title: The open reading frame III product of cauliflower mosaic virus forms a tetramer through a N-terminal coiled-coil.
abstract: The open reading frame III product of cauliflower mosaic virus is a protein of 15 kDa (p15) that is essential for the virus life cycle. It was shown that the 34 N-terminal amino acids are sufficient to support protein-protein interaction with the full-length p15 in the yeast two-hybrid system. A corresponding peptide was synthesized and a recombinant p15 was expressed in Escherichia coli and purified. Circular dichroism spectroscopy showed that the peptide and the full-length protein can assume an alpha-helical conformation. Analytical centrifugation allowed to determine that p15 assembles as a rod-shaped tetramer. Oxidative cross-linking of N-terminal cysteines of the peptide generated specific covalent oligomers, indicating that the N terminus of p15 is a coiled-coil that assembles as a parallel tetramer. Mutation of Lys22 into Asp destabilized the tetramer and put forward the presence of a salt bridge between Lys22 and Asp24 in a model building of the stalk. These results suggest a model in which the stalk segment of p15 is located at its N terminus, followed by a hinge that provides the space for presenting the C terminus for interactions with nucleic acids and/or proteins.
authors.affiliation: Friedrich Miescher Institut, P. O. Box 2543, CH-4002 Basel, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Leclerc
authors.forename: L
authors.initials: L
authors.lastname: Burri
authors.forename: A V
authors.initials: AV
authors.lastname: Kajava
authors.forename: J L
authors.initials: JL
authors.lastname: Mougeot
authors.forename: D
authors.initials: D
authors.lastname: Hess
authors.forename: A
authors.initials: A
authors.lastname: Lustig
authors.forename: G
authors.initials: G
authors.lastname: Kleemann
authors.forename: T
authors.initials: T
authors.lastname: Hohn
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001704:Biopolymers; D017796:Caulimovirus / Q000737:chemistry*; D002850:Chromatography, Gel; D017931:DNA Primers; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016366:Open Reading Frames; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055672:Static Electricity; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001704:Biopolymers; D017931:DNA Primers; D011994:Recombinant Proteins; D014764:Viral Proteins; C115486:p15 protein, Cauliflower mosaic virus