The amino-terminal half of Sendai virus C protein is not responsible for either counteracting the antiviral action of interferons or down-regulating viral RNA synthesis.
The Sendai virus C proteins, C', C, Y1, and Y2, are a nested set of independently initiated carboxy-coterminal proteins translated from a reading frame overlapping the P frame on the P mRNA. The C proteins are extremely versatile and have been shown to counteract the antiviral action of interferons (IFNs), to down-regulate viral RNA synthesis, and to promote virus assembly. Using the stable cell lines expressing the C, Y1, Y2, or truncated C protein, we investigated the region responsible for anti-IFN action and for down-regulating viral RNA synthesis. Truncation from the amino terminus to the middle of the C protein maintained the inhibition of the signal transduction of IFNs, the formation of IFN-stimulated gene factor 3 (ISGF3) complex, the generation of the anti-vesicular stomatitis virus state, and the synthesis of viral RNA, but further truncation resulted in the simultaneous loss of all of these inhibitory activities. A relatively small truncation from the carboxy terminus also abolished all of these inhibitory activities. These data indicated that the activities of the C protein to counteract the antiviral action of IFNs and to down-regulate viral RNA synthesis were not encoded within a region of at least 98 amino acids in its amino-terminal half.
Kato
Atsushi
A
Department of Viral Diseases and Vaccine Control, National Institute of Infectious Diseases, Musashi-Murayama, Tokyo 208-0011, Japan. akato@nih.go.jp
Ohnishi
Yukano
Y
Hishiyama
Michiko
M
Kohase
Masayoshi
M
Saito
Sakura
S
Tashiro
Masato
M
Nagai
Yoshiyuki
Y
D000818:Animals; D000998:Antiviral Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation; D006367:HeLa Cells; D006801:Humans; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha / Q000037:antagonists & inhibitors; D016899:Interferon-beta / Q000037:antagonists & inhibitors; D007372:Interferons / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D012367:RNA, Viral / Q000378:metabolism*; D029082:Sendai virus / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014709:Vero Cells; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D000998:Antiviral Agents; D004268:DNA-Binding Proteins; C494227:IRF9 protein, human; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha; D012367:RNA, Viral; D014157:Transcription Factors; D014764:Viral Proteins; C051221:nonstructural C protein, Sendai virus; D016899:Interferon-beta; D007372:Interferons