Intracellular membrane proliferation in E. coli induced by foot-and-mouth disease virus 3A gene products.
During picornavirus infection replication of genomic RNA occurs in membrane-associated ribonucleoprotein complexes. These replication complexes contain different nonstructural viral proteins with mostly unknown function. To examine the function of nonstructural picornaviral proteins in more detail, cDNA of foot-and-mouth-disease virus (FMDV) strain O1 Lausanne was cloned into lambda ZAP II, and different parts of the P3-coding sequence were expressed in E. coli by the T7 polymerase system. Expression products constituted (a) fusion proteins composed of N-terminal leader peptide of bacteriophage T7 phi 10 protein fused to FMDV P3-sequences of different lengths, (b) translation products of authentic P3-region genes, and (c) carboxy-terminally truncated 3A proteins. Expression products were characterized by NaDodSO4-polyacrylamide gel electrophoresis, immunoblotting, as well as electron and immunoelectron microscopy. We show here that in the T7 polymerase system a high level of expression of 3A-containing peptides is achieved in E. coli. Remarkably, the expression of 3A-derived proteins induced a dramatic intracellular membrane proliferation in E. coli cells, similar to the vesicle induction observed in FMDV-infected cells. By immunoelectron microscopy, 3A-reactive material was found associated with these membranes. We hypothesize that the FMDV 3A protein is instrumental in eliciting intracellular membrane proliferation in infected cells as a prerequisite for viral RNA replication.
Weber
S
S
Institute of Molecular and Cellular Virology, Federal Research Centre for Virus Diseases of Animals, Friedrich-Loeffler-Institutes, Insel Riems, Germany.
Granzow
H
H
Weiland
F
F
Marquardt
O
O
D005537:Aphthovirus / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004926:Escherichia coli / Q000821:virology*; D007425:Intracellular Membranes / Q000378:metabolism*; D008854:Microscopy, Electron; D012367:RNA, Viral / Q000378:metabolism; D014764:Viral Proteins / Q000096:biosynthesis*
D018076:DNA, Complementary; D012367:RNA, Viral; D014764:Viral Proteins