Processing of the intracellular form of the west Nile virus capsid protein by the viral NS2B-NS3 protease: an in vitro study.
AUTOR(ES)
Yamshchikov, V F
RESUMO
According to the existing model of flavivirus polyprotein processing, one of the cleavages in the amino-terminal part of the flavivirus polyprotein by host cell signalases results in formation of prM (precursor to one of the structural proteins, M) and the membrane-bound intracellular form of the viral capsid protein (Cint) retaining the prM signal sequence at its carboxy terminus. This hydrophobic anchor is subsequently removed by the viral protease, resulting in formation of the mature viral capsid protein found in virions (Cvir). We have prepared in vitro expression cassettes coding for both forms of the capsid protein, for the prM protein, for the C-prM precursor, and for the viral protease components of West Nile flavivirus and characterized their translation products. Using Cint and Cvir translation products as molecular markers, we have observed processing of the intracellular form of the West Nile capsid protein by the viral protease in vitro both upon cotranslation of the C-prM precursor and the viral protease-encoding cassette and by incubation of C-prM translation products with a detergent-solubilized extract of cells infected with a recombinant vaccinia virus expressing the active viral protease. The cleavage of Cint by the viral protease at the predicted dibasic site was verified by introduction of point mutations into the cleavage site and an adjacent region. These studies provide the first direct demonstration of processing of the intracellular form of the flavivirus capsid protein by the viral protease.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=236980Documentos Relacionados
- Upregulation of signalase processing and induction of prM-E secretion by the flavivirus NS2B-NS3 protease: roles of protease components.
- Formation of the flavivirus envelope: role of the viral NS2B-NS3 protease.
- Mutagenesis of the yellow fever virus NS2B protein: effects on proteolytic processing, NS2B-NS3 complex formation, and viral replication.
- Deletion analysis of dengue virus type 4 nonstructural protein NS2B: identification of a domain required for NS2B-NS3 protease activity.
- Cleavage of the dengue virus polyprotein at the NS3/NS4A and NS4B/NS5 junctions is mediated by viral protease NS2B-NS3, whereas NS4A/NS4B may be processed by a cellular protease.