RICE DWARF PHYTOREOVIRUS SEGMENT S11 ENCODES A NUCLEIC-ACID BINDING-PROTEIN

The function of rice dwarf virus segment 11 and the corresponding segm ents of other phytoreoviruses is not yet determined. The amino acid se quence of Pns11, encoded by segment 11, contains a putative zinc finge r and five flanking basic regions at the C-terminus. The full-length P ns11 protein and three truncated derivatives, which lack the N-terminu s, the zinc-finger, or the C-terminal five basic regions were expresse d in Escherichia coil and their nucleic acid binding properties were s tudied. Pns11 interacts with single-and double-stranded forms of DNA a nd RNA in a sequence-nonspecific manner. The truncated derivative whic h contains both the zinc-finger and the C-terminal basic regions has t he same binding properties as the full-length Pns11. However, removal of either of these domains prevents binding activity. The binding acti vity of Pns11 was drastically reduced when the blots were treated with a high concentration of EDTA. Moreover, Pns11 extracted from infected rice also binds to single-stranded RNA. These data suggest that RDV P ns11 binding activity is structure-dependent and it may play an import ant role in virus replication and/or genome assortment. (C) 1998 Acade mic Press.