Tobacco calmodulin-like protein provides secondary defense by binding to and directing degradation of virus RNA silencing suppressors.
RNA silencing (RNAi) induced by virus-derived double-stranded RNA (dsRNA), which is in a sense regarded as a pathogen-associated molecular pattern (PAMP) of viruses, is a general plant defense mechanism. To counteract this defense, plant viruses express RNA silencing suppressors (RSSs), many of which bind to dsRNA and attenuate RNAi. We showed that the tobacco calmodulin-like protein, rgs-CaM, counterattacked viral RSSs by binding to their dsRNA-binding domains and sequestering them from inhibiting RNAi. Autophagy-like protein degradation seemed to operate to degrade RSSs with the sacrifice of rgs-CaM. These RSSs could thus be regarded as secondary viral PAMPs. This study uncovered a unique defense system in which an rgs-CaM-mediated countermeasure against viral RSSs enhanced host antiviral RNAi in tobacco.
Plant Breeding Science, Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan. knakahar@res.agr.hokudai.ac.jp
Kenji S
KS
Nakahara
Chikara
C
Masuta
Syouta
S
Yamada
Hanako
H
Shimura
Yukiko
Y
Kashihara
Tomoko S
TS
Wada
Ayano
A
Meguro
Kazunori
K
Goto
Kazuki
K
Tadamura
Kae
K
Sueda
Toru
T
Sekiguchi
Jun
J
Shao
Noriko
N
Itchoda
Takeshi
T
Matsumura
Manabu
M
Igarashi
Kimihito
K
Ito
Richard W
RW
Carthew
Ichiro
I
Uyeda
D001343:Autophagy; D020868:Gene Silencing; D006868:Hydrolysis; D011485:Protein Binding; D034622:RNA Interference; D012328:RNA Viruses / Q000235:genetics / Q000472:pathogenicity*; D012367:RNA, Viral / Q000235:genetics*; D014026:Nicotiana / Q000378:metabolism*
D012367:RNA, Viral