Expression and purification of dynamin II domains and initial studies on structure and function

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Dynamin II is a large GTP-binding protein crucial for endocytosis and vesicle formation at the trans-Golgi network.
• Understanding the specific functions of dynamin II domains requires purified, active protein fragments.

Purpose of the Study:

• To express and purify functional domains of dynamin II, including the pleckstrin homology domain (PHD), proline-rich domain (PRD), and C-terminal region (dynamin(500-870)).
• To develop methods for isolating these domains in sufficient quantity and purity for further functional studies.

Main Methods:

• Expression of dynamin II domains (PHD, PRD, dynamin(500-870)) in Escherichia coli with various affinity tags ((His)(6) and S-peptide).
• Purification using nickel-chelating agarose and immobilized S-protein affinity chromatography.
• Characterization of protein structure using circular dichroism (CD) spectroscopy.
• Assessment of protein-protein interactions using binding assays with SH3 domains and rat brain extracts.

Main Results:

• Recombinant PHD was expressed to 15% of cellular protein and purified, showing structured secondary content similar to dynamin I PHD.
• Recombinant PRD, though unfolded, specifically bound to the SH3 domain of amphiphysin II and rat brain proteins.
• Optimized N-terminal and C-terminal tagging strategies facilitated purification and removal of contaminants.

Conclusions:

• The study successfully developed methods for isolating functionally active PHD and PRD of dynamin II.
• These purified domains are suitable for detailed biochemical and structural analyses to elucidate dynamin II function in endocytosis.