Metallothioneins for correlative light and electron microscopy

Area of Science:

• Structural biology
• Cell biology
• Microscopy

Background:

• Identifying proteins within cells is crucial for understanding biological processes.
• Existing methods for protein detection in electron microscopy have limitations.

Purpose of the Study:

• To explore the use of metallothionein (MT) as a tag for unambiguous protein detection in transmission electron microscopy.
• To demonstrate the sensitivity and applicability of MT-gold tagging for visualizing intracellular proteins.

Main Methods:

• Fusing metallothionein (MT) to proteins of interest.
• Treating cells with gold salts to form electron-dense clusters on MT tags.
• Utilizing transmission electron microscopy for visualization.
• Employing immunogold labeling for specificity confirmation.
• Applying direct correlative light and electron microscopy for dual-resolution imaging.

Main Results:

• Metallothionein (MT) tags successfully formed ~1 nm electron-dense gold clusters when treated with gold salts.
• MT-gold tagging allowed sensitive and specific detection of intracellular proteins in bacteria and eukaryotic cells.
• Correlative microscopy visualized macromolecular complexes at different spatial resolutions.
• The method is compatible with various sample processing techniques.

Conclusions:

• Metallothionein (MT)-gold tagging is a sensitive and specific method for detecting intracellular proteins via transmission electron microscopy.
• This technique aids in visualizing protein distribution and macromolecular complexes.
• Further development is needed for multi-labeling and compatibility with advanced cryo-electron microscopy techniques.