AIP1/Alix is a binding partner of Sendai virus C protein and facilitates virus budding.
The C protein, an accessory protein of Sendai virus (SeV), has anti-interferon capacity and suppresses viral RNA synthesis. In addition, it is thought that the C protein is involved in virus budding because of the low efficiency of release of progeny virions from C-knockout virus-infected cells and because of the requirement of the C protein for efficient release of virus-like particles. Here, we identified AIP1/Alix, a host protein involved in apoptosis and endosomal membrane trafficking, as an interacting partner of the C protein using a yeast two-hybrid system. The amino terminus of AIP1/Alix and the carboxyl terminus of the C protein are important for the interaction in mammalian cells. Mutant C proteins unable to bind AIP1/Alix failed to accelerate the release of virus-like particles from cells. Furthermore, overexpression of AIP1/Alix enhanced SeV budding from infected cells in a C-protein-dependent manner, while the release of nucleocapsid-free empty virions was also enhanced. Finally, AIP1/Alix depletion by small interfering RNA resulted in suppression of SeV budding. The results of this study suggest that AIP1/Alix plays a role in efficient SeV budding and that the SeV C protein facilitates virus budding through interaction with AIP1/Alix.
Department of Virology, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. tsaka@hiroshima-u.ac.jp
Takemasa
T
Sakaguchi
Atsushi
A
Kato
Fumihiro
F
Sugahara
Yukie
Y
Shimazu
Makoto
M
Inoue
Katsuhiro
K
Kiyotani
Yoshiyuki
Y
Nagai
Tetsuya
T
Yoshida
D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000502:physiology; D002135:Calcium-Binding Proteins / Q000502:physiology*; D002352:Carrier Proteins / Q000502:physiology*; D018797:Cell Cycle Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D006801:Humans; D012097:Repressor Proteins / Q000502:physiology; D029082:Sendai virus / Q000502:physiology*; D025262:Vacuolar Proton-Translocating ATPases; D033921:Vesicular Transport Proteins; D014771:Virion / Q000502:physiology
D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C117020:PDCD6IP protein, human; D012097:Repressor Proteins; D033921:Vesicular Transport Proteins; D000251:Adenosine Triphosphatases; D025262:Vacuolar Proton-Translocating ATPases; D000074183:ATPases Associated with Diverse Cellular Activities; C490305:VPS4A protein, human