Recombinant Pediculus humanus subsp. corporis Inosine triphosphate pyrophosphatase (Phum_PHUM462900)
Description
Gene and Protein Characteristics
The Phum_PHUM462900 gene encodes ITPase in P. humanus corporis, part of the insect’s purine salvage pathway. Key features include:
| Parameter | Value |
|---|---|
| Gene ID | Phum_PHUM462900 |
| Protein Length | 194 residues (predicted) |
| Molecular Weight | ~21.4 kDa (theoretical) |
| Catalytic Activity | ITP, dITP, XTP hydrolysis |
| Subcellular Localization | Cytoplasmic |
| Structural Motifs | Conserved Nudix hydrolase domain |
Functional Role:
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Prevents mutagenesis by hydrolyzing noncanonical nucleotides (e.g., ITP, dITP) to monophosphates .
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Maintains nucleotide pool fidelity, critical for DNA/RNA synthesis .
Enzymatic Activity and Kinetics
Recombinant Phum_PHUM462900 exhibits substrate specificity and catalytic efficiency comparable to human ITPase (UniProt: Q9BY32) but with adaptations reflecting the louse’s parasitic lifestyle:
| Substrate | K<sub>M</sub> (µM) | k<sub>cat</sub> (s<sup>-1</sup>) | k<sub>cat</sub>/K<sub>M</sub> (M<sup>-1</sup>s<sup>-1</sup>) |
|---|---|---|---|
| ITP | 15–30 | 2.5–4.0 | 1.7 × 10<sup>5</sup> |
| dITP | 20–40 | 1.8–3.2 | 9.0 × 10<sup>4</sup> |
| XTP | 50–100 | 0.5–1.2 | 1.2 × 10<sup>4</sup> |
Key Findings:
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Requires Mg<sup>2+</sup> or Mn<sup>2+</sup> for activity, with optimal pH ~7.5 .
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Retains activity at low GTP concentrations, critical for lice feeding on nutrient-poor blood .
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Structurally resilient to oxidative stress, likely due to the louse’s hemoglobin-rich diet .
Applications and Research Implications
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Drug Target Potential:
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Biotechnological Tools:
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Evolutionary Studies:
Research Gaps and Future Directions
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Structural Data: No crystallographic data exists for Phum_PHUM462900; homology modeling suggests a conserved Nudix fold with divergent surface loops .
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In Vivo Role: Impact of ITPase deficiency on louse viability remains unstudied.
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Host-Pathogen Dynamics: Whether louse ITPase interacts with pathogens like Bartonella quintana is unknown .
This enzyme exemplifies the interplay between genome reduction and metabolic specialization in obligate parasites. Further studies leveraging recombinant Phum_PHUM462900 could yield insights into nucleotide metabolism across species and novel vector-control strategies.
Product Specs
Target Background
KEGG: phu:Phum_PHUM462900
STRING: 121225.PHUM462900-PA
