title: Mutation of capsid protein phosphorylation sites abolishes cauliflower mosaic virus infectivity.
abstract: The cauliflower mosaic virus (CaMV) capsid protein is derived by bidirectional processing of the precapsid protein (CP56). We expressed several derivatives of CP56 in Escherichia coli and used them as substrates for virus-associated kinase and casein kinase II purified from plant cells. Three serine residues located at the N terminus of the mature viral protein CP44 were identified as phosphorylation targets. A mutation of one of them in the viral context had little or no effect on viral infectivity, but a mutation of all three serines abolished infectivity. The mapping of phosphorylation sites in CP44, but not CP39 or CP37, and immunodetection of the Zn finger motif in CP44 and CP39, but not CP37, support the model that CP39 is produced from CP44 by N-terminal processing and CP37 is produced from CP39 by C-terminal processing. We discuss the possible role of phosphorylation in the processing and assembly of CaMV capsid protein.
authors.affiliation: Friedrich-Miescher Institute, CH-4002 Basel, Switzerland.
authors.forename: Yvan
authors.initials: Y
authors.lastname: Chapdelaine
authors.forename: David
authors.initials: D
authors.lastname: Kirk
authors.forename: Aletta
authors.initials: A
authors.lastname: Karsies
authors.forename: Thomas
authors.initials: T
authors.lastname: Hohn
authors.forename: Denis
authors.initials: D
authors.lastname: Leclerc
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis; D002213:Capsid / Q000737:chemistry / Q000378:metabolism*; D047390:Casein Kinase II; D017796:Caulimovirus / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D011498:Protein Precursors; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases