Inducible expression of the vaccinia virus A17L gene provides a synchronized system to monitor sorting of viral proteins during morphogenesis.
AUTOR(ES)
Rodríguez, D
RESUMO
The vaccinia virus (VV) A17L gene encodes a 21- to 23-kDa virion component that forms a stable complex with the 14-kDa envelope protein (A27L gene). In a previous report, we described the construction of a VV recombinant, VVindA17L, in which the expression of the A17L gene is inducibly regulated by isopropyl-beta-D-thiogalactoside (IPTG). We demonstrated that shutoff of the A17L gene results in a blockade of virion morphogenesis at a very early stage (D. Rodríguez, M. Esteban, and J. R. Rodríguez, J. Virol. 69:4640-4648, 1995). In the present study, we show that virus growth is restored if the inducer is provided not later than 6 h postinfection. Immunofluorescence and immunoelectron microscopy analysis of VVindA17L-infected cells revealed that in the absence of the 21- to 23-kDa protein, the 14-kDa protein is distributed throughout the cytoplasm. After IPTG addition, the 14-kDa protein can be detected around viral factories and immature virions; at later times, it localizes in the external membranes of intracellular mature virions. Immunoelectron microscopy with anti-21- to 23-kDa antibodies showed that soon after induction, the protein accumulates in membranes of the rough endoplasmic reticulum and in the nuclear envelope. With time, the protein localizes in viral crescents and subsequently associates to the membranes of immature and intracellular mature virions. These results are consistent with a model in which the 21- to 23-kDa protein would be synthesized at the endoplasmic reticulum, from where the protein could be translocated to the membranes of the intermediate compartment to generate the precursors of the viral membranes. Also, these results argue that 14-kDa envelope protein becomes posttranslationally associated to viral membranes through its interaction with the 21-kDa protein.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=190833Documentos Relacionados
- Vaccinia virus A17L gene product is essential for an early step in virion morphogenesis.
- Vaccinia virus A17L open reading frame encodes an essential component of nascent viral membranes that is required to initiate morphogenesis.
- Regulation of Vaccinia Virus Morphogenesis: Phosphorylation of the A14L and A17L Membrane Proteins and C-Terminal Truncation of the A17L Protein Are Dependent on the F10L Kinase
- Disulfide Bonds and Membrane Topology of the Vaccinia Virus A17L Envelope Protein
- The vaccinia virus 14-kilodalton fusion protein forms a stable complex with the processed protein encoded by the vaccinia virus A17L gene.