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PLoS Pathog. 2015 Apr 13;11(4):e1004826. doi: 10.1371/journal.ppat.1004826. eCollection 2015 Apr.

Phosphorylation at the homotypic interface regulates nucleoprotein oligomerization and assembly of the influenza virus replication machinery.

Author information

1
Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, United States of America.
2
Department of Chemistry, University of Wisconsin, Madison, Wisconsin, United States of America.
3
Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, United States of America; Cellular and Molecular Biology Graduate Program, University of Wisconsin, Madison, Wisconsin, United States of America.
4
Department of Chemistry, University of Wisconsin, Madison, Wisconsin, United States of America; Department of Biomolecular Chemistry, University of Wisconsin, Madison, Wisconsin, United States of America.

Abstract

Negative-sense RNA viruses assemble large ribonucleoprotein (RNP) complexes that direct replication and transcription of the viral genome. Influenza virus RNPs contain the polymerase, genomic RNA and multiple copies of nucleoprotein (NP). During RNP assembly, monomeric NP oligomerizes along the length of the genomic RNA. Regulated assembly of the RNP is essential for virus replication, but how NP is maintained as a monomer that subsequently oligomerizes to form RNPs is poorly understood. Here we elucidate a mechanism whereby NP phosphorylation regulates oligomerization. We identified new evolutionarily conserved phosphorylation sites on NP and demonstrated that phosphorylation of NP decreased formation of higher-order complexes. Two phosphorylation sites were located on opposite sides of the NP:NP interface. In both influenza A and B virus, mutating or mimicking phosphorylation at these residues blocked homotypic interactions and drove NP towards a monomeric form. Highlighting the central role of this process during infection, these mutations impaired RNP formation, polymerase activity and virus replication. Thus, dynamic phosphorylation of NP regulates RNP assembly and modulates progression through the viral life cycle.

PMID:
25867750
PMCID:
PMC4395114
DOI:
10.1371/journal.ppat.1004826
[Indexed for MEDLINE]
Free PMC Article

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