title: Newly identified minor phosphorylation site threonine-279 of measles virus nucleoprotein is a prerequisite for nucleocapsid formation.
abstract: Measles virus nucleoprotein is the most abundant viral protein and tightly encapsidates viral genomic RNA to support viral transcription and replication. Major phosphorylation sites of nucleoprotein include the serine residues at locations 479 and 510. Minor phosphorylation residues have yet to be identified, and their functions are poorly understood. In our present study, we identified nine putative phosphorylation sites by mass spectrometry and demonstrated that threonine residue 279 (T279) is functionally significant. Minigenome expression assays revealed that a mutation at the T279 site caused a loss of activity. Limited proteolysis and electron microscopy suggested that a T279A mutant lacked the ability to encapsidate viral RNA but was not denatured. Furthermore, dephosphorylation of the T279 site by alkaline phosphatase treatment caused deficiencies in nucleocapsid formation. Taken together, these results indicate that phosphorylation at T279 is a prerequisite for successful nucleocapsid formation.
authors.affiliation: International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Sugai
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sato
authors.forename: Kyoji
authors.initials: K
authors.lastname: Hagiwara
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kozuka-Hata
authors.forename: Masaaki
authors.initials: M
authors.lastname: Oyama
authors.forename: Misako
authors.initials: M
authors.lastname: Yoneda
authors.forename: Chieko
authors.initials: C
authors.lastname: Kai
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002460:Cell Line; D006801:Humans; D008457:Measles / Q000821:virology*; D008459:Measles virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D019251:Nucleocapsid / Q000235:genetics / Q000378:metabolism*; D019590:Nucleocapsid Proteins; D009698:Nucleoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D013912:Threonine / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D019590:Nucleocapsid Proteins; D009698:Nucleoproteins; D014764:Viral Proteins; C058314:nucleoprotein, Measles virus; D013912:Threonine