title: Tacaribe virus Z protein interacts with the L polymerase protein to inhibit viral RNA synthesis.
abstract: Tacaribe virus (TV) is the prototype of the New World group of arenaviruses. The TV genome encodes four proteins, the nucleoprotein (N), the glycoprotein precursor, the polymerase (L), and a small RING finger protein (Z). Using a reverse genetic system, we recently demonstrated that TV N and L are sufficient to drive transcription and full-cycle RNA replication mediated by TV-like RNAs and that Z is a powerful inhibitor of these processes (N. López, R. Jácamo, and M. T. Franze-Fernández, J. Virol. 65:12241-12251, 2001). In the present study we investigated whether Z might interact with either of the proteins, N and L, required for RNA synthesis. To that end, we used coimmunoprecipitation with monospecific antibodies against the viral proteins and coimmunoprecipitation with serum against glutathione S-transferase (GST) and binding to glutathione-Sepharose beads when Z was expressed as a fusion protein with GST. We demonstrated that Z interacted with L but not with N and that Z inhibitory activity was dependent on its ability to bind to L. We also evaluated the contribution of different Z regions to its binding ability and functional activity. We found that integrity of the RING structure is essential for Z binding to L and for Z inhibitory activity. Mutants with deletions at the N and C termini of Z showed that amino acids within the C-terminal region and immediately adjacent to the RING domain N terminus contribute to efficient Z-L interaction and are required for inhibitory activity. The data presented here provide the first evidence of an interaction between Z and L, suggesting that Z interferes with viral RNA synthesis by direct interaction with L. In addition, coimmunoprecipitation studies revealed a previously unreported interaction between N and L.
authors.affiliation: Centro de Virología Animal (CONICET), C1414DEM Buenos Aires, Argentina.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Jácamo
authors.forename: Nora
authors.initials: N
authors.lastname: López
authors.forename: Maximiliano
authors.initials: M
authors.lastname: Wilda
authors.forename: María T
authors.initials: MT
authors.lastname: Franze-Fernández
mesh_terms: D006477:Arenaviruses, New World / Q000235:genetics*; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000502:physiology*; D012321:DNA-Directed RNA Polymerases / Q000502:physiology*; D019590:Nucleocapsid Proteins / Q000502:physiology; D011233:Precipitin Tests; D012367:RNA, Viral / Q000096:biosynthesis*; D014764:Viral Proteins / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D019590:Nucleocapsid Proteins; D012367:RNA, Viral; D014764:Viral Proteins; C079186:Z protein, Tacaribe virus; D012321:DNA-Directed RNA Polymerases