Similarities and differences between the subgenomic and minus-strand promoters of an RNA plant virus.
Promoter regions required for minus-strand and subgenomic RNA synthesis have been mapped for several plus-strand RNA viruses. In general, the two types of promoters do not share structural features even though they are recognized by the same viral polymerase. The minus-strand promoter of Alfalfa mosaic virus (AMV), a plant virus of the family Bromoviridae, consists of a triloop hairpin (hpE) which is attached to a 3' tRNA-like structure (TLS). In contrast, the AMV subgenomic promoter consists of a single triloop hairpin that bears no sequence homology with hpE. Here we show that hpE, when detached from its TLS, can function as a subgenomic promoter in vitro and can replace the authentic subgenomic promoter in the live virus. Thus, the AMV subgenomic and minus-strand promoters are basically the same, but the minus-strand promoter is linked to a 3' TLS to force the polymerase to initiate at the very 3'end.
Olsthoorn
René C L
RC
Institute of Biology, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands. olsthoor@chem.leidenuniv.nl
Haasnoot
P C Joost
PC
Bol
John F
JF
D017794:Alfalfa mosaic virus / Q000235:genetics*; D001483:Base Sequence; D004279:DNA, Viral / Q000235:genetics; D005822:Genetic Vectors; D016679:Genome, Viral; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D018749:RNA, Plant / Q000737:chemistry / Q000235:genetics; D012343:RNA, Transfer / Q000737:chemistry / Q000235:genetics; D014026:Nicotiana
D004279:DNA, Viral; D018749:RNA, Plant; D012343:RNA, Transfer