RNA-binding properties of proteins of the beet yellows closterovirus

Recombinant p64, p65, p24, p22, p21 of the beet yellows closterovirus and pcp, hel, mtr, and pol fragments encoded by the replication genes of the virus were purified and tested for RNA binding. North-Western blotting revealed the RNA-binding activity for p64 and hel a 21-kDa fragment of the helicase domain with conserved motifs V and VI. Gel retardation assay confirmed hel binding with a randomized RNA probe in vitro, and a cooperative RNA-hel interaction was assumed on evidence of the binding pattern. The RNA-hel complexes proved to be stable at a high ionic strength.