Recombinant Protein traH (traH)
Description
Definition and Biological Role
TraH is a VirB8-like protein encoded by conjugative plasmids such as pIP501 in Enterococcus faecalis. It is indispensable for T4SS-mediated DNA transfer, a process critical for disseminating antibiotic resistance genes . TraH interacts with multiple proteins to regulate pilus dynamics (extension/retraction) and stabilize the secretion machinery .
Recombinant Production
TraH is produced using recombinant DNA technology in heterologous hosts like Escherichia coli or Saccharomyces cerevisiae:
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Expression Systems:
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Purification: Affinity tags (e.g., His-tag) enable efficient isolation via nickel-chelate chromatography .
Functional Mechanisms
TraH orchestrates conjugation through protein-protein interactions and oligomerization:
Key Interactions
| Interacting Protein | TraH Binding Region | Functional Impact |
|---|---|---|
| TrbI | Residues 193–225 | Regulates pilus retraction |
| TraF | Residues 315–458 | Stabilizes pilus structure |
| TraU | Residues 341–458 | Modulates pilus length |
Oligomerization
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TraH forms dimers to tetramers in micelles, a property critical for membrane channel assembly .
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Deletion of traH abolishes plasmid transfer, underscoring its non-redundant role in T4SS .
Essentiality in Conjugation
| Strain | Transfer Frequency (Transconjugants/Recipient) |
|---|---|
| Wild-type pIP501 | 2.3 × 10⁻⁵ |
| pIP501ΔtraH | <2.3 × 10⁻⁸ (undetectable) |
| pIP501ΔtraH + traH | 2.3 × 10⁻⁵ (full rescue) |
Source: Biparental mating assays in E. faecalis
Applications in Research
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Antibiotic Resistance Studies: TraH is a target for inhibiting plasmid-mediated gene transfer .
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Structural Biology: NMR and crystallography studies of TraH inform T4SS engineering .
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Drug Development: Screening TraH inhibitors could curb multidrug-resistant pathogen spread .
