title: Interactions and nuclear import of the N and P proteins of sonchus yellow net virus, a plant nucleorhabdovirus.
abstract: We have characterized the interaction and nuclear localization of the nucleocapsid (N) protein and phosphoprotein (P) of sonchus yellow net nucleorhabdovirus. Expression studies with plant and yeast cells revealed that both N and P are capable of independent nuclear import. Site-specific mutagenesis and deletion analyses demonstrated that N contains a carboxy-terminal bipartite nuclear localization signal (NLS) located between amino acids 465 and 481 and that P contains a karyophillic region between amino acids 40 and 124. The N NLS was fully capable of functioning outside of the context of the N protein and was able to direct the nuclear import of a synthetic protein fusion consisting of green fluorescent protein fused to glutathione S-transferase (GST). Expression and mapping studies suggested that the karyophillic domain in P is located within the N-binding domain. Coexpression of N and P drastically affected their localization patterns relative to those of individually expressed proteins and resulted in a shift of both proteins to a subnuclear region. Yeast two-hybrid and GST pulldown experiments verified the N-P and P-P interactions, and deletion analyses have identified the N and P interacting domains. N NLS mutants were not transported to the nucleus by import-competent P, presumably because N binding masks the P NLS. Taken together, our results support a model for independent entry of N and P into the nucleus followed by associations that mediate subnuclear localization.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, 94720, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Goodin
authors.forename: J
authors.initials: J
authors.lastname: Austin
authors.forename: R
authors.initials: R
authors.lastname: Tobias
authors.forename: M
authors.initials: M
authors.lastname: Fujita
authors.forename: C
authors.initials: C
authors.lastname: Morales
authors.forename: A O
authors.initials: AO
authors.lastname: Jackson
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism / Q000821:virology; D019590:Nucleocapsid Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010944:Plants / Q000821:virology*; D011485:Protein Binding; D021381:Protein Transport; D012209:Rhabdoviridae / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D019590:Nucleocapsid Proteins; D010750:Phosphoproteins