Nucleotide sequence of the coat protein coding region of tulip breaking virus

cDNA of tulip breaking virus-tulip (TBV-tulip) RNA was synthesized and cloned inE. coli. One clone that contains a 4.5 kb insert was identified by restriction enzyme analysis, dot immunobinding assay (DIBA), and partial sequencing. Then 1479 nucleotides of the 3-terminus of the clone were sequenced and revealed that the sequence contains one open reading frame (ORF), followed by an untranslated region of 255 nucleotides and a poly(A) tract. The deduced amino acid sequence was found to include the C terminus of the predicted RNA-dependent RNA polymerase and the coat protein. A glutamine-alanine dipeptide was identified as a putative NIa protease cleavage site at the N terminus of the coat protein.The nucleotide sequence data reported in this paper have been submitted to GenBank nucleotide sequence database and have been assigned the accession number X63630.     

Analysis of Putative Interactions Between Potyviral Replication Proteins and Plant Retinoblastoma Proteins

Sequence comparisons suggest that the RNA-dependent RNA polymerase (NIb) of potyviruses and bymoviruses, as well as the viral polymerase of potexviruses may contain a putative retinoblastoma protein (pRb) binding motif. The possibility that the potyviral NIb may function in the nucleus through interactions with plant pRb-related (RBR) proteins, and the modifications of the cell cycle was investigated by a combination of mutagenesis of the NIb and yeast two-hybrid system (YTHS). Mutation of a highly conserved glutamic acid residue in the putative pRb-binding motif of the NIb had no detectable phenotypic effect on replication of Potato virus A (PVA). Furthermore, the NIb proteins from Potato virus V and PVA failed to interact with maize or tobacco RBR proteins in yeast. Although the conservation of the motif for pRb interaction in plant RNA viruses is intriguing, these proteins from plant RNA viruses appear not to interact with plant RBR proteins.