Recombinant Escherichia coli ATP synthase subunit beta (atpD)
Description
Functional Role in ATP Synthase Mechanism
AtpD is integral to the "binding change mechanism," where conformational changes in β-subunits drive ATP synthesis/hydrolysis. Key findings include:
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Catalytic activity: Engineered AtpD retains 15–20% of wild-type ATPase activity, attributed to steric effects of tags .
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Rotation coupling: Biotin-tagged AtpD rotates counterclockwise during ATP hydrolysis, generating torque equivalent to wild-type γ-subunit rotation (≈40 pN·nm) .
Table 2: Functional Comparison of Recombinant vs. Wild-Type AtpD
Applications in Biomedical Research
Recombinant AtpD has been leveraged in multiple studies:
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Serological assays: Mycoplasma pneumoniae AtpD (homologous to E. coli AtpD) was expressed in E. coli and used to detect early-stage infections, demonstrating cross-reactivity and diagnostic potential .
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Structural studies: Tagged AtpD enabled visualization of subunit rotation via actin filament microscopy .
Interactions with Antimicrobial Agents
While not directly targeting AtpD, studies on antimicrobial peptides (e.g., EcDBS1R4) reveal indirect effects on ATP synthase:
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Membrane-mediated inhibition: EcDBS1R4 reduces ATPase activity by 20% in E. coli inner membrane vesicles, likely via cardiolipin sequestration near F₀ subunits .
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Lipid dependency: Inhibition requires cardiolipin-rich membranes, highlighting the β-subunit’s reliance on membrane integrity .
Engineering Challenges and Solutions
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Expression issues: Recombinant AtpD expression in E. coli DK8 (Δunc) yields reduced ATPase activity due to lower enzyme abundance .
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Functional rescue: Co-expression with other F₀F₁ subunits restores partial oxidative phosphorylation capacity .
Future Directions
Product Specs
Target Background
KEGG: ecy:ECSE_4022
