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Updated: Aug 25, 2026
Protein Membrane Overlay Assay: A Protocol to Test Interaction Between Soluble and Insoluble Proteins in vitro
Published on: August 14, 2011
Dimerization of recombinant tobacco mosaic virus movement protein
Laurence M Brill1, Songpon Dechongkit, Byron DeLaBarre
1Department of Cell Biology, The Scripps Research Institute, Scripps Clinic, La Jolla, California 92037, USA.
Abstract:
The p30 movement protein (MP) is essential for cell-to-cell spread of tobacco mosaic virus in planta. We used anion-exchange chromatography and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to obtain highly purified 30-kDa MP, which migrated as a single band in native PAGE. Analytical ultracentrifugation suggested that the protein was monodisperse and dimeric in the nonionic detergent n-octyl-beta-D-glucopyranoside. Circular dichroism (CD) spectroscopy showed that the detergent-solubilized protein contained significant alpha-helical secondary structure. Proteolysis of the C-tail generated a trypsin-resistant core that was a mixture of primarily monomers and some dimers. We propose that MP dimers are stabilized by electrostatic interactions in the C terminus as well as hydrophobic interactions between putative transmembrane alpha-helical coiled coils.
Insights
The p30 movement protein (MP) is crucial for tobacco mosaic virus spread. Purified MP exists as dimers stabilized by C-terminal electrostatic and hydrophobic interactions, forming alpha-helical coiled coils.
Area of Science:
- Plant virology
- Protein biochemistry
- Molecular biology
Background:
- The p30 movement protein (MP) is essential for the cell-to-cell movement of tobacco mosaic virus (TMV) within host plants.
- Understanding MP structure and interactions is key to deciphering viral spread mechanisms.
Purpose of the Study:
- To purify and characterize the structural properties of the TMV p30 movement protein.
- To investigate the oligomeric state and secondary structure of MP.
- To explore the role of the C-terminus in MP dimerization.
Main Methods:
- Anion-exchange chromatography and preparative SDS-PAGE for protein purification.
- Native PAGE and analytical ultracentrifugation to determine oligomeric state.
- Circular dichroism (CD) spectroscopy to analyze secondary structure.
- Limited proteolysis to identify stable protein domains.
Main Results:
- Highly purified 30-kDa MP was obtained, appearing as a single band in native PAGE.
- Analytical ultracentrifugation indicated MP is monodisperse and dimeric in detergent.
- CD spectroscopy revealed significant alpha-helical content in detergent-solubilized MP.
- Proteolysis generated a trypsin-resistant core, predominantly monomers with some dimers.
Conclusions:
- TMV p30 MP exists as dimers in solution, stabilized by both electrostatic interactions in the C-terminus and hydrophobic interactions.
- The protein possesses substantial alpha-helical secondary structure.
- MP dimerization is likely mediated by transmembrane alpha-helical coiled-coil structures.
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