Requirement of 3'-terminal guanosine in (-)-stranded RNA for in vitro replication of cucumber mosaic virus satellite RNA by viral RNA-dependent RNA polymerase.
The 3' terminus of the (-) RNA strand in the replicative forms of several (+)-stranded RNA viruses possesses an unpaired guanosine with unknown function. This unpaired guanosine is also found at the 3' terminus of the (-) strand in the double-stranded form of two cucumoviral satellite RNAs. Using a cucumber mosaic virus (CMV) RNA-dependent RNA polymerase capable of replicating the satellite RNA in vitro, the 3'-terminal guanosine of the satellite (-) strand was shown to be an absolute requirement for satellite (+) strand synthesis. If genomic RNA synthesis of CMV and other members of the alphavirus-like superfamily that produce (-) strands terminating in an unpaired 3' guanosine follows a similar strategy, the work reported here would represent the first experimental support for the notion of 3'-terminal guanosine functioning as an essential recognition signal for viral replicases, enabling (+) strand RNA synthesis to be initiated internally from a (-) strand template.
Wu
G
G
Molecular Plant Pathology Laboratory, U.S. Department of Agriculture, Agricultural Research Services, Beltsville, MD 20705.
Kaper
J M
JM
D001483:Base Sequence; D017799:Cucumovirus / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D006151:Guanosine / Q000378:metabolism*; D008969:Molecular Sequence Data; D012313:RNA / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D012315:RNA Caps; D019244:RNA, Satellite; D012367:RNA, Viral / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D013698:Templates, Genetic; D014779:Virus Replication / Q000235:genetics*
D012315:RNA Caps; D019244:RNA, Satellite; D012367:RNA, Viral; D006151:Guanosine; D012313:RNA; D012324:RNA-Dependent RNA Polymerase