Viroid RNA systemic spread may depend on the interaction of a 71-nucleotide bulged hairpin with the host protein VirP1

The TR is responsible for VirP1 binding to PSTVd. (A) The four overlapping PSTVd RNA subfragments that were tested for VirP1 binding in the three-hybrid system. L170 and L280 are left-hand fragments of approximately 170 and 280 bases, respectively. R190 and R80 are right-hand fragments of 190 and 80 bases, respectively. R80 contains the 71-nt TR of PSTVd. (B) Results of the β-gal assay. The RNA hybrids, MS2-L170, MS2-L280, MS2-R190, and MS2-R80 contain L170, L280, R190, and R80, respectively. They were combined with the protein hybrids AD, AD-VirP1ct, and AD-IRP.