Recombinant Escherichia coli O81 ATP synthase subunit c (atpE)
Description
Recombinant Escherichia coli O81 ATP Synthase Subunit c (atpE): Overview
The recombinant E. coli O81 ATP synthase subunit c (atpE) is a full-length transmembrane protein (1–79 amino acids) critical for proton-driven ATP synthesis. This protein is part of the F₀ sector of the F₁F₀ ATP synthase complex, which couples proton translocation across bacterial membranes to ATP production . Expressed in E. coli with an N-terminal His-tag, it is purified to >90% purity via SDS-PAGE and stored in lyophilized form with Tris/PBS-based buffer and 6% trehalose .
Functional Role in ATP Synthesis
Subunit c interacts with subunit a to form a proton-translocation pathway. Mutagenesis studies revealed that residues A217, I221, and L224 on subunit a’s fourth helix coordinate with subunit c’s helix to stabilize proton movement . In E. coli, this ATP synthase requires a higher proton motive force (∆ψ) threshold (~150 mV) compared to other organisms, such as Acetobacterium woodii (~90 mV) .
Proton Translocation Mechanism
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Subunit a–c Interaction: Cysteine substitutions in subunits a (helix 4) and c (helix 2) enabled disulfide bridge formation, confirming direct physical interactions critical for proton translocation .
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Threshold Energetics: E. coli ATP synthase with subunit c requires both ∆ψ and ∆pH for ATP synthesis, unlike A. woodii, which can utilize ∆ψ alone .
Recombinant Production
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Expression System: Expressed in E. coli via optimized codon usage and His-tagging for affinity purification .
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Purity and Stability: >90% purity confirmed via SDS-PAGE; repeated freeze-thaw cycles are discouraged .
Comparative Analysis with Other ATP Synthases
| Organism | Subunit c Type | Ion Translocated | ATP Synthesis Threshold |
|---|---|---|---|
| E. coli | Single hairpin | H⁺ | 150 mV |
| P. modestum | Single hairpin | Na⁺ | 120 mV |
| A. woodii | Hybrid (V-type + single hairpin) | Na⁺ | 90 mV |
Data highlight E. coli’s higher energy requirement for ATP synthesis, linked to its H⁺-dependent mechanism .
Product Specs
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Target Background
KEGG: ecq:ECED1_4427
