title: The F13 residue is critical for interaction among the coat protein subunits of papaya mosaic virus.
abstract: Papaya mosaic virus (PapMV) coat protein (CP) in Escherichia coli was previously showed to self-assemble in nucleocapsid-like particles (NLPs) that were similar in shape and appearance to the native virus. We have also shown that a truncated CP missing the N-terminal 26 amino acids is monomeric and loses its ability to bind RNA. It is likely that the N-terminus of the CP is important for the interaction between the subunits in self-assembly into NLPs. In this work, through deletion and mutation analysis, we have shown that the deletion of 13 amino acids is sufficient to generate the monomeric form of the CP. Furthermore, we have shown that residue F13 is critical for self-assembly of the CP subunits into NLPs. The replacement of F13 with hydrophobic residues (L or Y) generated mutated forms of the CP that were able to self-assemble into NLPs. However, the replacement of F13 by A, G, R, E or S was detrimental to the self-assembly of the protein into NLPs. We concluded that a hydrophobic interaction at the N-terminus is important to ensure self-assembly of the protein into NLPs. We also discuss the importance of F13 for assembly of other members of the potexvirus family.
authors.affiliation:  Infectious Disease Research Centre, Laval University, Québec, Canada.
authors.forename: M E
authors.initials: ME
authors.lastname: Laliberté Gagné
authors.affiliation:  Department of Biochemistry, Laval University, Québec, Canada.
authors.forename: K
authors.initials: K
authors.lastname: Lecours
authors.affiliation:  Department of Biochemistry, Laval University, Québec, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Gagné
authors.affiliation:  Infectious Disease Research Centre, Laval University, Québec, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Leclerc
mesh_terms: D000595:Amino Acid Sequence; D036022:Capsid Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D029441:Carica / Q000821:virology*; D002850:Chromatography, Gel; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D019251:Nucleocapsid / Q000737:chemistry / Q000378:metabolism; D010649:Phenylalanine / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D017863:Potexvirus / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D036022:Capsid Proteins; D021122:Protein Subunits; C529259:coat protein, papaya mosiac virus; D010649:Phenylalanine