Terminal structure of hypovirulence-associated dsRNAs in the chestnut blight fungus Endothia parasitica

摘要

The 3'- and 5'-terminal sequences of the five large double-stranded RNA species (L-dsRNA; 4.5–6.0 X 106 daltons) of EP713, a hypovirulent strain of Endothia parasitica, were determined by mobility-shift and enzymatic methods. All the L-dsKNAs appeared to have identical terminal sequences. A heteropolymer sequence was found at one 3'-terminus and a poly(A) sequence of variable length at the other. It was possible to label only one 5'-terminus using polynucleotide kinase and [γ-32p]ATP, and this was shown to be a poly(U) sequence of variable length. We propose that the dsRNAs have the following structure, where X represents a blocking group: 5'-A(U)20'NNN....NNNGAGCUCACUAUGUAGAUCACCCAUAAGA-3'3'-(A)35'NNN....NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNX-5'A recombinant plasmid containing dsRNA-related sequences was constructed. Hybridization analysis using the recombinant probe indicated that the sequence homology among the L-dsRNAs extended beyond these terminal regions and was also shared by small dsRNAs (0.3–0.45 × 10-6 daltons).