal beta-keto-reductase) is an enzyme involved in fatty acid biosynthesis. In Podospora anserina, this enzyme (Pa_6_6580) plays a critical role in metabolic pathways related to lipid metabolism. The protein has EC designation 1.1.1.- and functions within mitochondrial metabolic networks that influence the organism's aging process. Podospora anserina serves as a model organism where mitochondrial function has been repeatedly demonstrated to control aging processes . The enzyme's activity may indirectly affect free radical generation rates in mitochondria, potentially influencing lifespan control mechanisms that have been documented in this filamentous fungus.
What are the optimal storage conditions for maintaining recombinant Pa_6_6580 activity?
For effective storage of recombinant Pa_6_6580, the following protocol is recommended:
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Store the protein in a Tris-based buffer supplemented with 50% glycerol
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For short-term storage (up to one week), maintain working aliquots at 4°C
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For standard storage, keep at -20°C
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For extended preservation, store at -20°C or preferably -80°C
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Avoid repeated freeze-thaw cycles as they can compromise protein integrity and activity
For experiments requiring precise enzymatic activity measurements, it's advisable to prepare single-use aliquots during initial protein processing to minimize activity loss from multiple freeze-thaw cycles.
How can researchers effectively measure 3-ketoacyl-CoA reductase activity in experimental systems?
Measuring 3-ketoacyl-CoA reductase activity requires monitoring the reduction of 3-ketoacyl-CoA substrates to 3-hydroxyacyl-CoA using NAD(P)H as a cofactor. A methodological approach involves:
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Spectrophotometric assay: Monitor the oxidation of NADPH at 340 nm in a reaction mixture containing:
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Purified recombinant Pa_6_6580
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3-ketoacyl-CoA substrate (varying concentrations for kinetic studies)
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NADPH (typically 0.1-0.2 mM)
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Buffer system (usually phosphate or Tris-based, pH 7.0-7.5)
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HPLC-based product detection: For more sensitive measurements, especially in complex biological samples
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Extract reaction products using organic solvents
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Analyze by HPLC with appropriate detection methods
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Kinetic analysis: For determining enzyme parameters such as Km and Vmax, using software like KinTek Explorer for dynamic computer simulation of enzyme kinetics
These methodologies can be adapted for different experimental questions, from basic activity verification to complex mechanistic studies of substrate specificity.
How does Pa_6_6580 contribute to mitochondrial function and aging research in P. anserina?
P. anserina has been established as a model organism for studying aging, with strong evidence supporting the central role of mitochondria in lifespan determination. Research integration of Pa_6_6580 can address:
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Metabolic pathway analysis: 3-ketoacyl-CoA reductase functions in fatty acid metabolism, potentially influencing membrane composition and mitochondrial function
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Free radical generation: Studies have demonstrated that alterations in electron transport chain components affect mitochondrial free radical generation, correlating with lifespan extension . Researchers can investigate whether Pa_6_6580 activity influences:
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Reactive oxygen species (ROS) production
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Mitochondrial membrane composition
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Interaction with electron transport chain components
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Comparative analysis: Examining differences in enzyme activity between wild-type strains and long-lived mutants (e.g., grisea mutant) can reveal correlations between metabolic alterations and lifespan extension
Methodology for these investigations typically employs isolated mitochondria, measurement of superoxide generation rates, oxygen consumption analysis, and assessment of membrane fatty acid composition to establish mechanistic links between enzyme activity and aging phenotypes.
What experimental approaches can be used to investigate interactions between Pa_6_6580 and other mitochondrial proteins?
To investigate protein-protein interactions involving Pa_6_6580, researchers can employ several complementary approaches:
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Co-immunoprecipitation (Co-IP):
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Express tagged versions of Pa_6_6580 in P. anserina
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Precipitate using tag-specific antibodies
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Identify interacting partners through mass spectrometry
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Proximity-based labeling:
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Generate fusion proteins with BioID or APEX2
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Identify proteins in close proximity through biotinylation
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Analyze biotinylated proteins by mass spectrometry
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Yeast two-hybrid screening:
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Use Pa_6_6580 as bait to screen for interacting partners
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Validate interactions through secondary assays
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Functional correlation studies:
These approaches should be combined with control experiments and validation through multiple methods to establish reliable interaction networks.
