Recombinant Pisum sativum Photosystem II reaction center protein H (psbH)
Description
2.1. Membrane Topology
PsbH is an intrinsic membrane protein with:
Electron microscopy studies localize the N-terminus near the stromal surface of PSII, adjacent to the CP47 subunit .
2.2. Functional Insights
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QB Site Regulation: PsbH stabilizes the QB-binding pocket on the D1 protein, influencing electron transfer from QA to QB .
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Photoinhibition Resistance: Deletion or mutation of PsbH reduces tolerance to high-light stress by destabilizing PSII dynamics .
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CP47 Accumulation: In Arabidopsis, PsbH is required for stable accumulation of the CP47 reaction center protein .
3.1. Expression and Isolation
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Fusion Strategy: PsbH is expressed as a glutathione-S-transferase (GST) fusion protein in E. coli to enhance solubility .
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Cleavage and Purification: GST tag removal via Factor Xa protease yields ~2.1 µg/mL of pure PsbH .
3.2. Biophysical Characterization
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Secondary Structure: Circular dichroism (CD) spectroscopy confirms α-helical content (37%) matching transmembrane predictions .
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NMR Analysis: 1H-15N HSQC spectra in β-D-octyl-glucopyranoside detergent reveal stable folding .
4.1. Antibody Development
Polyclonal antibodies against PsbH (e.g., Agrisera AS06 157) detect 4–7.7 kDa bands in plant extracts, aiding PSII assembly studies .
4.2. Mutagenesis Studies
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Synechocystis Mutants: Truncations in PsbH’s N-terminus reduce charge recombination rates by 50%, indicating altered PSII core flexibility .
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Nuclear Complementation: Nuclear-encoded PsbH rescues PSII defects in Arabidopsis hcf107 mutants, restoring photoautotrophy .
Comparative Analysis of PsbH Across Species
| Feature | P. sativum | Cyanobacteria | Arabidopsis |
|---|---|---|---|
| Phosphorylation | Absent | Absent | Present (Thr residues) |
| Gene Location | Plastid genome | Plastid genome | Nuclear genome |
| Molecular Weight | 7.7 kDa | 7.0–9.9 kDa | 7.7 kDa |
Key Research Findings
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Light Stress Adaptation: PsbH-deficient PSII shows accelerated photodamage due to impaired QB site stability .
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CP47 Dependency: PsbH knockout reduces CP47 levels by 50%, suggesting structural interdependence .
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Evolutionary Conservation: PsbH’s transmembrane helix is conserved across oxygenic phototrophs, underscoring its functional essentiality .
Product Specs
Note: We will prioritize shipping the format we have in stock. However, if you have a specific format requirement, please indicate it when placing your order, and we will fulfill your request.
Note: All our proteins are shipped with standard blue ice packs. If you require dry ice shipping, please inform us in advance, as additional fees will 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.
