Arenavirus Z-Glycoprotein Association Requires Z Myristoylation but Not Functional RING or Late Domains

Abstract

Generation of infectious arenavirus-like particles requires the virus RING finger Z protein and surface glycoprotein precursor (GPC) and the correct processing of GPC into GP1, GP2, and a stable signal peptide (SSP). Z is the driving force of arenavirus budding, whereas the GP complex (GPc), consisting of hetero-oligomers of SSP, GP1, and GP2, forms the viral envelope spikes that mediate receptor recognition and cell entry. Based on the roles played by Z and GP in the arenavirus life cycle, we hypothesized that Z and the GPc should interact in a manner required for virion formation. Here, using confocal microscopy and coimmunoprecipitation assays, we provide evidence for subcellular colocalization and biochemical interaction, respectively, of Z and the GPc. Our results from mutation-function analysis reveal that Z myristoylation, but not the Z late (L) or RING domain, is required for Z-GPc interaction. Moreover, Z interacted directly with SSP in the absence of other components of the GPc. We obtained similar results with Z and GPC from the prototypical arenavirus lymphocytic choriomeningitis virus and the hemorrhagic fever arenavirus Lassa fever virus.

Arenavirus Z protein controls viral RNA synthesis by locking a polymerase–promoter complex

“…1 E and F). Z has been identified as a binding partner to both host and viral proteins (15)(16)(17)(18)(31)(32)(33)(34). However, by establishing an in vitro model system of arenavirus RNA synthesis (Fig.…”

Assembly of Arenavirus Envelope Glycoprotein GPC in Detergent-Soluble Membrane Microdomains

“…Expression of the matrix protein Z is sufficient for the assembly and budding of virus-like particles (51,65), and coexpression with GPC and other viral components in reverse-genetic systems gives rise to virions capable of GPC-mediated entry into target cells (36; S. S. Agnihothram and J. H. Nunberg, unpublished data). Recent evidence suggests that the Z and GPC proteins interact directly in virion assembly (16,48). We therefore wanted to investigate whether the distribution of GPC on the plasma membrane might be affected by coexpression of Z.…”

“…The nucleoprotein (N) and the multidomain RNAdependent RNA polymerase (L) make up the ribonucleoprotein core of the virion and together are sufficient for the replication and transcription of the RNA genome (30,35,40). The small matrix protein (Z) is myristoylated and associates with the inner leaflet of the plasma membrane to drive the formation and budding of virion particles (16,51,65). The virus envelope glycoprotein (GPC) is trafficked to the surfaces of infected cells for incorporation into budding virions and mediates the entry of the virus into its host cell.…”

“…In many instances, protein acylation is critical for association with lipid rafts (39,46), and this may be the case for these arenavirus proteins. The matrix protein Z, for example, fails to associate with the plasma membrane in the absence of myristoylation (16,66). Furthermore, the nonmyristoylated G2A mutant of GPC is trafficked to and accumulates on the cell surface, but there it suffers a major deficiency in membrane fusion activity (58,77).…”

Molecular Attenuation Process in Live Vaccine Generation for Arenaviruses

“…G2 has three domains, the outer (caboxi-terminus) domain located outside the virion, the transmembrane domain and the inner (amino-terminus) domain, located inside the virion. The outer domain interacts with G1, the transmembrane domain interacts with the signal peptide, and the inner domain could interact with Z or the nucleocapsid (Capul et al, 2007;York et al, 2004). G2 changes fall inside the transmembrane domain (GPC 427 , FFI) or at the cytoplasmic tail (GPC 446 , TTS) and could affect such important interactions.…”