A N-terminal coiled coil motif is essential for Tacaribe virus Nucleoprotein functionality

D'ANTUONO A; LEVINGSTON J; LOUREIRO E; LÓPEZ N

Chubut - Argentina

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Arenaviruses, such as Tacaribe virus (TCRV) are enveloped viruses with a negative-sense RNA genome, which encodes four proteins: the viral RNA polymerase (L protein), a matrix protein (Z), the precursor (GPC) of the envelope glycoproteins and the nucleocapsid protein (N). The N protein tightly binds to genomic and antigenomic RNAs forming nucleocapsids, which act as templates for both transcription and replication of viral genomes mediated by the virus polymerase. Besides, the ability of N to take part in multiple protein-protein interactions may be important in several steps of the viral life cycle. We have shown that the N-terminal region of N is responsible for homotypic N-N interactions. Here, we have defined a newly recognized coiled coil motif domain as being essential for N self-interactions. Key hydrophobic amino acids within the putative coiled coil motif, were replaced by the polar amino acid Glutamine. The ability of point mutants to self-interact was evaluated by coimmunoprecipitation and their capacity to support viral RNA synthesis was assessed using a TCRV minireplicon system. The relevance of the coiled coil motif in the interaction between N and the L polymerase will be discussed. It is concluded that residues 92-119 of the TCRV N protein may fold as a coiled coil, which is crucial for N to sustain N-N interactions as well as for its role in viral genome replication.