Nucleic acid-binding properties of the P1 protein of turnip mosaic potyvirus produced in Escherichia coli.

The N-terminal P1 protein of turnip mosaic potyvirus (TuMV) polyprotein was overexpressed in Escherichia coli, purified by metal chelation chromatography under denaturing conditions and renatured. U.v. cross-linking experiments indicated that the recombinant protein interacted with RNA, and gel retardation electrophoresis demonstrated that more than one molecule of P1 bound one molecule of RNA. Formation of the protein-RNA complexes was dependent on the conformational state of P1 and was stable at relatively high concentrations of NaCl. P1 had the ability to bind ssRNA and ssDNA, with similar affinity, but was not able to bind to dsDNA. The TuMV protein had the additional characteristic of binding dsRNA with affinity similar to that observed with single-stranded nucleic acids.