How might Pa_6_6580 function relate to the allorecognition system in Podospora anserina?
Podospora anserina employs an allorecognition system termed heterokaryon or vegetative incompatibility, controlled by nine incompatibility loci (het loci) . While direct evidence linking Pa_6_6580 to this system is not established in the available literature, researchers might consider:
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Metabolic influence hypothesis: Changes in lipid metabolism through 3-ketoacyl-CoA reductase activity could potentially affect membrane properties relevant to cell fusion and recognition processes
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Experimental approaches to investigate potential relationships:
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Compare Pa_6_6580 expression and activity between compatible and incompatible strains
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Generate knockout or overexpression strains to observe effects on vegetative incompatibility
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Investigate potential metabolic interactions with het loci products, particularly the recently characterized het-B locus components Bh and Bp
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Regulatory network analysis:
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Perform transcriptomic analysis to identify potential co-regulation patterns between Pa_6_6580 and het loci
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Investigate whether regulated cell death (RCD) triggered during incompatibility affects Pa_6_6580 expression or activity
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This represents an unexplored area where metabolic enzymes like Pa_6_6580 might indirectly influence or be influenced by allorecognition processes.
What approaches can be used to investigate the role of Pa_6_6580 in mitochondrial free radical generation and lifespan control?
Investigation of Pa_6_6580's role in free radical generation requires sophisticated methodological approaches:
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Genetic manipulation strategies:
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Generate knockout strains (ΔPa_6_6580)
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Create point-mutant variants with altered activity
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Develop overexpression strains
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Mitochondrial free radical measurement:
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Respiratory chain analysis:
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Lifespan studies:
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Conduct chronological and replicative lifespan assays
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Correlate lifespan changes with alterations in mitochondrial metabolism
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Analyze survival curves under various environmental conditions
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This integrative approach can establish causal relationships between enzyme activity, free radical generation, and aging phenotypes in P. anserina.
What are the critical factors affecting the activity and stability of recombinant Pa_6_6580 in experimental systems?
Several factors can significantly impact the activity and stability of recombinant Pa_6_6580:
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Buffer composition:
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Temperature considerations:
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Cofactor requirements:
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NADPH concentration can be rate-limiting
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NADPH:NADH preference should be established for optimal activity
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Reducing agents:
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May be required to prevent oxidation of catalytic cysteine residues
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Common options include DTT or β-mercaptoethanol at 1-5 mM
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Metal ion effects:
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Enzyme activity may be affected by divalent cations
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EDTA or metal supplementation might be necessary depending on specific requirements
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Researchers should systematically optimize these parameters for their specific experimental systems to ensure reproducible and meaningful results.
How can researchers distinguish between activity of recombinant Pa_6_6580 and endogenous reductases in complex biological samples?
When working with complex biological samples, distinguishing recombinant Pa_6_6580 activity from endogenous reductases requires specific methodological approaches:
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Immunological methods:
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Develop specific antibodies against Pa_6_6580
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Use immunodepletion to remove endogenous enzyme
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Employ immunoprecipitation to isolate specific enzyme complexes
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Affinity tag utilization:
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Express recombinant Pa_6_6580 with affinity tags
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Perform activity assays before and after tag-based purification
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Compare kinetic parameters with those of endogenous enzymes
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Inhibitor profiles:
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Establish differential inhibitor sensitivity profiles
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Use specific inhibitors to selectively block endogenous activities
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Develop selective activity assays based on inhibitor responses
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Substrate specificity:
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Identify unique substrate preferences for Pa_6_6580
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Design assays using these specific substrates
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Compare activity patterns across different substrate types
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Genetic approaches in model systems:
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Generate knockout backgrounds lacking endogenous reductases
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Compare activity profiles between wild-type and knockout backgrounds
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Use complementation studies to confirm specific activity contributions
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These approaches can be combined to create robust experimental systems for accurately measuring Pa_6_6580 activity in complex samples.
