TGMV REPLICATION PROTEIN-AL1 PREFERENTIALLY BINDS TO SINGLE-STRANDED-DNA FROM THE COMMON REGION

The AL1 protein of tomato golden mosaic virus (TGMV) is encoded by the viral DNA and has been shown to be essential for viral DNA replication, We have over-expressed the AL1 open reading frame in E coli and purified the protein from bacterial extracts to near homogeneity. Using various different techniques we have studied the interaction of the ALI protein with DNA. The ALI protein is able to bind to DNA containing the common region of the viral genome, which can be demonstrated by photochemical cross-linking. Binding is 4-fold stronger to single-stranded than to double-stranded DNA. Antibodies against the ALI protein can be used to precipitate the protein DNA complex. The binding to single- and double-stranded DNA is specifically to the common region since a DNA fragment unrelated to TGMV is not shifted in a gel retardation assay.