Lassa Virus Z Protein Is a Matrix Protein Sufficient for the Release of Virus-Like Particles

Abstract

Lassa virus is an enveloped virus with glycoprotein spikes on its surface. It contains an RNA ambisense genome that encodes the glycoprotein precursor GP-C, the nucleoprotein NP, the polymerase L, and the Z protein. Here we demonstrate that the Lassa virus Z protein (i) is abundant in viral particles, (ii) is strongly membrane associated, (iii) is sufficient in the absence of all other viral proteins to release enveloped particles, and (iv) contains two late domains, PTAP and PPXY, necessary for the release of virus-like particles. Our data provide evidence that Z is the Lassa virus matrix protein that is the driving force for virus particle release.Lassa virus belongs to the large family of Arenaviridae, including the closely related Lymphocytic choriomeningitis virus (LCMV) and other important human pathogens like Guanarito virus, Junin virus, and Machupo virus. Lassa virus is the etiologic agent of a hemorrhagic fever endemic in West Africa, where annually up to 100,000 cases of clinically apparent Lassa fever occur. Up to 20% of these patients develop hemorrhagic manifestations with a total mortality of 10 to 15% (28,29). In recent years this disease has been increasingly exported from regions where it is endemic to other parts of the world (36).Lassa virus consists of a helical nucleocapsid containing a bisegmented RNA genome surrounded by a lipid bilayer with integrated glycoprotein spikes. Each single-stranded RNA encodes two viral genes in an ambisense coding strategy separated by an intergenic region. The small RNA encodes the nucleoprotein NP (60 kDa) and the immature glycoprotein precursor pre-GP-C (80 kDa), which is cotranslationally cleaved by signal peptidase into GP-C (75 kDa) and a stable signal peptide of 58 amino acids (aa) (10). GP-C is cleaved posttranslationally by subtilase SKI-1/S1P into the N-terminal subunit GP-1 (40 kDa) and the membrane-bound subunit GP-2 (35 kDa). Both subunits are incorporated in virus particles (24,25). The large RNA segment encodes the RNAdependent RNA polymerase L (ϳ200 kDa) and the Z protein with a length of 99 amino acids and a molecular mass of approximately 11 kDa (33,35).During the last few years, the role of the arenavirus Z protein has been elucidated in respect to virus replication. The Z protein of Lassa virus and LCMV contains a RING motif and was shown to have zinc-binding activity (34). Most of the information so far indicates a regulatory role of Z, as the LCMV Z protein was shown to bind to the promyelotic leukemia protein and to relocate nuclear structures formed by the promyelotic leukemia protein (2, 4). The LCMV Z protein has also been reported to interact with the nuclear fraction of the ribosomal protein P0 and with the eukaryotic translation initiation factor eIF4E (3, 7). Furthermore, the Z protein of Tacaribe virus is implicated in RNA synthesis and genome replication in the early stage of infection (13). In contrast, the Z protein of LCMV was not required for RNA replication and transcription in a LCMV minigenome system. Moreover, the Z pro...

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

“…2D). On the basis of previous approximations of the ratio of arenavirus virion proteins (1 L:160 NP:60 GP:20 Z) (24), and the number of packaged NP molecules (∼1,530 copies of NP) (25), the concentration of Z for an approximately spherical arenavirus virion (50-100 nm radius) (26) is estimated to be ∼80-600 μM (SI Materials and Methods). The intravirion concentration of Z is significantly higher than the calculated IC 50 (Fig.…”

Diseases of the central nervous system caused by lymphocytic choriomeningitis virus and other arenaviruses

“…The GPC and Z proteins are required to generate infectious virus-like particles (Lee et al, 2002). The Z protein is also instrumental in arenavirus budding Strecker et al, 2003;Urata et al, 2006).…”

Involvement of host cellular multivesicular body functions in hepatitis B virus budding

“…MVB functions have been similarly implicated in budding by other enveloped RNA viruses, including other retroviruses (28)(29)(30)(31)(32)(33), rhabdoviruses (34), filoviruses (22,35,36), arenaviruses (37,38), paramyxoviruses (39,40), and probably also orthomyxoviruses (41). Therefore, host MVB machinery may be widely exploited for viral budding.…”