Nucleotide sequence of bean golden mosaic virus and a model for gene regulation in geminiviruses

Abstract

The genome of bean golden mosaic virus, which comprises 2 circular single-stranded DNA molecules (2646 and 2587 nucleotides long) of mostly unique sequence, was sequenced. Comparison of the sequences of bean golden mosaic virus and of cassava latent virus, which share serological relationship but are very different in host range and geographical origin, shows that each virus has a unique 200-nucleotide sequence (common region) on each 2.6-kilobase molecule of its genome. The common regions of the 2 viruses have no sequence homology except for a short inverted repeat near the 3'' end. Six open reading frames were identified that possess considerable sequence homology between the 2 viruses and, in bean golden mosaic virus, may encode proteins of 15.6, 19.6, 27.7, 29.7, 33.1, and 40.2 kilodaltons. Conserved open reading frames are found in both the viral strand and the complementary strand, are approximately the same size, and are in the same orientation with respect to the common region in both viruses. Temporal regulation in geminiviruses may depend on the polarity of transcription and the common region may represent a replication origin and contain elements that serve to modulate gene expression.