The RING domain and the residue L79 of the Z protein are involved in both the rescue of nucleocapsids and the incorporation of glycoproteins into infectious chimeric arenavirus-like particles

CASABONA, JUAN CRUZ; LEVINGSTON MAC LEOD, JESICA; LOUREIRO, MARIA EUGENIA; GOMEZ, GUILLERMO; LOPEZ, NORA

JOURNAL OF VIROLOGY

American Society for Microbiology

Lugar: Washington DC; Año: 2009 vol. 83 p. 7029 - 7039

0022-538X

Arenaviruses, such as Tacaribe virus (TacV) and its closely related pathogenic Junin virus (JunV), are enveloped viruses with a bipartite negative-sense RNA genome that encodes the nucleocapsid protein (N), the precursor of the envelope glycoprotein complex (GP), the polymerase (L), and a RING finger protein (Z), which is the driving force of arenavirus budding. We have established a plasmid-based system which allowed the successful packaging of TacV-like nucleocapsids along with Z and GP of JunV into infectious virus-like particles (VLPs). By coexpressing different combinations of the system components, followed by biochemicalanalysis of the VLPs, the requirements for the assembly of both N and GP into particles were defined. We found that coexpression of N with Z protein in the absence of minigenome and other viral proteins was sufficient to recruit N within lipid-enveloped Z-containing VLPs. In addition,  whereas GP was not required for the incorporation of N, coexpression of N substantially enhanced the ratio of GP to Z into VLPs. Disruption of the RING structure or mutation of  residue L79 to alanine within Z protein, although it had no effect on Z self-budding, severely impaired VLP infectivity. These mutations drastically altered intracellular Z-N interactions and the incorporation of both N and GP into VLPs. Our results support the conclusion that the interaction between Z and N is required for assembly of both the nucleocapsids and the glycoproteins into infectious arenavirus budding particles.