Humanized archaeal ferritin as a tool for cell targeted delivery

Area of Science:

• Biotechnology
• Nanotechnology
• Structural Biology

Background:

• Human ferritins are promising nanocarriers for drug delivery but require acidic conditions for assembly, potentially compromising cargo stability.
• This limitation hinders their application in targeted anticancer drug and imaging agent delivery.

Purpose of the Study:

• To engineer a chimeric ferritin protein that overcomes the acidic pH requirement for assembly.
• To create a nanocarrier that maintains Archaeoglobus fulgidus ferritin's assembly properties at neutral pH while enabling human cell recognition.

Main Methods:

• Genetic engineering of Archaeoglobus fulgidus ferritin by modifying a surface-exposed loop to mimic human H-chain ferritin.
• Characterization of the chimeric protein's assembly properties at neutral pH.
• Assessment of transferrin receptor (TfR1) recognition and cellular uptake by HeLa cells.
• Determination of the three-dimensional structure using X-ray diffraction and cryo-electron microscopy (cryo-EM).

Main Results:

• The chimeric ferritin protein self-assembles at neutral pH, retaining the cation-linked association-dissociation properties of Archaeoglobus fulgidus ferritin.
• The engineered protein effectively binds to the human transferrin receptor (TfR1) via the modified loop.
• HeLa cells actively and specifically internalized the chimeric ferritin, demonstrating its potential for targeted delivery.
• The 12-amino acid loop was identified as both necessary and sufficient for TfR1 binding.

Conclusions:

• The humanized Archaeoglobus ferritin represents a novel nanotechnological tool for cell-targeted delivery of diagnostic or therapeutic payloads.
• This engineered ferritin overcomes the pH limitations of native human ferritins, enabling applications under physiological conditions.
• The structural and functional characterization provides a foundation for developing advanced ferritin-based nanomedicines.