A geminivirus replication protein is a sequence-specific DNA binding protein.
The genome of the geminivirus tomato golden mosaic virus (TGMV) consists of two circular DNA molecules designated as components A and B. The A component encodes the only viral protein, AL1, that is required for viral replication. We showed that AL1 interacts specifically with TGMV A and B DNA by using an immunoprecipitation assay for AL1:DNA complex formation. In this assay, a monoclonal antibody against AL1 precipitated AL1:TGMV DNA complexes, whereas an unrelated antibody failed to precipitate the complexes. Competition assays with homologous and heterologous DNAs established the specificity of AL1:DNA binding. AL1 produced by transgenic tobacco plants and by baculovirus-infected insect cells exhibited similar DNA binding activity. The AL1 binding site maps to 52 bp on the left side of the common region, a 235-bp region that is highly conserved between the two TGMV genome components. The AL1:DNA binding site does not include the putative hairpin structure that is conserved in the common regions or the equivalent 5' intergenic regions of all geminiviruses. These studies demonstrate that a geminivirus replication protein is a sequence-specific DNA binding protein, and the studies have important implications for the role of this protein in virus replication.
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Department of Biochemistry, North Carolina State University, Raleigh 27695-7622.
Luckow
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Hanley-Bowdoin
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D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008969:Molecular Sequence Data; D009029:Mosaic Viruses / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication
D004279:DNA, Viral; D004268:DNA-Binding Proteins; D014764:Viral Proteins