Recombinant Candida tropicalis V-type proton ATPase catalytic subunit A (VMA1)
Description
Overview of V-Type Proton ATPase Catalytic Subunit A (VMA1)
Vacuolar-type ATPases (V-ATPases) are conserved proton pumps critical for pH regulation in eukaryotic cells. The catalytic subunit A (VMA1) forms part of the V domain, which hydrolyzes ATP to drive proton translocation across membranes . In Candida tropicalis, VMA1 is encoded by the VMA1 gene and plays essential roles in organelle acidification, nutrient sensing, and virulence . Recombinant VMA1 refers to the subunit produced via heterologous expression systems (e.g., Kluyveromyces lactis), enabling biochemical and structural studies .
Recombinant Production and Challenges
Expression systems:
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Kluyveromyces lactis: Used for high-yield production of C. tropicalis proteins (e.g., CtPra1) .
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Saccharomyces cerevisiae: Common for fungal V-ATPase studies but requires intein removal for functional VMA1 .
Key challenges:
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Intein splicing: The C. tropicalis VMA1 intein necessitates precise excision for proper folding. Inefficient splicing reduces functional yields .
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Post-translational modifications: Glycosylation and phosphorylation may affect activity but are host-dependent .
Functional Roles in C. tropicalis Physiology
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Vacuolar acidification: VMA1 enables proton transport into vacuoles (pH ~5.8), crucial for protease activation and metal detoxification .
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Virulence modulation:
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Stress adaptation: Maintains cytosolic pH under oxidative or osmotic stress .
Research Applications and Findings
Biochemical studies:
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ATPase activity: Recombinant VMA1 exhibits concanamycin A-sensitive ATP hydrolysis (~90% loss in vph1 mutants) .
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Proton transport: Assayed using purified vacuolar membranes, showing a stoichiometry of 2 H/ATP .
Pathogenesis insights:
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Mouse models: C. tropicalis VMA1 mutants show attenuated virulence in systemic infections due to defective organ colonization .
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Immune evasion: VMA1-linked pH regulation may affect complement protein binding (e.g., factor H, C4BP) .
