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 of nucleic acids was studied in vitro. Recombinant CP, produced by overexpression in Escherichia coli, was purified from inclusion bodies and subsequently renatured. Binding to single-stranded (ss) RNA and ssDNA oligonucleotides was found to be cooperative and sequence non-specific. By deletion mutagenesis, several truncated CP derivatives were created and their nucleic 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 acid peptide (aa 125-147) and an adjacent domain (aa 148-184) which stimulates binding.