Studies on the conditions required for structural and functional maturation of rabies virus glycoprotein (G) in G cDNA-transfected cells.
When the rabies virus G cDNA was expressed with the help of T7 RNA polymerase provided by a recombinant vaccinia virus (RVV-T7), functional G proteins were produced in terms of their ability to induce low pH-dependent syncytium formation and the formation of conformational epitopes, including the acid-sensitive epitope recognized by mAb #1-30-44. Such an ability and the 1-30-44 epitope formation, however, were not associated with the G gene products when G cDNA was expressed without the help of RVV-T7 using a tetracycline-regulated expression vector (pTet-G), although they were normally transported to the surface of established G protein-producing BHK-21 (G-BHK) cells. But, when the G-BHK cells were treated with 2.5 m M sodium butyrate (NaB) after the removal of tetracycline, we could observe not only a much increased frequency of G protein-producing cells, but also the greatly enhanced maturation of the protein. Another short acylate, sodium propionate (NaP), similarly induced increased G protein synthesis at a concentration of 2.5 m M as NaB; however, such proteins were mostly not endowed with the fusion activity nor the 1-30-44 epitope, while NaP at a higher concentration as 5.0 m M did induce similarly the increased production and enhanced maturation of G protein, including the 1-30-44 epitope formation. From these results, we conclude that functional maturation of G protein to acquire fusogenic activity is correlated with 1-30-44 epitope formation, and 2.5 m M NaB not only stimulates G protein production, but also provides such cellular conditions as are required for the structural and functional maturation of the protein.
Sakai
Mai
M
Department of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan.
Kankanamge
Pushpa J
PJ
Shoji
Jun'ichi
J
Kawata
Sanae
S
Tochikura
Tadafumi S
TS
Kawai
Akihiko
A
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D000956:Antigens, Viral / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002087:Butyrates / Q000494:pharmacology; D002460:Cell Line; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D000939:Epitopes; D006023:Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008561:Membrane Fusion; D011487:Protein Conformation; D011820:Rabies virus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity / Q000502:physiology*; D014162:Transfection; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000956:Antigens, Viral; D002087:Butyrates; D018076:DNA, Complementary; D000939:Epitopes; D006023:Glycoproteins; D014759:Viral Envelope Proteins; C064951:glycoprotein G, Rabies virus