Analysis of the Pancreatic-Ribonuclease-Digestion Products of Alfalfa-Mosaic-Virus Ribonucleic Acid. Sequence Homologies between the Different RNAs (original) (raw)

1975, European Journal of Biochemistry

Alfalfa mosaic virus (AMV) genome consists of three pieces of RNA (24-S, 20-S and 17-S RNA). For infectivity these three RNAs and the coat protein are required. In the absence of coat protein, infectivity is obtained by adding the 12-S RNA also normally present in the virus. This 12-S RNA represents the message for coat protein. Thus a redundancy of the gene for coat protein exists between 12-S RNA and one of the other RNAs. Sequence analysis of the oligonucleotides resulting from pancreatic ribonuclease digestion of the AMV RNAs indicates that the nucleotide sequence of 12-S RNA occurs in 17-S RNA. Analysis of the pancreatic ribonuclease digestion products of the two larger alfalfa mosaic virus RNAs (20-S and 2 4 4 RNA) shows some oligonucleotides containing seven, eight and nine nucleotides with the same structure present in both RNAs. The possibility of a limited nucleotide sequence homology between these two RNAs is discussed. The comparison of the RNase digestion products of 20-S and 24-S RNA with those of 12-S or 17-S RNA revealed no homologous oligonucleotides, thus the origin of 12-S RNA appears to be 17-S RNA. Alfalfa mosaic virus (AMV) is a multicomponent plant virus with a complex genome mainly constituted by four bacilliform nucleoprotein components. Each component contains an RNA molecule of specific length, the molecular weights of which are 1.3 x lo6 (24S), 1. 0~ lo6 (20 S), 0. 7 0~1 0~ (17 S), and 0.32 x lo6 (12 S), respectively [1]. None of the nucleoprotein components is infectious by itself and its RNA is unable to replicate if inoculated alone [2]. To obtain an infectious mixture, the 24-S, 20-S, and 17-S RNAs plus the coat protein must be inoculated, under these conditions 12-S RNA is also present in the progeny [3]. On the other hand, infectivity is also obtained after inoculation of the mixture of all four RNAs 141. From these results it appears that 12-S RNA acts in the initiation of infection if coat protein is absent from the inoculum. Evidence for the capacity of 12-S RNA to code for coat protein has been reported previously [5], Ahhreviutions. Abbreviations for nucleotides follow CBN recommendations. see Eur. ./. Biochem. 15, 203-208 (1970). AMV, alfalfa mosaic virus. Enzymrs. Pancreatic ribonuclease (EC 3.1.4.22), TI ribonuclease (EC 3.1.4.8); spleen phosphodiesterase (EC 3.1.4.1).