Sequence of the 3'-terminal region of turnip mosaic virus RNA and the capsid protein gene

1 CRESALA, Institut Armand-Frappier, 531 boulevard des Prairies, Ville de Laval, Québec, Canada H7N 4Z3 2 Plant Research Center, Agriculture Canada, Ottawa, Ontario, Canada K1A OC6 and 3 J. A. de Sève Laboratory of Molecular Neuroendrocrinology, Clinical Research Institute of Montréal, 110 Pine Avenue West, Montréal, Québec, Canada H2W 1R7 A sequence of 1801 nucleotides originating from the 3' end region of turnip mosaic virus (TuMV) RNA was cloned using the polymerase chain reaction and found to contain one long open reading frame (ORF). The amino acid sequence of three different regions of the isolated TuMV capsid protein (including the NH 2 terminus) was determined and these partial sequences were found in the translation product predicted to be encoded by the large ORF. The data suggested that the TuMV capsid protein was a product arising from the maturation of a larger polyprotein, as observed for other potyviruses. Furthermore, the putative cleavage site corresponded to a glutamine-alanine dipeptide, a site commonly used in plant virus polyprotein processing. The capsid protein cistron was composed of 864 nucleotides and corresponded to a region encoding 288 amino acids with a calculated M r of 33186; the adjacent 3' non-coding region was 667 nucleotides long. The deduced amino acid sequence of the TuMV capsid protein is closely related to other potyvirus capsid proteins, with most of the variation being found within the NH 2 -terminal region. Received 25 June 1990; accepted 8 August 1990.