COOPERATIVE BINDING TO NUCLEIC-ACIDS BY BARLEY YELLOW MOSAIC BYMOVIRUS COAT PROTEIN AND CHARACTERIZATION OF A NUCLEIC ACID-BINDING DOMAIN

The capacity of several coat protein (CP) mutants of a German isolate of barley yellow mosaic bymovirus (BaYMV) to bind to nucleic acids was studied in vitro. Recombinant CP, produced by overexpression in Esche richia coli, was purified from inclusion bodies and subsequently renat ured. Binding to single-stranded (ss)RNA and ssDNA oligonucleotides wa s found to be cooperative and sequence non-specific. By deletion mutag enesis, several truncated CP derivatives were created and their nuclei c acid-binding capacity was investigated in order to define a protein domain responsible for RNA- and DNA-binding. The nucleic acid-binding domain consists of a core which was located to an internal 23 amino ac id peptide (aa 125-147) and an adjacent domain (aa 148-184) which stim ulates binding.