Small RNA binding is a common strategy to suppress RNA silencing by several viral suppressors.
RNA silencing is an evolutionarily conserved system that functions as an antiviral mechanism in higher plants and insects. To counteract RNA silencing, viruses express silencing suppressors that interfere with both siRNA- and microRNA-guided silencing pathways. We used comparative in vitro and in vivo approaches to analyse the molecular mechanism of suppression by three well-studied silencing suppressors. We found that silencing suppressors p19, p21 and HC-Pro each inhibit the intermediate step of RNA silencing via binding to siRNAs, although the molecular features required for duplex siRNA binding differ among the three proteins. None of the suppressors affected the activity of preassembled RISC complexes. In contrast, each suppressor uniformly inhibited the siRNA-initiated RISC assembly pathway by preventing RNA silencing initiator complex formation.
Lakatos
Lóránt
L
Agricultural Biotechnology Center, Plant Biology Institute, Gödöllõ, Hungary.
Csorba
Tibor
T
Pantaleo
Vitantonio
V
Chapman
Elisabeth J
EJ
Carrington
James C
JC
Liu
Yu-Ping
YP
Dolja
Valerian V
VV
Calvino
Lourdes Fernández
LF
López-Moya
Juan José
JJ
Burgyán
József
J
D000818:Animals; D017360:Arabidopsis / Q000821:virology; D020029:Base Pairing; D004330:Drosophila / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism; D035683:MicroRNAs / Q000378:metabolism*; D018515:Plant Leaves / Q000821:virology; D010942:Plant Viruses / Q000502:physiology*; D034622:RNA Interference; D020871:RNA Stability; D034741:RNA, Small Interfering / Q000378:metabolism*; D034743:RNA-Induced Silencing Complex / Q000378:metabolism; D014026:Nicotiana / Q000821:virology; D014764:Viral Proteins / Q000378:metabolism
D035683:MicroRNAs; D034741:RNA, Small Interfering; D034743:RNA-Induced Silencing Complex; D014764:Viral Proteins