Recombinant Sesamum indicum Cytochrome c
Description
Contextual Overview of Cytochrome Systems in Sesamum indicum
Sesame produces specialized cytochrome P450 enzymes critical for synthesizing lignans like sesamin. Key systems include:
Table 1: Key Cytochrome Enzymes in Sesamum indicum
These enzymes require redox partners like CPR1 for electron transfer, analogous to cytochrome c’s role in mitochondrial electron transport .
Cloning and Expression
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CYP81Q1: Cloned from developing sesame seeds (stage 4) using cDNA synthesis. Expressed in E. coli BL21(DE3) with a yield of 4.8 mg/L. Purified via His-tag affinity chromatography, confirmed by SDS-PAGE (55 kDa band) .
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CPR1: Co-expressed with CYP81Q1 in E. coli, yielding 3.9 mg/L. Critical for enhancing CYP81Q1 activity by 3–4× in sesamin synthesis .
Functional Characterization
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Activity Assay: HPLC confirmed CYP81Q1’s ability to convert pinoresinol to sesamin. Activity increased from 12% (CYP81Q1 alone) to 95% when paired with CPR1 and NADPH .
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Structural Insights: CYP81Q1 contains a conserved heme-binding domain (AGHTSG) essential for catalytic activity .
Comparative Analysis of Cytochrome c Production Systems
While no studies describe S. indicum cytochrome c, bacterial systems for recombinant cytochrome c biogenesis provide methodological parallels:
Table 2: Recombinant Cytochrome Production Systems
| System | Host | Yield | Key Features | Reference |
|---|---|---|---|---|
| CcmABCDEFGH | E. coli | 2–5 mg/L | System I pathway for heme attachment | |
| CYP81Q1/CPR1 | E. coli | 4.8 mg/L | Requires NADPH and CPR1 for activity |
The Ccm system in E. coli enables holocytochrome c production via heme ligation, a process absent in native sesame cytochrome studies .
Challenges and Opportunities
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Heterologous Compatibility: Sesame cytochrome P450s (e.g., CYP81Q1) require eukaryotic post-translational modifications, limiting activity in prokaryotic systems .
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Electron Transport Coupling: Functional coordination between CYP81Q1 and CPR1 mirrors cytochrome c’s interaction with Complex III/IV, suggesting conserved redox mechanisms .
Future Directions
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Structural Studies: Crystallization of CYP81Q1-CPR1 complexes to elucidate electron transfer mechanisms.
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Metabolic Engineering: Co-expression of sesame cytochrome P450s with bacterial Ccm systems to synthesize chimeric redox proteins.
