Molecular determinants of Arenavirus Z protein homo-oligomerization and L polymerase binding

LOUREIRO, E; WILDA, M; LEVINGSTON, J; D'ANTUONO, A; FOSACALDI, S; MARINO BUSLJE, CRISTINA; LOPEZ, N

Buenso Aires

Workshop; 3rd ICGEB WORKSHOP ON HUMAN RNA VIRUSES; 2012

Instituto Leloir

The arenavirus Z is a zinc-binding RING protein implicated in multiple functions. Z inhibits viral RNA transcription and replication through direct interaction with the viral L polymerase. Here, we defined the L-binding domain within Tacaribe virus (TCRV) Z protein and the structural requirements mediating Z homo-oligomerization. By using site-directed mutagenesis, IP and functional assays, we showed that residues located around the zinc-coordination site I, play a critical role in Z-L interaction and found that Z protein from either TCRV or the pathogenic Junin virus (JUNV), self-associates into oligomeric forms in mammalian cells. Mutation of the Z myristoylation site (the strictly conserved residue G at position 2), severely impaired the ability of both TCRV Z and JUNV Z to self-interact and accumulate at the plasma membrane, strongly suggesting that Z homo-oligomerization is associated to cell membrane targeting. In contrast, disruption of the RING domain or substitution of  aa critical for L protein recognition, did not affect Z self-binding. Overall,  homo-oligomerization is not a requirement for Z-L interaction and Z-mediated polymerase activity inhibition