The Rift Valley fever virus nonstructural protein NSs is phosphorylated at serine residues located in casein kinase II consensus motifs in the carboxy-terminus.
The S segment of Rift Valley fever virus (Bunyaviridae, Phlebovirus) codes for two proteins, the nucleoprotein N and the nonstructural protein NSs. The NSs protein is a phosphoprotein of unknown function that is localized in the cytoplasm and the nuclei of infected cells where it forms filamentous structures. To characterize further the protein expressed in VC10 cells infected with the MP12 strain, we analyzed its phosphorylation states and showed that phosphorylated forms were found in both compartments. Cytoplasmic and nuclear NSs were phosphorylated only at serine residues. Phosphopeptide mapping and molecular analysis of mutants obtained by site-directed mutagenesis allowed us to map the major phosphorylation sites of nuclear and cytoplasmic forms of NSs to serine residues 252 and 256, located at the carboxy-terminus in consensus sequences for casein kinase II. A similar map was obtained when the protein was purified from mosquito cells infected with MP12. In addition, we showed that the purified unphosphorylated NSs protein expressed from pET-NSs plasmid in a coupled transcription-translation reaction containing Escherichia coli S30 extracts did not possess autophosphorylation activity but was phosphorylated in vitro after incubation with recombinant casein kinase II.
Kohl
A
A
Unité des Arbovirus et Virus des Fièvres Hémorragiques, Unité d'Immunologie Moléculaire, Institut Pasteur, 25 Rue du Dr Roux, Paris, 75724, France.
di Bartolo
V
V
Bouloy
M
M
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D047390:Casein Kinase II; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D016384:Consensus Sequence / Q000235:genetics*; D009033:Culicidae / Q000166:cytology / Q000821:virology; D003488:Cyanogen Bromide / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010449:Peptide Mapping; D010766:Phosphorylation; D010768:Phosphoserine / Q000032:analysis / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012296:Rift Valley fever virus / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000235:genetics / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D011993:Recombinant Fusion Proteins; D017361:Viral Nonstructural Proteins; D010768:Phosphoserine; D012694:Serine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D003488:Cyanogen Bromide