Purification and biochemical characterization of a monomeric form of papaya mosaic potexvirus coat protein

Protein Expr Purif. 2006 May;47(1):273-80. doi: 10.1016/j.pep.2005.10.013. Epub 2005 Nov 4.

Abstract

Papaya mosaic virus (PapMV) is a flexuous rod shape virus made of 1400 subunits that assemble around a plus sense genomic RNA. The structure determination of PapMV and of flexuous viruses in general is a major challenge for both NMR and X-ray crystallography. In this report, we present the characterization of a truncated version of the PapMV coat protein (CP) that is suitable for NMR study. The deletion of the N-terminal 26 amino acids of the PapMV CP (CP27-215) generates a monomer that can be expressed to high level and easily purified for production of an adequate NMR sample. The RNA gel shift assay showed that CP27-215 lost its ability to bind RNA in vitro, suggesting that the multimerization of the subunit is important for this function. The fusion of a 6x His tag at the C-terminus improved the solubility of the monomer and allowed its concentration to 0.2 mM. The CD spectra of the truncated and the wild-type proteins were similar, suggesting that both proteins are well ordered and have a similar secondary structure. CP27-215 was 15N labeled for NMR studies and a 2D 1H-15N-HSQC spectrum confirmed the presence of a well-ordered structure and the monomeric form of the protein. These results show that CP27-215 is amenable to a complete and exhaustive NMR study that should lead to the first three-dimensional structure determination of a flexuous rod shape virus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Capsid Proteins / chemistry*
  • Capsid Proteins / genetics
  • Capsid Proteins / isolation & purification*
  • Carica / virology*
  • Cloning, Molecular
  • Escherichia coli
  • Molecular Sequence Data
  • Potexvirus / chemistry*
  • Potexvirus / genetics

Substances

  • Capsid Proteins